0 00:00:09,350 --> 00:00:24,399 Ivan Agullo: Yeah, Thank you for here. Uh. So good morning, Everybody uh welcome. Um. Today we have a panel on. Uh. We call it a quantum information and uh quantum gravity and quantum information. And And 1 00:00:24,410 --> 00:00:40,359 Ivan Agullo: yeah, So we have three panelists, and we try to cover complimentary aspects of the relation of quantum information and and and quantum gravity, and they are, eh, Eduardo, Martin Martinez uh uh Kristina Giselle and Virginia B. Yankee. 2 00:00:40,760 --> 00:00:57,980 Ivan Agullo: The eduardo will talk about um a gravity induced entanglement, while Christina will talk about gravity, induced the coherence exactly the other way around, and and then um Eugenie will talk about uh 3 00:00:58,010 --> 00:01:12,089 Ivan Agullo: hierarchy of entitlement uh uh in in the quantum gravity, if I am, if I am uh right, so these three topics are complimentary to each other, and we hope they will generate a uh a good deal of discussions 4 00:01:12,110 --> 00:01:18,739 Ivan Agullo: as normal with panels, and they will present for ten twelve minutes each. 5 00:01:18,810 --> 00:01:35,230 Ivan Agullo: Sure questions and gratifications are welcome after each talk. Uh, but please hold a longer questions and discussions for the end of the panel, otherwise the the other speakers will have will not have the time left to to speak. And 6 00:01:35,240 --> 00:01:41,350 Ivan Agullo: uh, with no more more delay. Eduardo. Uh, please! The stage is yours. 7 00:01:41,390 --> 00:01:48,959 Eduardo Martin-Martinez: Uh, thank you. But let me share the uh slides. 8 00:01:50,020 --> 00:01:52,440 Eduardo Martin-Martinez: All right. 9 00:01:53,470 --> 00:01:55,510 Eduardo Martin-Martinez: Uh, there we go, 10 00:01:56,420 --> 00:01:59,150 Eduardo Martin-Martinez: hopefully. You see my slides full screen now. 11 00:01:59,690 --> 00:02:08,770 Eduardo Martin-Martinez: Alright, wonderful. Okay. So uh, first of all, thank you very much for the for the invitation to uh to talk in this uh in this panel 12 00:02:08,780 --> 00:02:20,759 Eduardo Martin-Martinez: and to discuss, i'm looking forward to it. Um! This is uh, i'm gonna talk about uh uh some uh opinions if you want of uh uh, the the student and I uh Dallas, Rick Perch 13 00:02:20,880 --> 00:02:30,549 Eduardo Martin-Martinez: and myself uh a half on uh, we can use entanglement and one what they can tell us. Um! What grab you can use in terms of can tell us 14 00:02:30,600 --> 00:02:32,840 Eduardo Martin-Martinez: about quantum gravity. 15 00:02:33,110 --> 00:02:48,419 Eduardo Martin-Martinez: So first of all, let me say i'm gonna say i'm not gonna say things that are uh generally accepted by yeah consensus. If you want it might be some controversial bits. So i'm looking forward to hearing the opinions and uh to hearing now as well. Um 16 00:02:48,430 --> 00:02:54,520 Eduardo Martin-Martinez: what thoughts I got. They this talk may main use uh some again. I'm really really happy to give you stock here. 17 00:02:54,960 --> 00:03:11,370 Eduardo Martin-Martinez: Okay, for the sake of time. Let's just to summarize. I hope this is entertaining. It's very simplified uh the questions that I want to discuss so kindly gravitational interaction entangled to masses, and if we can, we we we don't see the Us like the next slide. You changes like, Oh, sorry. 18 00:03:12,110 --> 00:03:17,170 Eduardo Martin-Martinez: Yeah, Not now. We yeah. But then, if I share screen, maybe i'll share the whole screen 19 00:03:18,050 --> 00:03:21,940 Eduardo Martin-Martinez: them because I was sharing the window, and apparently that was not enough. 20 00:03:22,840 --> 00:03:24,200 Eduardo Martin-Martinez: All right 21 00:03:25,130 --> 00:03:29,510 Eduardo Martin-Martinez: now. Hopefully you'll still see full screen my slide, and it moves. 22 00:03:29,620 --> 00:03:32,519 Eduardo Martin-Martinez: Yes, perfect right. Thank you so much. 23 00:03:33,000 --> 00:03:52,839 Eduardo Martin-Martinez: Alright, So that took the questions that I want to discuss is a candy, gravitational interaction and tangle masses to gravitational masses say that you have quantum degrees of freedom for the position of the masses? Can the gravitational interaction and tangle them? And if so, what does that mean um about the quantum nature of gravity. Imagine that you can actually do an experiment and see entanglement 24 00:03:52,910 --> 00:03:55,700 Eduardo Martin-Martinez: that is mediated by the gravitational interaction. 25 00:03:56,330 --> 00:04:05,819 Eduardo Martin-Martinez: So let me first present uh uh, the idea Uh: this is uh, i'm gonna base the discussion on on an experiment proposal called the Vmp. Experiment 26 00:04:05,940 --> 00:04:09,329 Eduardo Martin-Martinez: uh the Vm: The experiment basically considers two masses 27 00:04:09,380 --> 00:04:18,719 Eduardo Martin-Martinez: right? Uh, and these two masses have some position, quantum degree of freedom, and we can we assume we can prepare them in a superposition of two different paths. 28 00:04:18,779 --> 00:04:38,299 Eduardo Martin-Martinez: Now, uh, there's a person of two different paths that we have here this day that is preferred is uh interacting the two months of interacting through the gravitational introduction. And you can prove one can prove that under those assumptions the state of the masses that originally starting in a separable state end up in an entire state. Okay, 29 00:04:38,980 --> 00:04:53,449 Eduardo Martin-Martinez: so uh discussions can be found everywhere. I just right here the first paper that discusses it, and they consider a Newtonian potential, in which, of course, the the distance between the master's degree of freedom is made out of two quantum degrees of freedom 30 00:04:53,460 --> 00:04:59,499 Eduardo Martin-Martinez: to position the degrees of freedom. And uh, of course it's a quantum potential within the two masses 31 00:05:00,210 --> 00:05:02,519 Eduardo Martin-Martinez: Now, uh, of course, 32 00:05:02,550 --> 00:05:17,810 Eduardo Martin-Martinez: and you start in a separate state, as I said, and uh, after some time you end up in an entangle state. And what are the conclusions that can be extracted? So let me. Just follow um. The reasoning in this paper and several other papers uh talking about similar things 33 00:05:18,150 --> 00:05:20,980 Eduardo Martin-Martinez: Uh, the argument could go as follows: Well, 34 00:05:21,080 --> 00:05:24,780 so local operations and classical communication 35 00:05:24,840 --> 00:05:28,070 Eduardo Martin-Martinez: can not increase the entanglement between two quantum systems. 36 00:05:28,560 --> 00:05:42,500 Eduardo Martin-Martinez: Uh does give. The masses interact only gravitationally, and they get dangled in the gravitational field which is mediating the interaction. It's certainly not doing uh classical communication. So here we have some sort of quantum channel established right 37 00:05:42,520 --> 00:06:01,059 Eduardo Martin-Martinez: now. Hence the field cannot be classical, because it established a quantum channel. Everything uh uh. So this is. This is a true statement Uh, the field seems to be establishing a quantum channel, therefore, uh they feel cannot be classical, and therefore see in ex uh entanglement and experiment like this 38 00:06:01,070 --> 00:06:04,629 Eduardo Martin-Martinez: would be some degree of witness of quantum behavior of gravity 39 00:06:05,930 --> 00:06:18,840 Eduardo Martin-Martinez: now. Uh. So there's reason in that. If a third system, you know, if something is mediating an interaction between two quantum systems and establishing a quantum channel. 40 00:06:18,850 --> 00:06:34,139 Eduardo Martin-Martinez: Uh, does that mean that? Uh, there are uh local degrees of freedom? Uh that in the intermediary system that are quantum? Well uh the the Here's a couple of references where there's a theorem is proved it, which is, uh, actually easy to follow, 41 00:06:34,150 --> 00:06:45,149 Eduardo Martin-Martinez: said, Well, if a third system locally mediates interaction between two systems and the two systems can get entangled. The intermediary system has to be quantum. There's no discussion, no controversial. There has a theorem. 42 00:06:45,270 --> 00:06:52,619 Eduardo Martin-Martinez: So This is suggesting, indeed, that there's something quantum, or there are the quantum degrees of freedom um in the gravitational field. 43 00:06:53,390 --> 00:06:54,400 Eduardo Martin-Martinez: No. 44 00:06:54,860 --> 00:07:08,950 Eduardo Martin-Martinez: The question i'm gonna discuss is whether you can consider gravity to be an intermediary system. If your objective is to prove, uh that gravity is quantum with an experiment in which you can actually see entanglement mediated by writing. 45 00:07:09,780 --> 00:07:16,320 Eduardo Martin-Martinez: So uh, typically, when this is looked at, i'm using some I for this uh, often 46 00:07:16,490 --> 00:07:34,249 Eduardo Martin-Martinez: uh, it is said, Well, but You see, if gravity were not an intermediary system that has local degrees of freedom, then the interaction would be no local. And uh, we know that uh physics has to be local, because, you know, for example, you could say, you cannot really have action at a distance. 47 00:07:34,260 --> 00:07:49,109 Eduardo Martin-Martinez: Um, that's a propagates uh faster than some uh scale, for example, speed of light. So this notion of forbidden non locality should be enough to guarantee that gravity has to be an intermediate. It has to be local degrees of freedom, 48 00:07:49,170 --> 00:07:54,750 Eduardo Martin-Martinez: and for sure, then, the experiment would prove that gravity is quantum that has quantum local degrees of freedom. 49 00:07:55,320 --> 00:08:12,910 Eduardo Martin-Martinez: Now, uh, the notion goes like this mass. One couples to the field, then the field carries quantum information right? It's it's established in a constant channel for sure. So The idea is that mass one couples to the field, and then the field carries the quantum information from us, one to must, two um. Otherwise we would have known locality 50 00:08:13,770 --> 00:08:16,300 Eduardo Martin-Martinez: or actual distance in a way. 51 00:08:16,370 --> 00:08:22,490 Eduardo Martin-Martinez: Now, before discussing uh the models that I want to, I want to uh throw attention to. 52 00:08:32,530 --> 00:08:51,290 Eduardo Martin-Martinez: So operation happen at events in space time, and do not affect other events which are constantly disconnected from this is the notion of locality that uh, any theory of relativity would have um Galilean relativity established an ocean or even locality uh special relativity established. Another gr comes in another, 53 00:08:51,820 --> 00:09:09,030 Eduardo Martin-Martinez: and then we have the notion of system locality. The notion of system locality is something specific to quantum mechanics system. Locality basically says, Well, operations that independently affect the quantum systems must be separable. So you have, for example, a non, a a bipartite unitary operation. 54 00:09:09,040 --> 00:09:17,950 Eduardo Martin-Martinez: That uh uh it, it's describing the action of some local operations on Am me, then this has to be a tensor product between the two. 55 00:09:18,830 --> 00:09:38,759 Eduardo Martin-Martinez: Now, even locality is a fundamental notion in the sense that even locality is something that comes from first principles from postulation, from observation of nature. Where a system locality is an operational notion, it's a way to implement operations that are local. Um that are set to affect only one system. Um, We think quantum mechanics. 56 00:09:38,830 --> 00:09:39,970 Eduardo Martin-Martinez: No 57 00:09:40,170 --> 00:09:48,929 Eduardo Martin-Martinez: uh. The question here is, what notion of locality is the one that is, uh has value of uh first principle. If you want, 58 00:09:49,260 --> 00:09:55,700 Eduardo Martin-Martinez: let me give you a couple of um a couple of descriptions of the Bmv experiment. 59 00:09:55,800 --> 00:10:00,840 Eduardo Martin-Martinez: Uh, that has something interesting about this discussion on this distinction 60 00:10:01,080 --> 00:10:12,539 Eduardo Martin-Martinez: in particular. Let's consider, uh, we grumpy. So this is, uh, I have a classical here, a classical, gravitational field, of course, relativistic description. So here we don't have. This description is going to be even local. 61 00:10:12,680 --> 00:10:19,799 Eduardo Martin-Martinez: Uh. So there's no there's no violations of causality in this description of of gravity, of course, because it's relativistic. 62 00:10:20,440 --> 00:10:36,149 Eduardo Martin-Martinez: And uh, I have here, uh the gravitational field or perturbation of the gravitational field, written in terms of a green function that uh you choose. Now, what is sourcing the feel? And let's say that the feel is source by a small mass we'll know how to do this, 63 00:10:36,160 --> 00:10:46,070 Eduardo Martin-Martinez: the gravitational field perturbation will propagate according to the wave equation associated, or the equation of motion. If you want associated to the degrees of freedom of gravity, 64 00:10:46,080 --> 00:11:04,520 Eduardo Martin-Martinez: and we just insert this treasonary density, and we have the gravitational of generating by a mass. So this is all good. When uh this thing, this t alpha beta is a classical object. Now, when it's a quantum object, Relativity doesn't really tell you anything. Relativity at at most can tell you things about expectation values. 65 00:11:04,690 --> 00:11:06,930 Eduardo Martin-Martinez: Uh in the semi-classical regime. 66 00:11:07,040 --> 00:11:22,270 Eduardo Martin-Martinez: Um, Okay. So let's try to Let's try to describe now to masses in some quantum superposition as in the Vm. The experiment, and let me do a model here. I'm not saying it's a good one. Just the model of doing it. So the model is here. I'm going to prescribe the interaction 67 00:11:22,590 --> 00:11:24,919 Eduardo Martin-Martinez: associated to each state of the particles 68 00:11:24,990 --> 00:11:33,220 Eduardo Martin-Martinez: uh. So that's a the classical field source by each part it. So I have here uh some of two terms in the Hamiltonian, if you want, 69 00:11:33,230 --> 00:11:50,500 Eduardo Martin-Martinez: and each term it's a month right. You have the field generated by one of the paths, as in you have literally a sum of two terms that are the gravitational, the classical gravitational field generated by each of the paths. C. P. One, P. Two are, of course, the choice of part of the masses. So 70 00:11:50,510 --> 00:12:09,039 Eduardo Martin-Martinez: and you can. You can actually compute uh, what is the time? Evolution of the two masses. Right. And of course this is a relativistic description of the both original uh description Right? It's a this is in the in the non-relativistic limit. You recover the Newtonian potential. But the point here is that in this description 71 00:12:09,050 --> 00:12:36,300 Eduardo Martin-Martinez: uh, we have uh it's a description that is even local. This description uh, must be kind of know about Mass a uh before the light crossing time before the the perturbation that must a does, or whatever uh, uh, if you want back the light crossing time. Let's not call perturbation or anything. Now here, that what I've done is a prescription. You see, i'm not saying this is a good description of the experiment, where for each combination of pass 72 00:12:36,310 --> 00:12:45,820 Eduardo Martin-Martinez: I describe that relativistic but classical potential associated with it combination of past, there is no assumption whatsoever about the degrees of freedom of granting 73 00:12:45,940 --> 00:12:57,699 Eduardo Martin-Martinez: this is making no assumptions whatsoever about the existence or not of local degrees of freedom of R. In fact, the phase space of gravity here can be fit to many different theories if you want 74 00:12:58,830 --> 00:13:16,460 Eduardo Martin-Martinez: all right. So, of course, in this case the two masses evolved to an entangle state, as it should right, because we know in the Newtonian limit we had the both results. And in you know, I right in here uh negativity as a measure of entanglement, and one can see that, of course, uh the negativity can be written in terms of the propagators of the green functions. 75 00:13:16,610 --> 00:13:21,199 Eduardo Martin-Martinez: Uh, and indeed, uh, there's some entanglement. After some time this subscription. 76 00:13:21,250 --> 00:13:30,150 Eduardo Martin-Martinez: Now, again, this description made no assumption about the existence or not of quantum degrees of freedom in the gravitational field. All right, 77 00:13:31,450 --> 00:13:35,420 Eduardo Martin-Martinez: now find the coming of the masses through the gravitational interaction 78 00:13:36,040 --> 00:13:44,849 Eduardo Martin-Martinez: can be explained. So I say here does not mean that it has local quantum degrees of freedom can be explained without invoking, without needing the existence of local quantum degrees of freedom. 79 00:13:46,050 --> 00:14:00,880 Eduardo Martin-Martinez: The interaction is certainly not system. Local. Somebody looking at it would say, Well, but the unitary that you're generated is certainly not local. It's not a tensor product. It's not a interacting with the third system, and that's our system interacting with me locally. But it is 80 00:14:08,810 --> 00:14:21,300 Eduardo Martin-Martinez: now an interaction established in a quantum channel does not mean This is one of the messages that I want to transmit. An interaction established in the quantum channel does not mean that it is mediated by a quantum system, 81 00:14:21,310 --> 00:14:37,309 Eduardo Martin-Martinez: it could be a different description. I'm not saying that that different description is uh is uh, what, for example, gravity would reveal is but the point is that you can still write an interaction that is even local. That doesn't defy relativistic assumptions 82 00:14:37,330 --> 00:14:50,119 Eduardo Martin-Martinez: and yet uh can establish a one-on-one channel without assuming that the mediator, field, or whatever the field that is uh uh creating this and this quantum channel that that in this quantum channel has local point, two degrees of freedom. 83 00:14:50,300 --> 00:14:51,310 Eduardo Martin-Martinez: No, 84 00:14:51,590 --> 00:14:57,459 Eduardo Martin-Martinez: we can actually compare with a model in which we do have local quantum degrees of freedom for gravity. 85 00:14:57,510 --> 00:14:59,510 Eduardo Martin-Martinez: Now, uh, 86 00:15:00,070 --> 00:15:16,279 Eduardo Martin-Martinez: oh, this is this is supposed to show. Okay, So what we do is we we consider a a week um a week uh a week gravitational field. To this quantize we can second one. The perturbation is linear gravity, and in your gravity we can write as a quantum field. Fear you no problem. 87 00:15:17,070 --> 00:15:27,340 Eduardo Martin-Martinez: So if we actually do that if we consider, if we consider that uh gravity is quantum, and we have again weak gravity, so it's linear quantum gravity, 88 00:15:27,550 --> 00:15:39,330 Eduardo Martin-Martinez: then we can repeat the same thing. We can actually now couple the quantum degrees of freedom of gravity in our gravity has local quantum degrees of freedom to uh the different. The different degrees of you know the masses 89 00:15:39,370 --> 00:15:44,260 Eduardo Martin-Martinez: by, so that the masses generate the field associated with the path that they're undergoing. 90 00:15:44,450 --> 00:15:46,209 Eduardo Martin-Martinez: If we do that, of course, 91 00:15:46,270 --> 00:15:57,359 Eduardo Martin-Martinez: uh, we obtain this expression. This is the interaction, Hamiltonian. In that case, which is both. Again, there are quantum degrees of freedom in gravity. And uh, there's also the quantum degrees of freedom of the masses. 92 00:15:57,550 --> 00:16:07,779 Eduardo Martin-Martinez: And uh, of course, one would expect, no matter what your quantum gravity one has, one would expect that this limits a week gravity limit uh should be valid in some regime at least. 93 00:16:08,720 --> 00:16:09,840 Eduardo Martin-Martinez: Now, 94 00:16:10,120 --> 00:16:20,409 Eduardo Martin-Martinez: if we are doing the same thing as a summary. But now gravity is locally quantized, and we uh start in the Minkowski vacuum in the far past, and then we let the masses interact. 95 00:16:21,390 --> 00:16:37,149 Eduardo Martin-Martinez: Assume they're not of your position, you get something really similar to the classical case. Not exactly the same. You have some vacuum noise terms. And now, instead of having the the the radiation green functions. You have the five month propagator mediating the interaction. That's a quick sample. 96 00:16:37,830 --> 00:16:44,559 Eduardo Martin-Martinez: Now, uh the results In both cases you end up with entanglement in the massive system. 97 00:16:44,720 --> 00:16:53,490 Eduardo Martin-Martinez: But, uh, I, here is the the modeling which I actually assume that the field has quantum degrees of freedom, and here I have the modeling, which I assume that 98 00:16:53,500 --> 00:17:06,840 Eduardo Martin-Martinez: I so nothing about the decrease of freedom of gravity; and I prescribe that the model is just the superposition in terms of a sum of terms in Hi, so in coherent superposition of the classical gravitational field for each configuration of the masses. 99 00:17:07,210 --> 00:17:15,630 Eduardo Martin-Martinez: In both case this is the one that reproduces the Newtonian case. Both of them are event local. Both of them are compatible with relativistic causality. 100 00:17:15,890 --> 00:17:20,409 Eduardo Martin-Martinez: Uh, but in the first one we have one to local quantum degrees of freedom of. 101 00:17:20,510 --> 00:17:37,610 Eduardo Martin-Martinez: And the question is, is there any difference? So yeah, there are several. These are these two things i'm, not the same. If you actually assume that you have local quantum degrees of freedom. The one thing that you would see that you wouldn't see in the in the case where you have the classical or the quantum control classical case in the case that you associate, the classical 102 00:17:37,620 --> 00:17:43,169 Eduardo Martin-Martinez: relativistic still retarded, feel right. The classical feel associated with it. Math configuration. 103 00:17:43,710 --> 00:17:49,969 Eduardo Martin-Martinez: Uh, in the case of having local quantum degrees of freedom, you can see that entanglement appears between the masses, 104 00:17:49,980 --> 00:18:07,030 Eduardo Martin-Martinez: even while they are space like separated. It's not surprising. This is related to the phenomenon of internal harvesting. The two masses can get entangled by uh harvesting entanglement that already exist in the vacuum state of the gravitational field that is well known in in in in Qft. So it's A. No resulting q Oft. 105 00:18:07,040 --> 00:18:26,769 Eduardo Martin-Martinez: That, of course uh space, like separated radials of space time, contain a contain in quantum fields in space, like if you have regions of space and the degrees of freedom of quantum fields in the two regions that are space like separated, have entanglement, and that Anton can be gathered by systems of massive well system. One, two systems that are interacting with the field. 106 00:18:27,220 --> 00:18:28,680 Eduardo Martin-Martinez: So to end 107 00:18:28,840 --> 00:18:37,999 Eduardo Martin-Martinez: Um, when when we have space like separation In the case of linear quantum gravity, when we model gravity as an intermediary system. We look at one from the degrees of freedom 108 00:18:38,240 --> 00:18:58,109 Eduardo Martin-Martinez: we have entanglement harvesting from the gravitational thing. So if you want it to identify local quantum degrees of freedom of serving entanglement, while they must have paid by separated. Uh, then, if you actually do the experiment and the masses remain space like separated, and they get entangled for sure. This is a smoking gun of the existence of local quantum degrees of freedom for gravity. 109 00:18:58,720 --> 00:19:07,650 Eduardo Martin-Martinez: Now the covering proposals of this experiments work with regimes where the masses are well within coastal contact. What does that mean? Well, that means 110 00:19:07,660 --> 00:19:24,309 Eduardo Martin-Martinez: that means that in principle, if you do an experiment cut with the current proposal of Redeems right. The two masses are in coastal contact, and in principle you could explain the results of serving and tamil, and just of serving entanglement, but without appealing to the existence of local one to the degrees of freedom. 111 00:19:24,320 --> 00:19:44,139 Eduardo Martin-Martinez: Now this is not saying, this is not saying uh that there's nothing interesting about the V. And the experiment in terms of proving that gravity has something quantum about it. So let's see, Let me analyze uh here, uh how we see this, how we see what can be proved with the Bmb experiment when the two guys are still in coastal contact. So the experiment, 112 00:19:44,200 --> 00:20:00,189 Eduardo Martin-Martinez: when as prescribed, definitely proves that semi-classical gravity fails to describe the experiment. Obviously, I mean, we already kind of we already knew that. Uh, that there's no consistent way of coupling a classic on a quantum system, so that was expected. But yes, that would be experimental proof of it, 113 00:20:00,210 --> 00:20:08,030 Eduardo Martin-Martinez: and more than that, the experiment would prove that gravity can set up a quantum channel between the masses That is unc controversial. 114 00:20:08,340 --> 00:20:13,330 Eduardo Martin-Martinez: These two things will be proven if somebody does the Vm. The experiment and files entanglement in the masses. 115 00:20:13,750 --> 00:20:16,970 Eduardo Martin-Martinez: Now, what does the experiment not prove? In our opinion? 116 00:20:16,990 --> 00:20:35,759 Eduardo Martin-Martinez: Well, the experiment does not prove that gravity has quantum degrees of freedom. I can make up a model, as I did what I make no assumptions that the that gravity has quantum degrees of local quantum degrees of freedom, and also that is still even local. So it's there's no violations of causality with that modeling that you have. So in principle, 117 00:20:35,770 --> 00:20:48,040 Eduardo Martin-Martinez: I would say that gravity, having one in the of freedom cannot be proven just by finding entanglement at the end of a Vm. Experiment. Also, it does not prove that there is a quantum superposition of gravitational fields. 118 00:20:48,050 --> 00:20:57,349 Eduardo Martin-Martinez: This is often used, I think. Probably I've used in a bit language, right or quantum superposition of space, and certainly not because in the I know that this claim is controversial. 119 00:20:57,410 --> 00:21:20,649 Eduardo Martin-Martinez: But the reason why i'm making it is because, Yeah, there's no Hilbert space for the in the assumption. Imagine the model that I describe right which I associate, the classical retarded feel uh associated with the two masses uh uh, and then a sum of terms in the Hamiltonian, associated with every classical case, multiplied by the projector associated with the masses being in the particular configuration of paths that I have. 120 00:21:20,660 --> 00:21:39,400 Eduardo Martin-Martinez: That explains the experiment reproduces the Newtonian model in the normal relativistic limit is still a then local. But there's no assumption whatsoever about the face space of gravity. And certainly there's no healer space associated with the field. So even though I know that there is a controversial claim, and i'm looking forward to hearing uh other opinions about this. 121 00:21:39,500 --> 00:21:47,969 Eduardo Martin-Martinez: Um, I would say that certainly can approve that there are, uh there is a quant superposition of gravitational fields, or anything along those lines 122 00:21:48,150 --> 00:22:03,200 Eduardo Martin-Martinez: Now, finally, and I promise it's the last light uh the messages that uh I was wanting to to transmit is that the detection of entanglement to be in the experiment is agnostic to the existence of quantum degrees of freedom in gravity in the gravitational field, 123 00:22:03,210 --> 00:22:12,210 Eduardo Martin-Martinez: unless, of course, one assumes a connection between event, locality and system locality, saying that Well, if I also, if I also assume that the gravitational interaction 124 00:22:12,290 --> 00:22:39,800 Eduardo Martin-Martinez: uh with the masses has to be also system local, just a quantum mechanical assumptions, then, for sure, I agree that it implies that there are quantum local degrees of freedom. But that's an extra assumption. That is something that is made as an assumption. The experiment alone will not be able to prove it. One needs to make that assumption. And my point is that this assumption don't by first principle, there's no good reason to make it from the start, because this is the same as assuming that you, working in a framework like quantum field theory from the start where these two notions are linked, 125 00:22:39,810 --> 00:22:55,379 Eduardo Martin-Martinez: the notion of event, locality and system. Look at the are linked only within the framework of quantum theory, and if you assume that from the start you're already assuming before proving anything that gravity has local quantum, the l of freedom. And I would also argue that the experiment proves many things. But if you also 126 00:22:55,480 --> 00:23:07,909 Eduardo Martin-Martinez: can find in time between the masses while they they remain space like separated throughout the performance of the experiment, and for sure uh that is a smoking gun of the existence of local quantum degrees of freedom of gravity. 127 00:23:08,950 --> 00:23:14,489 Eduardo Martin-Martinez: Uh, that's it. Thank you very much. I hope that didn't take too much too long. Uh, thank you. Sorry. 128 00:23:18,110 --> 00:23:29,059 Ivan Agullo: Thank you, Eduardo. So we are a bit behind on time. Uh, if anybody has a very short clarification needed to go ahead. But but if you not this measured if we keep moving. 129 00:23:32,610 --> 00:23:34,390 Ivan Agullo: So, Gracie. Now please go ahead. 130 00:24:01,770 --> 00:24:06,330 Kristina Giesel: Sorry. I couldn't unmute while I was screen sharing. I'm trying again. 131 00:24:31,980 --> 00:24:51,260 Kristina Giesel: Okay, Can you see my screen. Firstly, Yes, okay. Thank you very much. Yeah. I also would like uh to thank everybody, and and especially with the committee for inviting me for this panel as if I already announced, I will speak about gravitational and use uh decoherence models 132 00:24:51,270 --> 00:25:01,800 Kristina Giesel: and um! I would like to briefly introduce a model that I was recently working on with, uh two of my Phds Rooms with a Cooper and Max Far 133 00:25:02,070 --> 00:25:16,920 Kristina Giesel: and the Long-term aim in this framework would in a sense be to to work towards the direction of Aqg. Inspired gravitational, and use the coherence models. And as a first step we considered a model one. 134 00:25:24,120 --> 00:25:49,350 Kristina Giesel: So we formulate this model in the terms of open quantum systems. So just to remind you, Ah! For an isolated quantum system, we can consider a system, Hamiltonian here denoted by Hs. And we can write down the evolution of the corresponding density matrix of the system by considering just the evolution generated by the system, Hamiltonian on some system of space, one hundred 135 00:25:49,380 --> 00:26:01,749 Kristina Giesel: erez agmoni and an open quantum systems, we ah assume that our total system can be splitted into a system, part which I call as, and some parts which we associate to the environment one hundred and fifty, 136 00:26:01,760 --> 00:26:11,230 Kristina Giesel: and which I call upside on here. And then the dynamics is enlarged in the sense that the total Hamiltonian includes the system part in the environmental parts one hundred and fifty 137 00:26:11,240 --> 00:26:35,959 Kristina Giesel: and an interaction among the two which I denoted by H in tier, and we assume that these interaction can be written as um in terms of product here of system operators, which I call as an environmental operators which I call capital, E. And I five is just some index set here which is running uh, yeah, through some index set, which is characteristic for a given open quantum model. 138 00:26:36,310 --> 00:26:43,670 Kristina Giesel: Now, if we consider this total system, we can also consider its total dynamics here written on the right button 139 00:26:43,680 --> 00:26:57,490 Kristina Giesel: and um. But it turns out often that the total dynamics is very complicated, and what one would like to achieve in such a model is that one can describe an effective dynamics of the system, degrees of freedom, one hundred and fifty 140 00:26:57,520 --> 00:27:10,580 Kristina Giesel: uh, which still encode some effective influence of the environment, and this can be described in the context of so-called master equations which consider the total dynamics shown here below the 141 00:27:10,590 --> 00:27:19,690 Kristina Giesel: and then partially trace out the environmental degrees of freedom. So that we end up with an evolution equation for the system density matrix. 142 00:27:19,960 --> 00:27:49,169 Kristina Giesel: And that's the framework in which we looked at gravitational-induced. Ah, the coherence models. And a famous situation in this context is the lindblad equation shown here on the top, which includes in the first part here unitary evolution generated by a given system. Hamiltonian. This can be corrected by some something which is usually called a lamb shift correction which comes from the interaction with the environment, and modifies, and then sends the unitary evolution. 143 00:27:49,490 --> 00:27:58,850 Kristina Giesel: And then there is a second part, including so-called lindblad operators, which I call a k here, which includes 144 00:27:59,400 --> 00:28:09,409 Kristina Giesel: in a sense also coefficients writing this part, which are time independent, and the lead blood equation, and which are just some numbers depending on K 145 00:28:09,760 --> 00:28:39,219 Kristina Giesel: erez agmoni. So now for a given open quantum model. Once you have chosen the system dynamics, Then, if you look at the Lyme integration basically uh the characteristic choices you can make for your model are the limited operators Ak: and the coefficient Scammer K. And if we think about gravitational, induced the Koreans, it would basically mean that we can choose something specific here in order to make contact to quantum gravity, one 146 00:28:39,920 --> 00:28:55,160 Kristina Giesel: erez agmoni. So let me just explain a very simple example. If we just take one limp plot operator, and so K. Is equal to one, and we take it to be proportional to the Hamiltonian of the system, and if existing some length, shift corrections two hundred and fifty. 147 00:28:55,170 --> 00:29:25,160 Kristina Giesel: If we plug this into the nimblad iteration, we get this simple form here, and if we go to the energy eigen basis. This can be easily, unaddatively solved, and we see that the row, Mm. Um. Elements here for the density matrix obtain the usual unitary evolution here in the difference of the energies, and then some additional contribution which comes with the uh squared difference of the energies which is some decay, has some decay Behavior: 148 00:29:25,170 --> 00:29:30,180 Kristina Giesel: Yeah, yeah. And this is usually called the phasing in the context of open quantum models. 149 00:29:30,860 --> 00:29:39,249 Kristina Giesel: So now, if we think about gravitation and use the coherence. Some phenomenological models take the Lynn per situation as a starting point. We 150 00:29:54,730 --> 00:30:11,870 Kristina Giesel: erez agmoni. But if you look at the assumptions that you need to take if you would like to derive the lindblad equation from the microscopic perspective. And by this I really mean you start with the total system and trace out the environmental degrees of freedom, and then go back to the nint mode equation one hundred and fifty 151 00:30:11,880 --> 00:30:23,699 Kristina Giesel: erez agmoni. Then there are a couple of assumptions necessary in order to arrive at the limitations. So first is the born approximation which assumes an initial separation of the system and the environment. One hundred and fifty 152 00:30:23,710 --> 00:30:43,039 Kristina Giesel: erez agmoni. And then usually you consider stationary state such that even for larger values of t you can write the total density matrix in this form in the system density matrix, which includes the time dependence, and then the environmental density matrix, which we can still approximately assume to be one hundred and fifty, 153 00:30:43,050 --> 00:30:45,230 Kristina Giesel: the same as the initial time 154 00:30:45,280 --> 00:31:04,840 Kristina Giesel: ere, 155 00:31:04,850 --> 00:31:19,470 Kristina Giesel: and then one step. And the Markov approximation is this short memory assumption which allows me to replace basically the density matrix here, which is involved in the integral by just row tilde of T. Such that, 156 00:31:26,230 --> 00:31:33,570 Kristina Giesel: And if we take the Markov approximation seriously, it also means that our correlation functions, which are 157 00:31:33,580 --> 00:31:50,000 Kristina Giesel: erez agmoni uh are involved in these operators. The iphone Ci for you on the button which enter in a massive creation shown above here. Um, where the first mark of approximation has already been applied, one hundred and fifty 158 00:31:50,010 --> 00:32:01,669 Kristina Giesel: um. You see, they involve these correlation functions which we get from tracing out the environmental degrees of freedom, and then they are smeared with system operators. And if these correlation functions are 159 00:32:01,680 --> 00:32:20,609 Kristina Giesel: erez agmoni peaked uh, we can extend the upper limit of the integral to infinity without changing the values of the Alpha and C Alpha too much. And this second step, in a sense, then, allows us to write down a Mathsite equation where these integrals do no longer depend on t one 160 00:32:20,890 --> 00:32:37,709 Kristina Giesel: and um. This is a step you need to do in order to go back to the Lind blood equation, often depending on the model. There's another approximation to the so-called rotating wave approximation which you apply in one hundred and one 161 00:32:37,720 --> 00:32:52,880 Kristina Giesel: uh for these exponential factors. We'd show up. If you have annihilation and creation operators in your system or environmental operators, and then you assume that only terms that these frequencies are, it will contribute to your final last site, which 162 00:32:53,800 --> 00:33:07,249 Kristina Giesel: erez agmoni. So if we consider all these assumptions, And if we want to somehow understand how A. Qg. Could enter into these kind of models, we thought we have to derive them from the microscopic perspective. One hundred and fifty, 163 00:33:07,260 --> 00:33:15,270 Kristina Giesel: and there's already existing work in this direction, using id and variables by an asteroids who blancouver Oliga, and one 164 00:33:15,450 --> 00:33:30,360 Kristina Giesel: Erez agmoni, and uh they coupled to the scale of you to linearize gravity. They also generalize this to photons, and we in a sense slightly modified the model that we started. Uh, not in the atm formulation, but in terms of ourstic are variables one 165 00:33:50,850 --> 00:34:08,759 Kristina Giesel: erez agmoni. And then in this sense we chose a classical dynamic, a reference frame, and afterwards quantized the reduced system, and then we had two D rock observables in the gym in the metal sector denoted by Phi and Pi. Here and then the usual four face-based degrees of freedom in the gravitational sector, one hundred and fifty 166 00:34:09,000 --> 00:34:31,499 Kristina Giesel: uh a positive thing about decoherence, models, and field theory is that you do not really have to put the interaction Hamiltonian by hand. But this is really given um to you by the action to start with, so We also use the usual interaction here between the energy momentum tensor of the Meta field on Minkowski time, coupled to the Pituz 167 00:34:31,510 --> 00:34:32,790 Kristina Giesel: uh Metric 168 00:34:32,870 --> 00:34:34,470 degrees of freedom, 169 00:34:43,670 --> 00:35:01,850 Kristina Giesel: Ah! The free part of the scalar field with unrelation operators a and a dagger. Then we have the um part of the gravitational degrees of freedom where we denote the emulation and creation operators by B and B. Dagger. Ah, by B and Ah, yeah, B and dagger and plus minus for the polarizations. 170 00:35:10,130 --> 00:35:23,759 Kristina Giesel: And then uh these J operators, which include the um emulation and creation operators of the scalar fields uh up to second order, and this comes then from the quantization of the corresponding energy momentum tensor one. 171 00:35:33,250 --> 00:35:37,249 Kristina Giesel: So this is our total Hamiltonian for the decoy ones model, 172 00:35:37,370 --> 00:35:52,480 Kristina Giesel: and then, um! We considered um to start the derivation of our massive creation, the so-called time contribution less um equation, which one can derive from the large once the equation which has 173 00:35:52,490 --> 00:36:00,310 Kristina Giesel: so far no approximations, and this time convolutional situation has the effect that we have a time local bus. 174 00:36:00,530 --> 00:36:08,099 Kristina Giesel: Uh, you can derive this master location order by order. As a first step we basically truncated at second order. 175 00:36:08,410 --> 00:36:19,699 Kristina Giesel: And then in all these models, what you also have to choose is a state for the environment. And here we chose a thermal state for the gravitational environment. 176 00:36:20,170 --> 00:36:50,099 Kristina Giesel: Then we basically uh, could derive from our situation, which tells us the effective evolution of the system density matrix shown here, and on the right hand side we have contribution from the system. Hamiltonian, then from including the self interaction part of the scale of field. We also have a lamb shift contribution that I was mentioning before, and then we have a dissipator which I called Kernel D first here, which is labeled for, 177 00:36:50,110 --> 00:37:07,129 Kristina Giesel: because it can be written in the first um standard Lynn platform nearly uh because, as you can see here below where the first is display it, it has operators. J. A. Jr. Dagger 178 00:37:07,140 --> 00:37:25,059 Kristina Giesel: erez agmoni, which are ordered in a sense similar to what we have seen in the lymphatic equation. But there's a big difference. And then we, these coefficients are A. B. Here are basically still time dependent. So it's no a lot of lint lad type, because we still have this time dependence here one hundred and fifty 179 00:37:29,220 --> 00:37:53,239 Kristina Giesel: erez agmoni A. B sums over from from one up to four, and these different jails we just um divided into different currents here, including different powers of, or different combinations of a and a dig of the scalar field, and the estimation here is over the polarization labels which are still included from the projection. One: 180 00:37:53,250 --> 00:38:01,609 Kristina Giesel: Um, yeah, from the projection operator which acts on these gravitational degrees of freedom which are still evoked in this final equation here. 181 00:38:02,810 --> 00:38:15,789 Kristina Giesel: So uh, we have this final mass situation, and we can, in a sense, partially also confirm the results that were there in the uh literature in the id and formulation. But uh, even 182 00:38:15,950 --> 00:38:33,780 Kristina Giesel: erez agmoni, when I have written down the situation in a quite compact form, it's very complicated. It can't be solved analytically and even numerically, it's hard to solve. So a strategy that was also followed in form. Our work is to project these full mass sake patients with the one part of the case, one hundred and fifty 183 00:38:34,060 --> 00:38:51,650 Kristina Giesel: erez agmoni. And it turns out for these few theory models. You're already in a situation where you have contributions to both divergent integrals. So already, in the simplest case, renormalization is necessary, and people have done this in the adm orders. One hundred and one 184 00:38:51,660 --> 00:39:10,259 Kristina Giesel: erez agmoni. But then, if you look at the one particle case, you have a better control, on which kind of terms will be neglected, or will be cancelled if you apply one of the further transformation approximations like, for instance, the second Markov approximation that you send one hundred and fifty 185 00:39:10,270 --> 00:39:28,759 Kristina Giesel: Erez agmoni, the upper limit of the temporal integral to infinity or the rotating wave approximation. So this is currently work in progress that we try to apply the renormalization before applying further approximations, and then still have, in a sense, the full one particular case, one hundred and fifty 186 00:39:36,690 --> 00:39:57,510 Kristina Giesel: erez agmoni. So, in order to to tell you a very um limiting case of this model um anasstopoulos, and who and also um. Then Vancouver considered that that's the reason why I call it the ahb model. They considered also the one particle case. We normalized went to the non-relativistic limit and considered one hundred and fifty 187 00:39:57,520 --> 00:40:09,459 Kristina Giesel: erez agmoni um only one-dimensional models, and then they ended up with these kind of situation which we have seen at the beginning of my talk, which was the defacing situation. One hundred and fifty 188 00:40:09,480 --> 00:40:34,959 Kristina Giesel: erez agmoni. And coming from this forward gravitational model, they could basically determine the gamma which I had just to choose by starting at the lymphatic equation which includes constants here. So the gravitational pi, the voicemail constant, and one free parameter, in a sense which is related to the temperature of the formal state that we were choosing for the gravitational environment one hundred and fifty. 189 00:40:35,080 --> 00:40:45,040 Kristina Giesel: And uh, we are currently um working on showing that we get the same non-relativistic limit also in that the model we are considering 190 00:40:45,170 --> 00:41:02,240 Kristina Giesel: erez agmoni. So let me uh conclude: why is it interesting in uh quantum gravity, to work with these gravitation and through the coordinates models. In a broader context. It allows, in a sense, a different perspective to chrome and gravity effects coming from the open quantum perspective three. 191 00:41:02,250 --> 00:41:07,939 Kristina Giesel: It is interesting in the context of matter interactions where we often assume gravity is weak 192 00:41:08,110 --> 00:41:28,490 Kristina Giesel: erez agmoni. And uh, because if we consider look fun and gravity, and spy out models in this framework, then. Um! It's interesting to generalize the existing models in the sense that we apply not that for cost, rooting our quantization. But the good quantization and the first steps in this direction in a two 193 00:41:40,750 --> 00:41:59,760 Kristina Giesel: Erez agmoni and Uh. The aim of this kind of program would be to find a Qg. Inspired models which have some characteristic properties which point back or give us the fingerprint of new quantum gravity in the the way how the coherence is manifesting in these models one hundred and fifty. 194 00:41:59,770 --> 00:42:01,129 Kristina Giesel: Thank you very much. 195 00:42:06,160 --> 00:42:10,290 Ivan Agullo: Thank you. 196 00:42:11,810 --> 00:42:21,060 Ivan Agullo: So there there will be time for questions after right to for this. Yes, there will be time for going to after now. It's just a sure a your question, and it's totally pretty short. Go ahead. 197 00:42:23,630 --> 00:42:41,500 Suddhasattwa Brahma: I I have a very good question which is before you. Make this assumptions non-relativistic, and so on you have the tcl to Naka. You must run sick type equation. So from there could you calculate the memory kernel to see how good of an approximation, a link that that approximation would be to that? I mean we is it very pipe sharp with the term 198 00:42:41,900 --> 00:42:54,689 Kristina Giesel: Erez agmoni? Yeah. So um, we can calculate it. And um, the The problem is usually that in order to judge this, you also apply the second Markov equation and send these upper limit to Infinity one. 199 00:42:54,970 --> 00:43:02,560 Kristina Giesel: And then you can basically because we have emulation and creation operators. The time dependence is mainly via exponentials. 200 00:43:02,660 --> 00:43:18,920 Kristina Giesel: Ah, and then you can use further Um: Yeah. Techniques in order to deal with these integrals, and we would like to avoid the second mark of um approximation, and therefore um, it's a bit more complicated than in the standard case. And that's the problem. We are still working on one hundred. 201 00:43:19,520 --> 00:43:20,589 Suddhasattwa Brahma: Thank you. 202 00:43:21,610 --> 00:43:25,880 Ivan Agullo: Very good. And um! You are the next 203 00:43:40,900 --> 00:43:43,680 Eduardo Martin-Martinez: You're You're muted, Virginia right? 204 00:43:44,070 --> 00:43:47,140 Eugenio Bianchi: Thank you. Can you see my screen, is it? Everything is working 205 00:44:26,720 --> 00:44:49,740 Eugenio Bianchi: uh? So i'm trying to go as close as one can get within the quantum gravity to what one call some many body conference system or a condens matter system, and try to highlight without the differences, but also try to bring in as many as the methods as one can in in this specific case. So the model system that I would like to discuss is, 206 00:44:49,750 --> 00:45:03,759 Eugenio Bianchi: uh, take the kinematic a little bit space or quantum gravity. Fix the graph, even assume that it's cubic cubic lattice and finite set of notes, for instance, uh, with some identification towards like identification, 207 00:45:03,830 --> 00:45:15,230 Eugenio Bianchi: and fix also the speeds or the spins to be equal to P. Equal to J. Not so what is left as the degrees of freedom are just in terms of these six valid notes. 208 00:45:27,860 --> 00:45:41,239 Eugenio Bianchi: The dimension of the full system is finite, and, uh, a generic state in the system is a superposition of a Uh Uh product. States of interference at it. Not 209 00:45:41,250 --> 00:46:07,150 Eugenio Bianchi: okay. So one as a tensor product structure, and one can start the standard. The uh discussion of states for this many body systems as it's done in connect matter. There's a separate question, or how to generalize all of these aspects to full quantum gravity or so to a larger portion of the kinematical space that I'm not going to address. Yeah, I want to focus on this very specific model. 210 00:46:13,890 --> 00:46:39,729 Eugenio Bianchi: And what I want to I like is that within the space within this huge space uh it's potentially large in dimension. Uh, we've got the number of uh notes or sites one can organize States in a way that is different from how we generally do for our Northern Ireland system. In our ordinary quantum system you organize states by the energy we speak about low energy States ground state. 211 00:47:02,360 --> 00:47:22,899 Eugenio Bianchi: Yeah, in quantum gravity. Uh, uh, we we don't have any immediate notion of energy that we can use, and so it's often useful to reverse the logic. Reversing the logic means, uh uh identifying properties that characterize the States and using them uh to organize, deliver space 212 00:47:53,910 --> 00:48:09,969 Eugenio Bianchi: volume, low states which are the states that we are genetically. If you pick a state of and area low states, let me uh uh uh zoom in this picture because, uh, uh, that they should clarify one of the aspects. 213 00:48:09,980 --> 00:48:33,169 Eugenio Bianchi: Uh: So yeah, i'm plotting the entropy as a function, subsystem sites, zero, subsystem zero entropy, full system, zero entropy. Uh, there's a theoretical maximum for for the entropy and the uh page Classical result is that if you pick a state at random in deliver space. It's very close to have maximum entanglement to before regions 214 00:48:33,180 --> 00:48:35,370 Eugenio Bianchi: which here would mean a volume 215 00:48:35,950 --> 00:48:37,509 Eugenio Bianchi: Now, uh, 216 00:48:53,980 --> 00:49:13,749 Eugenio Bianchi: and it's only when you lower the energy, and you get close to the boundary of the spectrum in particular, close to the ground state that you have a transition from this linear behavior in volume to a fraction of power blow behavior that is an area low, a dependence only on uh, uh, 217 00:49:14,360 --> 00:49:16,460 Eugenio Bianchi: near boundary correlations. 218 00:49:53,700 --> 00:50:10,660 Eugenio Bianchi: Okay, I update that Uh: this scheme helps with what I'm going to discuss in a moment, because all of these structures are present within this model system, and also more broadly in the larger space of look what to morality. But I cannot use energy anymore as a way of characterizing them. 219 00:50:11,020 --> 00:50:23,659 Eugenio Bianchi: Okay. So now i'm going to give examples of States in this classes, and uh, what I see as they roll up uh in the present, my present understanding of the to 220 00:50:59,710 --> 00:51:18,779 Eugenio Bianchi: uh one point, two point three point, and I or the correlation. See I'm. Focusing on two point correlations. So, for instance, you could have a region and observable in this region another region and observable cities of the region, any kind of observables, and you are interested in the correlation function, the connected correlation function 221 00:51:18,790 --> 00:51:20,210 Eugenio Bianchi: in a given state. 222 00:52:29,480 --> 00:52:32,670 Eugenio Bianchi: So let me look for that product states 223 00:52:43,080 --> 00:52:58,540 Eugenio Bianchi: the basis uh, like the recaping basis of interest liners. So it's a product state uh one can do better. One can take coherent states of the kind of query in theft. Winners like the living. 224 00:52:58,820 --> 00:53:00,370 Eugenio Bianchi: Not by no 225 00:53:00,530 --> 00:53:14,489 Eugenio Bianchi: one can even choose uh the shape of this uh semiclassic to be picked on something we've uh matching, for instance, here. Uh, I consider two big clients. I could pick each one of them on a cube 226 00:53:44,270 --> 00:53:46,439 Eugenio Bianchi: uh on the 227 00:54:16,520 --> 00:54:31,739 Eugenio Bianchi: and uh, and there's a notion of a uh uniform measure on the units here, if you want to, or a large measure of a units uh. So i'm giving you that a software, this uniform measure. You could consider all the measures 228 00:54:31,980 --> 00:54:48,070 Eugenio Bianchi: and notions of random. We respect what that measures uh, we have explored a a large class of other measures, and found that it still volume low with a different slow. So i'm going to consider just the simplest case for for illustration Here 229 00:55:13,930 --> 00:55:17,140 Eugenio Bianchi: I would be 230 00:55:17,260 --> 00:55:18,510 Eugenio Bianchi: the score 231 00:55:28,560 --> 00:55:35,469 Eugenio Bianchi: and uh variance or the dispersion. You see that the discussion goes down uh exponentially fast. 232 00:55:35,930 --> 00:55:55,439 Eugenio Bianchi: The uh average is a volume law. We want exponentially small correction. You plug it into this expression, and you'll find a typical value correlation functions so concretely you could consider angling or correlation functions for, uh uh, for cubes 233 00:56:25,270 --> 00:56:44,730 Eugenio Bianchi: are the classical geometry that source, size and a question. But the fluctuations are also correlated as a perturbation of uh, the theoretical perturbation of a background accurate, related in a State. It is low energy, or at least it is a uh uh 234 00:56:44,820 --> 00:56:54,590 Eugenio Bianchi: that you that supports that. Uh, that is well described by quantum fifty. Right? Then, you would that we would need long range correlation. So certainly the States Don't Sound. 235 00:56:55,010 --> 00:56:56,140 Eugenio Bianchi: Okay. 236 00:57:20,120 --> 00:57:29,719 Eugenio Bianchi: And as soon as the degeneracy in states of the next, your states goes down because you are getting too close, very close to the ground state. You have a transition to area law, 237 00:57:29,750 --> 00:57:33,500 Eugenio Bianchi: and you can use this notion of area 238 00:57:33,550 --> 00:57:38,709 Eugenio Bianchi: uh indication that you are a low energy, that you are uh close to the ground. State 239 00:57:57,540 --> 00:57:58,819 Eugenio Bianchi: um 240 00:57:59,610 --> 00:58:17,610 Eugenio Bianchi: The computational basis, the one that you would use for exact diagonalization of your and Mythonia the product basis that is not adapted to to look at low energies. These zero low States they don't exist at all in quantum fifty or it they don't even belong to folk space. 241 00:58:17,620 --> 00:58:35,389 Eugenio Bianchi: And uh, in a Condes matter, as I was emphasizing before they are I energy, and I would have to superpose high energy states in such We've launched this person in energy. Yeah. So I I I that are generally, I should say, to get a low energy state. 242 00:58:35,420 --> 00:58:39,510 Eugenio Bianchi: Yeah. So uh, yeah, 243 00:58:41,190 --> 00:59:05,810 Eugenio Bianchi: on the other ending one to me that you don't have any median notion of energy or energy density. But you can reverse the logic exactly as from those there's like condense matter basics, and you send tangent as a problem. And this is what we propose. Some years ago, together with Rob Myers. So we identifying the corner of the river space uh, or quantum gravity that supports any classical States, as the area low corner. 244 00:59:34,170 --> 00:59:46,080 Eugenio Bianchi: By saying, Take a region, take a larger region and take the usual information between the interior and the stereo, and this one captures an area law from long range correlations. 245 01:00:16,710 --> 01:00:25,570 Eugenio Bianchi: That this is the way, For instance, Uh, Eduardo described it before, like this experiment's great time and is produce. You stop assuming that there's no entanglement, 246 01:00:25,580 --> 01:00:37,920 Eugenio Bianchi: and there is a question uh, there is a fact. First of all, that is, in two hundred and fifty. We start with the assumption that the out of vacuum is entangled in a very specific way 247 01:00:47,830 --> 01:01:00,810 Eugenio Bianchi: allows this. We use them all the time as a basis of states. And so there's a question or a scenario, if you want uh. They thought that I want to put that for discussion. That is, uh 248 01:01:13,920 --> 01:01:30,069 Eugenio Bianchi: to area alone. A primordial face, a plan face different from the ones that we have discussed. Uh, in the recent that have been discussed in the recent literature, where one starts with zero low States, and it's the dynamics that those the analog of a quantum quench 249 01:01:30,150 --> 01:01:44,440 Eugenio Bianchi: uh in uh incompetence matter systems uh what? That would be the origin of all of the space like correlations. Now, if you wish to do this in quantum fifty or that would be no chance of doing that, because this zero low States are I energy 250 01:02:16,610 --> 01:02:39,880 Eugenio Bianchi: are allowed in Gilbert Space at this uh, uh, in this bket face. But then, as special, the real that is become important, the produce correlations and the open question is, is this a realistic scenario, where all the correlations that we see in quantum fifty-eight, and we also see in the sky are produced in this uh uh 251 01:02:39,890 --> 01:02:44,770 Eugenio Bianchi: primordial face. Okay, uh, I'll stop. Yeah, Thank you. 252 01:02:48,080 --> 01:02:57,869 Ivan Agullo: Thank you, eh? Eh? Jen? You very dressing uh any, any short uh question for Virginia before we we move to the to the, to the discussion session. 253 01:03:00,770 --> 01:03:20,339 Ivan Agullo: Okay, So so we had this, this, this three uh very interesting talks uh each of them. Uh, eh? Providing a glance to different aspects of of quantum information and and and gravity. Uh, on the one hand, eh? Eh, Eduardo? Uh, you know to us that you know. 254 01:03:20,380 --> 01:03:39,830 Ivan Agullo: Uh trying to prove experimentally this uh quantum nature of gravity can be more challenging that that that what other people uh believe this is a very controversial topic, and we will discuss more about it, but is what is very interesting. And also he made this point that you know, if we are able to make sure 255 01:03:39,840 --> 01:03:43,509 Ivan Agullo: entanglement mediated by gravity between 256 01:03:43,600 --> 01:03:47,350 Ivan Agullo: particles which are out of council contact that would be 257 01:03:47,400 --> 01:03:50,480 Ivan Agullo: uh smoking and for quantum gravity for sure, 258 01:03:50,530 --> 01:04:04,009 Ivan Agullo: and and that makes connection with the genius stock. Uh, you know, this zero law Uh um uh States. Uh second law States volume law states these transitions uh that could. 259 01:04:17,990 --> 01:04:32,830 Ivan Agullo: So there is a connection there and then uh Christine and uh, provided a different viewpoint. How gravity, you know, can, in fact, uh destroy quantum coherence Uh, of all the ships systems propagating the their own. 260 01:04:32,840 --> 01:04:52,209 Ivan Agullo: So thank you. The three of you for providing this three uh uh different and complementary uh aspects of quantum information and gravity. And now we kind of start with the discussion. Uh, I see that uh Kavlo. Ah has his hand. He was the first one. So so just go ahead. Kablo. 261 01:04:56,040 --> 01:05:14,199 Western: Okay, Um, Can you hear me? I'm talking from the Not from my computer for the Western connection one. So um, uh, Thank you, even I it's the all all three. Um presentation was super interesting, and I've learned a lot from from from all of them. There's so much to to to to take out of all this. 262 01:05:14,210 --> 01:05:44,190 Western: But I want to um uh take Eduardo invitation uh, at the beginning to to the cats welcome disagreements, and and uh, uh, uh sort of uh, uh politely disagree uh with this uh uh conclusion, I I think he he did a very good job in the in uh uh focusing on the this question of what the uh, the the the the the experiment uh shows, and I think 263 01:05:44,200 --> 01:06:12,369 Western: I think that your model is very good, because it's It's exactly what one should the uh focus on that. And so I I think I certainly agree with all your equations and the most of the things you say. It seems to me that what you show is exactly the opposite of what you um uh in words conclude that uh, for two reasons which i'm gonna say briefly, the the important is the second, but the the first one is the one, probably that creates confusion. 264 01:06:12,490 --> 01:06:29,440 Western: Um. So the first one is that it? It seemed to me you're attacking a strong man uh one of your conclusion is, if we don't do any additional assumption. We can't um uh uh derive anything from a positive outcome of the experiment. 265 01:06:29,560 --> 01:06:38,190 Western: Uh, my reaction is, of course, but this is written in all the papers uh about the the experiment, the the regional paper by 266 01:06:38,200 --> 01:06:49,720 Western: um uh, both in and others that make it very clearly. I mean, if you from the experiment itself. Nothing can be concluded. You need some more. Um, You need the existence of a field, et cetera, 267 01:06:49,730 --> 01:07:01,509 Western: and uh, my paper with my use, which are the strongly that this is evidence for a superposition of geometry. Uh makes very clearly that, uh, the experiment itself is evidence of nothing. 268 01:07:01,580 --> 01:07:12,720 Western: In fact, in physics a single experiment is always evidence of nothing, and unless you have a lot of other assumptions, and the two key assumptions here are: first of there is a field. 269 01:07:13,200 --> 01:07:17,680 Western: Unless we assume there is a field it takes, for it is nothing 270 01:07:26,930 --> 01:07:44,239 Western: now they have, and that's might be my eating events in the quantum information community, somebody who hoped to side step these assumptions. I don't know if there was somebody who's size well to size this assumptions I don't understand what they're talking about. 271 01:07:44,250 --> 01:07:50,460 Western: So if your disagreement is with the hope of side stepping these assumptions, i'm a leader right? 272 01:08:01,030 --> 01:08:22,410 Western: And somebody would tell me about this experiment proof the uh the gravity upon ties, and I would say, under which assumptions Well, it's out of this a field in the field. It's, it's, it's it's It's space time, I would say. Of course, give them double price, and we have These are good as option. Okay, Now let me come to it specific, your model, because that's my second point, and what I will focus on 273 01:08:22,420 --> 01:08:40,649 Western: and what is very good. So you say, Um, it's it's sufficient for describing what is going on. You say the way I need it. Suppose there is a thing it should call H: Okay. And I want to go to say what this is, a fluctuation of the job, and I can describe this H. Now you notice 274 01:08:40,890 --> 01:08:51,359 Western: that this field has no degrees of freedom. I I think. What you should notice is that this field has no independent degrees of freedom, and that may come back to this distinction. 275 01:08:51,880 --> 01:09:07,119 Western: Now, if there's a field, there something can be measured right. You can go hard with, stored by something that measure the electric magnetic field. So the question I would ask you is in assuming that this description is is correct, Is this thing possible? 276 01:09:07,760 --> 01:09:14,779 Western: If it is classical, it has a value in any given experimental situation, uniform in every point of space time. 277 01:09:15,279 --> 01:09:31,290 Western: So in the description you're giving is this field. Has this Feel the value in theical in any point of space time? Of course not because you show up your equations, Let's say, to understand what's going on. We're assuming that is, some of two something I 278 01:09:31,300 --> 01:09:45,899 Western: to configurations to find them uh contribution, or find that some to vectors in the space whatever uh which you can actually put us in the space of the particle in the space of the field in the space of the 279 01:09:45,920 --> 01:09:52,910 Western: slave to the particle, whatever you want, but the actual field doesn't have a single value. If it had a single value it, 280 01:09:53,270 --> 01:10:00,680 Western: there would be no interference and no effect. So the field is on classical. That's what we's, meaning by a class not being no classical. 281 01:10:15,600 --> 01:10:29,480 Western: And if we fold in the second assumption, which in this community is sort of but our bread and butter, namely, that this is this gravity, and it determines the position of so it depends what the clocks do and what the the roles do. Then 282 01:10:29,590 --> 01:10:46,490 Western: conclusion is that what determines what the clock do is not doesn't have a single value, namely, there is not a single geometry understand what it goes on with this X assumptions. We need to think of the possibility that the geometry is not doesn't have a single value. 283 01:10:46,630 --> 01:10:52,460 Western: So it seems to me that all your analysis and your field that 284 01:10:52,610 --> 01:11:08,200 Western: uh, we use it. Field show shows that this is a geometry. It cannot be a classical geometry. If um the experiments uh give the result that no one is that. And if these assumptions are formed in 285 01:11:11,800 --> 01:11:24,929 Eduardo Martin-Martinez: Ivan, can I thank you, Carlo. This is is great. Uh, you see the it's difficult, uh, always difficult, to discuss this things, because I agree, let's say, with ninety percent of everything you said as well. 286 01:11:24,940 --> 01:11:42,609 Eduardo Martin-Martinez: Uh. So that makes it. That makes it tough right to find the the the the nuance, I guess, on the on what um what I think is non-trivial here. Um, So I agree with let me first say things that I agree with. I agree that finding entitlement in the Vm. The experiment would be proof 287 01:11:42,620 --> 01:11:54,550 Eduardo Martin-Martinez: uh that the gravitational field cannot have a classical description in the way you said Right? I mean, you definitely cannot have a description of a field that is well defined in every point of space time. For sure, a hundred percent 288 01:11:54,580 --> 01:12:05,479 Eduardo Martin-Martinez: uh. The second thing is that indeed, it proves that gravity, or would prove that gravity is not classical in the sense of being able to associate a classical face space. 289 01:12:05,960 --> 01:12:21,520 Eduardo Martin-Martinez: That uh, I never said that uh that they feel is classical in the model that I consider. I call it. In fact, the the the name we use is onefully controlled classical uh as opposed to classical. But um! But here's the thing, and it's also agree with what you say so in this kind of model 290 01:12:21,610 --> 01:12:32,930 Eduardo Martin-Martinez: there's no local degrees of freedom. So first we that assumption, and we discuss the assumptions right uh without extra assumptions, what we have here is that the model number one? That would explain the experiment? 291 01:12:33,160 --> 01:12:44,690 Eduardo Martin-Martinez: Um has no assumptions about the degrees of freedom of gravity whatsoever, so you can fit any degrees. So if you can actually find a theory that fits in there like, I can complement this with some theory for the field, 292 01:12:44,930 --> 01:12:59,049 Eduardo Martin-Martinez: then uh uh, the point is is quantum. Gravity is that gravity has quantum because of the the only way in which I can complement this agnostic model about what gravity degrees of freedom are are, uh in this particular experiment. 293 01:12:59,270 --> 01:13:13,299 Eduardo Martin-Martinez: And the answer is, No, you cannot. You cannot really definitely. You can consider, uh, the existence of local quantum degrees of freedom for the field, and I agree with you in some regime. Uh, it will be described with this classically control model, 294 01:13:13,310 --> 01:13:30,519 Eduardo Martin-Martinez: but in general you cannot. Uh, I don't see a reason, at least when you can. Now, of course, one is to compliment with extra assumptions. Now my point would be. I guess the controversial points is uh whether the assumptions are uh begging the question or not, and I think that's where we would probably disagree 295 01:13:30,530 --> 01:13:47,680 Eduardo Martin-Martinez: because the main assumption that one needs to do in order to actually associate. Um uh, the existence of local degrees of freedom is this: This is something that I mean, that's um uh quantum. Locality and relativistic locality are the same notion, 296 01:13:47,690 --> 01:14:04,620 Eduardo Martin-Martinez: so you can certainly take that as an assumption, and they agree. If you take that as an assumption, I think there's no way out other than if you find entirely in the Vm. The experiment. Gravity is quantum. Ask one to local degrees of freedom. Now the question is whether you can make that assumption right, and the the point is that in the way I understand it, 297 01:14:04,710 --> 01:14:20,649 Eduardo Martin-Martinez: and that assumption together is only done, and he's done in qft. Making that assumption from the beginning is assuming that you're moving in a framework. The fact that quantum, locality and relativistic locality are connected. We'll not let's not call it relativity. 298 01:14:20,660 --> 01:14:33,690 Eduardo Martin-Martinez: The notion of coastal structure or locality in the sense of coastal structure and locality in the quantum sense are linked The frameworks in which we link the two are very particular, and in particular the framework in which we would link it 299 01:14:33,710 --> 01:14:39,600 Eduardo Martin-Martinez: um in. We gravity would be a qft, So the point would be whether making that assumption 300 01:14:39,660 --> 01:14:58,240 Eduardo Martin-Martinez: it's already assuming from the beginning that there's a qft behind the whole uh description of gravity, right? So whether the experiment can prove it or not, so maybe, if one of the assumptions is that you have these two notions of locality linked. Maybe you're assuming already that gravity can only be described through a uft, and this is, I think, 301 01:14:58,250 --> 01:15:18,219 Eduardo Martin-Martinez: the only point in which I would disagree, because I fully agree that, uh, proving that for uh showing the entanglement, deb and the not space like in time, and if you find space like in time, and that is amazing, because you can say a lot, then you can say a lot about the existence of quantum degrees of freedom of gravity. If you just find entanglement, then you know that there's no one single model that can do it. You can have a lot of models 302 01:15:18,230 --> 01:15:20,929 Eduardo Martin-Martinez: that can actually fit uh this description, 303 01:15:20,940 --> 01:15:47,529 Eduardo Martin-Martinez: because I have a description that makes no assumptions about the degrees of freedom of gravity. Now, whether you can assume you can complete that with extra assumptions, and whether those assumptions are assuming already that you feel has quantum degrees of freedom or not, I guess is my my new ones here, because I fully agree. The experiment proves that gravity established a quantum channel, which means that 304 01:15:47,540 --> 01:16:07,189 Ivan Agullo: certainly experimental proof that semi-classical gravity has no hope Right? It's uh other than that. If you assume that gravity is a field theory like in in gr, that's the experiment tells you that these are quantum field theory. I would say no, because in the first model that I paid, i'm using 305 01:16:07,200 --> 01:16:17,849 Eduardo Martin-Martinez: that what I I don't know, depending on what you mean. Right? So if you keep in mind that in the first model that I presented every path, every term in that Hamiltonian is coming from the classical field theory. So the modern is relativistic. 306 01:16:32,160 --> 01:16:37,390 Eduardo Martin-Martinez: Anything about the the quantum locality of the funeral right? And, as Carlos said it, 307 01:16:37,400 --> 01:16:52,739 Eduardo Martin-Martinez: in that case is quantum. The model is one because of the masses, so it's indirectly quantum. In a way. The quantum decrease of freedom are in matter. I'm. Not in gravity in this case it's an a few. Let's talk about the model you presented. Not that is, is there a field 308 01:17:00,940 --> 01:17:12,360 Eduardo Martin-Martinez: in the sense that it's not defined at one point in space time at at every point in space. Time, in that sense is not a you? Yes, there is a field. Is it a classical. No, it's not classical, 309 01:17:13,340 --> 01:17:30,099 Eduardo Martin-Martinez: but it's also not quantum. That's the point. It's not well. You are assuming that there might be something which is not classical as a quantum. I'm not assuming, but I don't believe that's true. I mean, I I believe that there would be a quantum field, of course, but the point is, if you look at the experiment for the agnostic point of view, 310 01:17:30,160 --> 01:17:31,989 Western: you said, there is a field. 311 01:17:32,450 --> 01:17:35,120 Western: Okay? And it's not classical. Yeah. 312 01:17:35,330 --> 01:17:39,849 Western: But what you're saying is that it might be that there is a field is not classical, 313 01:17:40,460 --> 01:17:51,969 Eduardo Martin-Martinez: but it's something else. We don't know that is neither classic or not. One zoom, for example, it could be the masses, the way masses interact again. This is not something, I think, that 314 01:17:52,440 --> 01:18:02,280 Western: all experiments, the Higgs feel the the the the, the the gravitational wave, detection, everything. 315 01:18:10,430 --> 01:18:21,930 Western: When we say this is fairly prove something. Okay, when we say uh the detection of the invitation waste proof that the line will present proved that 316 01:18:22,400 --> 01:18:38,459 Western: I can always cook up something which says, No, it does not proof. You know, that it is because it might be something which is not a it's not a quantum theory. It's not that it's something we don't know, and yet it could. It could give this phenomenal. 317 01:18:39,080 --> 01:18:48,130 Western: Yes, of course. But what is interesting in saying that the same phenomenon could come from something with knowing what it is, 318 01:18:48,380 --> 01:18:59,979 Western: and it doesn't fit in any of the way we used to describe the the way we used to describe Nature's classical in theory, classical interactions, quantum interaction want to good theory. 319 01:19:00,620 --> 01:19:03,440 Western: The experiment rules out 320 01:19:04,230 --> 01:19:19,119 Western: the possibility that there is a classical field that that describe the uh, the gravitational direction, and that this classical field that um can be interpreted as the Jo into space time that's ruled out. 321 01:19:19,720 --> 01:19:35,149 Western: And this is a Nobel prize, miss out, and the way we say that in in in most communities uh, I understand it is some communities one say, Oh, yeah, but it doesn't prove anything because of priority. It could be possible. 322 01:19:50,500 --> 01:20:10,330 Western: And that's what. If you you don't, you might not well willing to quant quantum mechanics, but that's what everybody else go for to become. And you you you! You! You want to say, Oh, but then maybe there is another thing. It's not what the mechanics can happen, or show me that theory instead of arguing that uh, oh, something else is possible. 323 01:20:10,350 --> 01:20:15,950 Eduardo Martin-Martinez: So maybe let me compare to cases right, because I think that for for conference, right the case where you find 324 01:20:16,000 --> 01:20:22,199 Eduardo Martin-Martinez: um space like entertainment. So in mind that the two masses are space like separated versus the case. We're not right there. 325 01:20:22,210 --> 01:20:39,000 Eduardo Martin-Martinez: I agree that if you are, if it's, this is I don't think it is as need pik as it may, saying, so let me. I can't give it facetious about this, so the the experiment has given the that the question is, what do you plan to prove with that experiment that we don't know right? What are we learning from the experiment? The fact that 326 01:20:39,010 --> 01:20:48,989 Eduardo Martin-Martinez: the fact that, uh, a classical field cannot be modeling gravity is well known before the experiment, right? Because we have noble results that tells you that you cannot couple 327 01:20:49,000 --> 01:21:06,790 Eduardo Martin-Martinez: one, two system to classical systems. There's a face space definition problem to begin with, So we know it cannot be a classical theory. So that is known, that is, even before doing any experiment. We know already that gravity, the structure is based on cannot be quantum lots of people, but that a lot of people disagree with that, 328 01:21:07,050 --> 01:21:23,700 Eduardo Martin-Martinez: and the No, I don't find it controversial, uh, but but but but there's a difference between theoretical expectation, not theoretical argument. What is this experiment? So that's a key point. So now let me compare to scenario the scenario where you find space like entanglement, 329 01:21:23,710 --> 01:21:32,210 Eduardo Martin-Martinez: virtual dec scenario, where you define non-space like in time you find space like entitlement. This is without making the assumption without making the assumption. 330 01:21:32,240 --> 01:21:55,310 Eduardo Martin-Martinez: That's uh, that's uh. They feel is quantum. The gravitational field is quantum. You prove that the way in which you can model that appearance can only happen by a theory that is one to local and relativistic local. So it's a positive results. So you find that that is a quantum mechanical field of planning. 331 01:21:55,880 --> 01:22:08,459 Eduardo Martin-Martinez: No, the the thing is that they compat that if you find space like entanglement like that and you. So here's the thing. The assumption in that case that I would take is relativistic locality or event locality, if you want, which is not quantum mechanics, 332 01:22:08,830 --> 01:22:36,920 Eduardo Martin-Martinez: what's that? Sorry might be something else which is not quantum mechanics. So you know that that's a difference. So in the case in the first case that I have, I can give you the something else. In the other case I don't think we anybody can give you the other case the other theory without. If I do demand that you satisfy relativistic locality, I can give you a theory for matter and gravity such that there's no gravitational degrees of freedom. There's matters, degrees of freedom, and I prescribe gravity to act in this particular way. This is Uh, this is something I can build. I can build you a theory 333 01:22:37,010 --> 01:22:55,479 Eduardo Martin-Martinez: that, uh, would satisfy this first model if you want. That would be a limit of that mode the model doesn't make. So the money is agnostic about the degrees of freedom of gravity, the first model, whereas the second is not. The second is a result that if you don't find the prediction, then you know that you've allowed Qft. So you see what I mean If you find the negative results. 334 01:22:55,490 --> 01:22:59,290 Ivan Agullo: So, Julia. And then you wanna go ahead with your viewpoint. 335 01:22:59,670 --> 01:23:08,049 Eugenio Bianchi: Uh yeah, it's on the same. It's on the same topic. I I it's a question for uh, for Edward, but also for everybody. Uh and uh, 336 01:23:48,010 --> 01:24:06,849 Eugenio Bianchi: you can just consider the Newtonian potential in this Newtonian potential. Yeah, uh, produces entanglement. We have no doubt about that. The uh electromagnetic potential one over our produces entertainment because it's uh uh, it's one over 337 01:24:36,880 --> 01:24:56,849 Eugenio Bianchi: nontrivial situation uh which can be total about some model of uh, a classical channel for gravity. It's sometimes presented that way, but I want to describe it as a description of a regime. I'm. Referring to the calf retailer, and Millbourne a model of two thousand and fourteen. So what is this? 338 01:25:16,670 --> 01:25:18,859 Eugenio Bianchi: Plus all the way around? 339 01:25:42,470 --> 01:26:01,619 Eugenio Bianchi: It's all the kind of it's a one particle makes a phone call about It's position, and it's a uh distribution of noise to the other particle. It doesn't generate an amendment. Now I don't think that anybody believes that this is our nature works, at least in our circle. 340 01:26:01,630 --> 01:26:03,390 Eugenio Bianchi: But, uh, uh, 341 01:26:09,600 --> 01:26:25,819 Eugenio Bianchi: the regime is uh when you don't just stop the two particles, and you turning interaction. The word is richer. There's uh the uh, the bodies. The two bodies are extended that they don't have a coherent for which that big mass couple studio, the big mass. 342 01:26:25,830 --> 01:26:31,959 Eugenio Bianchi: There is the coherent in the way at Christina described. So, 343 01:26:31,970 --> 01:27:01,920 Eugenio Bianchi: going from the regime where the very simple model. The Bmv model is what matches the experiment to the regime where this uh uh classic of standard model describes the experiment. There's everything in between, and part of it is, how would the experimental is still, as uh isolating systems in part of it is a good as theories we are identifying. Where is the transition? What is good enough to isolate the systems 344 01:27:23,640 --> 01:27:42,530 Eugenio Bianchi: to an amount that we can estimate? We learn something, and we learn something that goes well beyond that one uh elementary quantum mechanics case, because we use these arguments everywhere. Not just in the uh Black Hole Information paradox. We're often with this. The paradox. 345 01:28:55,330 --> 01:29:01,180 Ivan Agullo: Western has the the hand race, and uh, for a while. So 346 01:29:01,690 --> 01:29:03,409 Ivan Agullo: go ahead. We, Francisco, 347 01:29:05,990 --> 01:29:07,599 Ivan Agullo: Go go ahead, Francisco. 348 01:29:08,840 --> 01:29:11,549 Ivan Agullo: I think they're muted here. 349 01:29:11,830 --> 01:29:13,239 Ivan Agullo: I cannot hear you. 350 01:29:17,640 --> 01:29:19,650 Ivan Agullo: We cannot hear you. 351 01:29:19,890 --> 01:29:24,740 Eduardo Martin-Martinez: They they are muted, Ivan. I don't know if you hear me, but they they're muted so maybe that's why 352 01:29:26,280 --> 01:29:28,330 Carlo Rovelli: you you did it right? 353 01:29:28,340 --> 01:29:58,329 Carlo Rovelli: Sorry. Sorry There was a technical problem here. Um, I had a first of all, Thank you to all the speakers uh and uh, i'm particularly interested in uh trying to connect to what you were saying about uh a entanglement um a a, And if in general uh information in gravity, with cosmology as a genuine was doing in the end. But I wanted to ask specifically a question to to Christina, because 354 01:29:58,340 --> 01:30:16,499 Carlo Rovelli: it seems that the problem, the program that she's carrying on and studying the coherence may lead later to some interesting consequences for cosmology. So I know that this is kind of preliminary, and she, Christina was saying, Uh, okay, we have a um 355 01:30:16,510 --> 01:30:39,470 Carlo Rovelli: available, and then the next step is to have a from quantum gravity uh involved. Uh um! But I I would like to ask you, Christina, do you see already applications some way in which your preliminary results can have an effect on the way in which we do cosmology in the way in which we study perturbations, and we understand the classicalizations of the perturbation. 356 01:30:40,790 --> 01:30:58,589 Kristina Giesel: Yeah, I think you mentioned the quantum to classical transition. Of course, this is one one framework where people apply the coherence models. Um, I mean It's a bit the up with that situation, because if we do cosmology, we would like to trace out the gravitational degrees of freedom one hundred and one 357 01:30:58,600 --> 01:31:14,469 Kristina Giesel: erez agmoni. So, uh, you have to carefully think about the what you choose as the environment. But I think a first step could be, and that's also a good work in progress that we consider very simple cosmological models, like maybe Background F. And we've quantized one hundred and fifty, 358 01:31:14,480 --> 01:31:43,350 Kristina Giesel: and then consider some kind of effective model for the environment. Maybe some scalar fields, and then look uh, in a sense, how um how we could could maybe justify semi classical states that we use in cosmological models, because this would also be um a tool to understand better. Maybe the semi classical or Gaussian states use uh if we could derive them dynamically in terms of uh such a the coherence model one 359 01:31:44,930 --> 01:31:57,860 Kristina Giesel: erez agmoni, I mean perturbations. Um could also be. But I would see this rather as a second step, because it's again field theory and it's complicated, and we see already, and for quantization, that the model is very complex, two hundred and fifty. 360 01:31:57,870 --> 01:32:06,290 Kristina Giesel: So I expect, if you do this in the context of cosmological motivation to be uh it even more difficult to handle technically. 361 01:32:08,000 --> 01:32:11,170 Ivan Agullo: And Abai has a question. 362 01:32:11,620 --> 01:32:26,200 Abhay Vasant Ashtekar: Okay, So I think i'll question a comment. Actually so, Christina. And just to continue along what you're saying uh, is the use of the terrible state for the gravitational environment critical? Or could you use for some other state there. 363 01:32:26,820 --> 01:32:37,890 Kristina Giesel: Ah! I think it really depends on the limits that you're considering. So, for instance, these non-relativistic limits which they derived. I think it's It's not so important. What kind of stains you use one 364 01:32:55,070 --> 01:33:13,770 Kristina Giesel: erez agmoni. Yeah, this is, uh I I wanted to say, this: this is a specific thermal state. Uh, but you also saw in the final equation that they derived, and the number that thativistic limit that was proportional to the temperature which I uh defined the thermal state with, and if I choose vacuum, there's no effect anymore. One hundred and fifty 365 01:33:13,900 --> 01:33:30,900 Kristina Giesel: erez agmoni. So uh, that's also reason why we think you have to really look carefully how these approximations are done, because in the full one particle case, you still have a lot of interest in terms. But if you do all the approximate which are also there in the vacuum case, two hundred and fifty. 366 01:33:47,630 --> 01:33:59,360 Abhay Vasant Ashtekar: Thank you. Okay, I I kind of the the the next questions or comments I have to do with the the long discussions that we had earlier on. Uh, 367 01:33:59,800 --> 01:34:00,840 Abhay Vasant Ashtekar: so 368 01:34:01,320 --> 01:34:17,950 Abhay Vasant Ashtekar: I mean first of all, I mean the word degrees of freedom that Edward was using is not clear to me, because normally one things of degrees of freedom and gravity, especially because you're using using linearized gravity as being associated with the transverse priceless boats. 369 01:34:23,720 --> 01:34:25,750 Abhay Vasant Ashtekar: Particles are considered to be 370 01:34:26,060 --> 01:34:40,849 Abhay Vasant Ashtekar: more of a static particles than their interaction, which, in the northern Irelandistic limit would give you. Coulomb Interaction is really going to be coulomb interaction of the of the between the in in the as gravity. 371 01:34:41,010 --> 01:34:45,669 Abhay Vasant Ashtekar: And so I think that the word degrees of freedom is used loosely, and 372 01:34:45,740 --> 01:34:48,060 Abhay Vasant Ashtekar: I mean I. The point is that 373 01:34:48,100 --> 01:34:50,910 Abhay Vasant Ashtekar: if you say something like, well, if if if 374 01:34:50,930 --> 01:35:03,339 Abhay Vasant Ashtekar: if you use all of the kind of field theory that we already know that the feel is contacts. But what we know is quantize is really transverse, priceless ports in the autobiographical field, and so I think that when he is learning something new, 375 01:35:16,620 --> 01:35:22,780 Abhay Vasant Ashtekar: the entire geometry or entire diversity field is generated by matter so only coulomb interaction, if you like. 376 01:35:22,880 --> 01:35:37,360 Abhay Vasant Ashtekar: But even in that case one can see show that you know, even outside matter, you can perform experiments to show that uh this Coulombic degree, if you like, is is is quantum mechanical. Uh, I mean you could. 377 01:35:44,820 --> 01:35:53,430 Abhay Vasant Ashtekar: My last question is really about Eugenio, because I didn't understand completely his viewpoint. Uh you, Judy, are you saying that? 378 01:35:59,390 --> 01:36:00,909 Abhay Vasant Ashtekar: So? That would be 379 01:36:01,060 --> 01:36:05,399 Abhay Vasant Ashtekar: a model that, for example, Eduardo could use as a 380 01:36:25,500 --> 01:36:32,240 Eugenio Bianchi: and uh, the theory of us showing what is the next store that in the approximation is not developed. 381 01:36:57,340 --> 01:37:06,649 Abhay Vasant Ashtekar: Okay, so, then, is this what you're saying that in answer to Carlos question it, Eduardo would say that. Well, even if you see this entanglement uh 382 01:37:06,860 --> 01:37:20,120 Abhay Vasant Ashtekar: uh in in the in, not not the case where there's space like separated, but the usual you. If we solve this and development, it could be, We know that it's not classical relativity. But, for example, it could be this model as opposed to quantum mechanics. 383 01:37:21,260 --> 01:37:24,920 Eugenio Bianchi: So this specific model produces zero entertainment, 384 01:37:25,190 --> 01:37:32,640 Abhay Vasant Ashtekar: I see. So if we saw an entanglement, then we would say that this board is also going. Now, Okay, this is what I want you to understand. Okay, Thank you very much. Okay. 385 01:37:32,790 --> 01:37:44,029 Eduardo Martin-Martinez: So so it So I i'm saying this as well. If that model in particular will definitely be this proven by a Vm. The experiment. There are other models. For example, you can do a passive quantum gravity, which is a lot of freedom to choose 386 01:37:44,040 --> 01:37:57,730 Eduardo Martin-Martinez: the stochastic sector of the dynamics. If you want to the computational field, you can fit. If you with a shoe horn. I can fit a model for sure. That is not quantum. So so not classical. Obviously it's going to be stochastic in some way that is not trivial 387 01:37:57,740 --> 01:38:17,150 Eduardo Martin-Martinez: that can describe the experiment. Basically, that's the difference between a fossil f falsifying experiment versus an experiment that is open to many models, Right? The space like one. It's a falsifying experiment about Qft in the low energy sector of gravity. So you do. The space like separated one. If you don't find what is predicted. You are falsifying 388 01:38:17,420 --> 01:38:22,670 Eduardo Martin-Martinez: that there's a qft in the low energy sector of gravity that you can discard linear gravity in 389 01:38:23,130 --> 01:38:33,839 Eduardo Martin-Martinez: um. If you do, if you find in time in the Vm. The experiment, all that you're saying is that all the models that are based on to describe gravity are discarded. 390 01:38:33,890 --> 01:38:43,679 Eduardo Martin-Martinez: That's what you're saying if you're doing that. So gravity established a quantum channel. Now, in the discussion about the the existential degrees of freedom I was going. I was using these terms in the sense of okay 391 01:38:44,140 --> 01:39:02,030 Eduardo Martin-Martinez: understanding quantization in the canonical sense, right? Because I mean, i'm in with gravity as well as I'm. Like. I have a face facing weak gravity. I have a face space for gravity, and there's some sort of quantization map uh that uh maps my uh dynamical functions to uh self. I join representations of operators in a heel of space. 392 01:39:02,040 --> 01:39:16,929 Eduardo Martin-Martinez: And uh, my P. Some brackets go to commutators in that sense, because I'm. In the week in the week. Gravity sector. But what is Condes? There is a transfer space list most, and has nothing to do with this uh, with this Coulombic mode, which is really what you have to 393 01:39:16,940 --> 01:39:34,889 Abhay Vasant Ashtekar: for me. This there's a problem with this whole analysis of the experiment. I don't mean it's not worth it or something. But if you take it very seriously, it it seems to be a little bit hodgepot picture right? I mean, in the sense that the one is talking about. Uh in an analysis of experiment, because one is talking about, you know, point particles 394 01:39:34,970 --> 01:39:48,640 Abhay Vasant Ashtekar: and their wave functions. And somehow one other wave functions. I mean, are you talking about this part? I am fine. I'm saying that these are relatistic particles, and and in a regime in which there is no particle creation you can put that in, 395 01:39:48,650 --> 01:39:59,799 Abhay Vasant Ashtekar: but still you should treat them relativistically, you know. Talk about one particle sector, and not point particles coupled with this 396 01:39:59,810 --> 01:40:17,549 Eduardo Martin-Martinez: that can be done as well, and that they wouldn't change the results I can. That is easy to actually include to three third particles in a quantum field theoretical way as well, and even without restricting to a one particle sector that can be done, it would be very similar; but allowing for particle creation. No, I mean that could be completely I could 397 01:40:17,560 --> 01:40:22,380 Eduardo Martin-Martinez: I could if I wanted. I can include. If you want, I can go ahead. 398 01:40:28,130 --> 01:40:58,110 Eduardo Martin-Martinez: And Then what? What entanglement are you talking about? Of course, of course you would have. You have a state of like quantum field, say a with packet kind of in mind that you create a four-way packet one particle in that sense that's allowed to do. And then you have some device that you can model, and people know how to model these things in the low energy sector that creates a superposition of paths. And there's the interaction of the model of that. Uh that's a device that creates the path superposition. That doesn't conserve particles, for example, in only in non-relativistic approximation. It does so you could model you're gonna go a little bit away from the one person, 399 01:40:58,120 --> 01:41:18,139 Eduardo Martin-Martinez: and you could do the full treatment, of course, that way. But you can. Actually you you! You're claiming that your calculation, and we just specify all this approximate basis systematically, that not one or and is it published already? No, no, no, not at all. I mean. This is not that it can be. It's technically complicated, but what I mean is coming on. But I mean, I get it. We We know how to model those steps in particular. 400 01:41:18,500 --> 01:41:29,679 Eduardo Martin-Martinez: Um, I do have a question as well for for for for Christina. If if that's okay, I don't know if it's the time. That's okay. We are um getting out of time, but that maybe you last question. 401 01:41:29,820 --> 01:41:40,269 Eduardo Martin-Martinez: So so, Christina, there's one thing I I I enjoyed your your presentation a lot. There's one thing that is, uh, uh, commonly looked at in from the point of view of relativistic content information, right? 402 01:41:40,280 --> 01:41:54,220 Eduardo Martin-Martinez: Uh, when people like you mentioned the Anastoplas. Who uh Blenco you want uh models, and in particular, in a couple of someday look the the the these families of models um have some issues that I've been recently looked at, 403 01:41:54,230 --> 01:42:13,799 Eduardo Martin-Martinez: which are related to the fact that uh, there's no console. Some approximations on our zoom and are okay to do like. For example, we're talking about, but not only rotating with approximation in particular, are extremely incompatible with um uh the relativistic nature of the theory. This then looked at this, for for we're talking to youft now here, not not driving 404 01:42:13,940 --> 01:42:22,970 Eduardo Martin-Martinez: um. And I wonder whether uh, that's something that we're asking like typically to see if those approximations work, you have a framework in which you derive 405 01:42:29,410 --> 01:42:52,500 Eduardo Martin-Martinez: um. So again, there's some recent work uh discussing that uh that tip that the models of that of the kind of uh, the who and a stop those kind of model have these issues right? Is that something that's uh would affect you or W. Or you at all, as and because, or do you have good reasons to take those approximations and non-relativistic approximation uh rotating with approximation. What What are, What is the 406 01:42:52,510 --> 01:42:54,220 Eduardo Martin-Martinez: that? Is it Because 407 01:42:54,310 --> 01:43:00,819 Eduardo Martin-Martinez: do you have a good reason to make them? Or or is the are they done without uh justifying them typically 408 01:43:01,560 --> 01:43:25,630 Kristina Giesel: erez agmoni. Um. So I think this is one of the ideas we had in mind when we started that we really wanted to start from from from the linearized action, and then see um! What do we have to require in order to get some mass decreation? And um I mean. Of course, we also use the spawn approximation to have some manageable last situation in this sense. And yeah, I agree. We could debate that one hundred and fifty 409 01:43:25,640 --> 01:43:44,429 Kristina Giesel: erez agmoni um the non-relativistic one, I mean. I would rather say these kind of models are. Very. They're not rich in in the sense any more that I would like them to have because they are so simple. I couldn't see any fug inspired features of that. So one hundred and one 410 01:44:26,410 --> 01:44:27,620 Kristina Giesel: um 411 01:44:36,450 --> 01:44:49,079 Kristina Giesel: Erez agmoni program. Uh: yeah, people could work on, And I think people will learn something on the way in the sense how valid up approximations. Or maybe, if you do some, they are justified at the later stage, one hundred and one. 412 01:44:49,390 --> 01:45:19,309 Kristina Giesel: Yeah, the the the the literature is that thing at that point in Qft. I'm. Talking right that the coherence in uft it's certainly at a point that people are finding problems with assumptions that are done kind of by default that are inherited from the coherence in non-relativistic setup. So so yeah, there's I mean have A. D qed that I also use this Um, But again, I mean uh even writing down the operators i'm using is something which is a bit out on fox space. So it's already starting there. And uh, I guess there's a lot to do. 413 01:45:26,950 --> 01:45:40,549 Eduardo Martin-Martinez: There's a big difference between finite volume, my an infinite volume. Uh, do do you see that it? I? It's what you were also referring to it one right 414 01:45:40,840 --> 01:45:57,469 Kristina Giesel: erez agmoni. Yeah, I mean already by choosing the the thermal state right? I mean, uh, if you do this on fox space. It's It's very uh, yeah, difficult, even not possible. You have to work with Kms states. And in the final volume case, I mean, you can just choose a gift States, and it goes through one hundred and fifty, 415 01:46:05,550 --> 01:46:13,650 Ivan Agullo: very good, and and a table of raise the hand. So uh, maybe last uh intervention, 416 01:46:14,310 --> 01:46:23,190 Western: just a uh, yeah, just a short comments. Um, the final Wheeler theory. 417 01:46:23,460 --> 01:46:34,210 Western: It's a formulation of Qd. Where uh one thing at the at the field, as generated by the particles only. It's very similar to what to do out the same 418 01:46:34,810 --> 01:46:49,719 Western: um one as impression that the only the only degrees of freedom are the particles in the field is just determined by the particle. Uh. But that's wrong in in in in in a specific sense, which is a following. If you take the cost on time slice, 419 01:46:49,780 --> 01:47:01,249 Western: which is where you see where the degrees of freedom are, and you say the what the position of the particle is on the time slice that does not determine 420 01:47:01,580 --> 01:47:09,170 Western: the state of nature, because the state of nature, of course, depend on where the particles were before 421 01:47:09,630 --> 01:47:21,150 Western: so on a constant time. Slice. If you want to give data, you have to give the position of the particles plus more, which can be either where the particle with before or the field there. 422 01:47:21,840 --> 01:47:23,469 Western: So um 423 01:47:23,780 --> 01:47:30,029 Western: is not at all true that by just looking at retarded potentials 424 01:47:45,600 --> 01:48:01,570 Western: mit ctl, and I mean it's just not what we usually mean by degrees of freedom. There are things that can be in superposition, because you can have the two particles, not in superposition, say in a point. But they? Where is the position in the past? That so? The field at some time is in superposition, and the Hilbert space one 425 01:48:01,580 --> 01:48:08,099 Western: of a five minute wheel theory is not just a fuel in the space of the particles much richer, so that's where the superposition is. 426 01:48:13,590 --> 01:48:30,660 Eduardo Martin-Martinez: I do you have the right. So so um their pointer. That is important, I think. Uh It's uh they agnostic. The The first model I presented is completely agnostic about what's the dynamical sector of gravity whatsoever in that sense. 427 01:48:30,670 --> 01:48:45,199 Eduardo Martin-Martinez: So where the degrees of freedom really live or not, it's totally agnostic. So that's the point. I mean. You can fit a lot of models. Let me put it just families of models that they, the set of models for which you can actually find in time in the Vm. The experiment. 428 01:48:45,210 --> 01:49:00,110 Eduardo Martin-Martinez: It's very large, and you still have a lot of room for models that are not necessarily quantum. So particular models may have these. I, in fact, I believe that Carlos. So in in essence I agree. I believe, that eventually you can disapproval every single one of them. But I was focusing on finding 429 01:49:00,130 --> 01:49:14,349 Eduardo Martin-Martinez: um, but we were focusing on finding a particular redeem in which uh, all models uh that uh are not uh based on the assumption of a low energy sector. This qft can be this proven in the sense that it can falsify. 430 01:49:14,360 --> 01:49:25,190 Eduardo Martin-Martinez: So the the space like one, if you want can falsify the models for which you have a low energy sector of the theory that um uh, it's a qft for uh for gravity. 431 01:49:25,270 --> 01:49:35,870 Eduardo Martin-Martinez: But I agree. So that the point is that in principle just find in and we in Vm. You can fit a lot of models. Uh, maybe those models are all far-faced, but it's such a big set 432 01:49:35,880 --> 01:49:53,860 Eduardo Martin-Martinez: that they claim whether you've seen entanglement is connected one to one to experimental proof of quantum gravity is what may not be so direct, so I guess I guess it's. It's a matter of a bit. That's it. That's what it is. I'm not developing it. Everything else is facts. I think I think all that we agree with is, it's actually agree on this facts. 433 01:49:53,870 --> 01:50:01,210 Eduardo Martin-Martinez: But what is a matter of opinion is, what would you consider proof of uh experimental proof of quantum gravity? 434 01:50:01,220 --> 01:50:17,260 Eduardo Martin-Martinez: And uh, and what you need to assume in order for the experiment to be connected directly to to quantum gravity, so I guess the whole point can be summarized, and there's a larger set of theories that what could in principle fit in a model that is agnostic about the gravity sector. Like the first model I presented. 435 01:50:17,690 --> 01:50:31,650 Eduardo Martin-Martinez: That's pretty much what it is. It's very deep. So superposition in the sense of this some notion of Hilbert space for gravity, and I have a quantum super position in the same way as I have for every other single matter. Field. That is the thing I don't think you can prove with B and the entanglement 436 01:50:31,720 --> 01:50:37,069 Eduardo Martin-Martinez: as proposed. So that is, I guess that's the extent of the client. 437 01:50:37,240 --> 01:50:56,010 Ivan Agullo: Wonderful! I think it is wonderful to have all these different viewpoints, really, eh? And reaching that was the goal of this panel. And I thank you, Eduardo in particular for for for participating, and also, of course. So Jenni and Christine a couple of for the government's Abaya and uh Crunches kind of the rest. 438 01:50:56,020 --> 01:51:04,800 Ivan Agullo: Uh, I think it was uh a fantastic and and and hopefully, we will have more many more discussions like this in the future. 439 01:51:05,340 --> 01:51:12,259 Eduardo Martin-Martinez: Thank you. Thank you and I really appreciate it. And thank you, Pablo and and and everybody else who participated in this 440 01:51:12,290 --> 01:51:20,450 Eduardo Martin-Martinez: in this discussion. Uh, because I think it's really good for for us as well to be exposed to. Uh this. Well, thought arguments as well. Thank you so much. 441 01:51:20,500 --> 01:51:22,550 Eugenio Bianchi: Thank you for organizing this 442 01:51:22,740 --> 01:51:25,139 Kristina Giesel: wonderful Thank you.