Piotr Chrusciel: Okay, good.
Jorge Pullin: Good so crucial will speak about gravitational wave guys the other.
Piotr Chrusciel: Okay, good so.
Piotr Chrusciel: Good morning, or afternoon everyone good afternoon if you're in jenna but then morning to some of you.
Piotr Chrusciel: When I was invited to give the start I gave it a bit of thought, because I thought that if people hear that i'm giving experimental talks in a quantum gravity me not my reputation, with growing so.
Piotr Chrusciel: So I was a bit worried and we are we're both invited to give this talk with Bobby and I think he saw that night.
Piotr Chrusciel: Anyway, so.
Piotr Chrusciel: Since i'm here at tech you're about to tell you about some gravity wave wave guide.
Piotr Chrusciel: This is work done, we seen something.
Piotr Chrusciel: called the research platform for testing and the quantum and gravity interface at the Faculty Vienna and the slides i'm using here are all a lot of the voter and tonight's meeting.
Piotr Chrusciel: So what is this testing the serious business mean right, so this is testing quantum gravity interface, by the way, can you see my laser pointer please.
Jorge Pullin: Yes.
Okay.
Piotr Chrusciel: This is called a Vienna university research platform, which means that we get some extra money from director to do what we're doing this involves several groups, so a group of 50, which is an expert in untangle photons.
Piotr Chrusciel: group of markets aren't which studies matter waves group of.
Piotr Chrusciel: mark, which has been my nano mechanical devices group of brookner who looks at causal structures and quantum physics and we even have a colleague from the Faculty of astronomy.
Piotr Chrusciel: And the big open question is, how does gravity act on quantum systems that's, the question we wanted to address as a consortium of all these teams and the sub question i'm going to talk about today's how.
Piotr Chrusciel: Well, a little provocatively How does it feel time and also how do entangle photons time so well let's be more precise, or less.
Piotr Chrusciel: romantic How does grove it it masters quantum systems, including a quantum entanglement.
Piotr Chrusciel: So the question is.
Piotr Chrusciel: Especially, how do we test this we have tested this and, of course, we have a test of classical physics in newtonian gravity that's something to do we have a lot of tests of classical physics interacting with general activities are the hottest of Dr we have some test.
This.
Piotr Chrusciel: Some experiments testing quantum mechanics in newtonian gravity and i'm going to mention them shortly and the point that we.
Piotr Chrusciel: wanted to make and the claim is that none of the experiments which have been performed to TAO today show unique signatures of general relativity and quantum mechanics.
Piotr Chrusciel: In a single experiment, so, in other words, I experienced quantum mechanics and Newton and gravity.
Piotr Chrusciel: Now experiments in general relativity and classical physics, but there are no experiments which do something which is specifically general relativity and specifically quantum mechanics and our proposal is that maybe photonic quantum systems or the right way to.
Piotr Chrusciel: test.
Piotr Chrusciel: Our theory yeah.
Piotr Chrusciel: So let me this is about time and quantum mechanics and generativity so let me brand very quickly about the some classical test of general relativity and i'm going to go.
Piotr Chrusciel: All of them, but one which is gravitational redshift which is going to be relevant to the experiments in time talking about started or predicted already by Einstein in 1907 well before generativity using the equivalence principle.
Piotr Chrusciel: first test in 24 by eddington who suggested that it could be tested by looking at spectral lines of light doors and so started in 25 and culminating in 2005.
Piotr Chrusciel: They found red guy experiment I don't think I need to explain what it is to anyone in this audience.
Piotr Chrusciel: Half allocating they put a clock on an airplane and tested both the special relativistic time dilation and the general relativistic.
Piotr Chrusciel: Time snowing or all time accelerating whatever you call this the accuracy of 10%.
Piotr Chrusciel: Improved in 76 using rocket flies by vessel and friends to.
Piotr Chrusciel: accuracy of one party in about 10 to minus four.
Piotr Chrusciel: And the best test of the gravitational redshift that we have so far is a.
Piotr Chrusciel: Success of failure, the failure was the launch of the GPS satellite European GPS satellites Teresa in Atlanta in 2014 the launch didn't work quite as it was planned and instead of.
Piotr Chrusciel: The spot satellites would have gone to Nice.
Piotr Chrusciel: spherical beach instead they went to a particular ones, and that was a blessing for us, because then.
Piotr Chrusciel: The satellites are evolved being in a very in gravitational field, because of the electricity of the orbits rather than on a circle, and so you can then.
Piotr Chrusciel: Do experiments will test the redshift all the time.
Piotr Chrusciel: Local time versus Eric celestial time.
Piotr Chrusciel: versus less time on onboard the satellite, these are the results published by this group in 2018, so this is a blue points of the data points the yellow is the GR prediction.
Piotr Chrusciel: The residuals are here, if you look at the residuals the three orders of orders of magnitude smaller than than the signal itself, and this gives a.
Piotr Chrusciel: test of.
Piotr Chrusciel: gravitational redshift at accuracy in one part in in tend to minus two five, so the best results so far.
Piotr Chrusciel: When talking about classical best of general relativity Let me mention this one, which is often mentioned because it's mentioned as the record holder of.
Piotr Chrusciel: distance between the clocks.
Piotr Chrusciel: Namely 30 centimeters the previous ones, obviously involved a large large distances so here in this experiment reported in 2010 two and France, said that they moved two clocks by 30 centimeters and they were able to measure the difference of time of.
Piotr Chrusciel: The rate of flow of time and decides.
Piotr Chrusciel: That personally when I look at this data, here I So these are the data right the blue lines, the blue points are coming from the lower clock and the red points are coming from the upper clock.
Piotr Chrusciel: Well, if you look at their bond the red points and remove a couple of points here and I.
Piotr Chrusciel: My feeling is that the straight line is actually a very good teacher to to these data points so, in other words.
Piotr Chrusciel: Obviously, we think that there should be an effect and i'm not completely convinced that they really demonstrated it with this displacement of 30 centimeters, so I think that lab scale displacements or still an open game in this business.
Piotr Chrusciel: Now let me mention another effect, whether the redshift with the Scottish up your effect and, as far as i'm concerned it's hard to say whether these are different effects or not I mean calculation for me is the same you're just looking at curves in space time and compare the.
Piotr Chrusciel: Time house of time flows along these things never there is this another name for this, this is called track your effect the experiment is it you sitting on us, you sending raider into.
Piotr Chrusciel: The planet in this case Venus and.
Piotr Chrusciel: A strong raider game with reflected comes back and you measure the time it takes to go back and forth, and you compare this to the time.
Piotr Chrusciel: That it would have taken to if space time was binkowski between these things so so you get a prediction accuracy with up to 10% with gen activity, the one should say that there was a bit of a discussion.
Piotr Chrusciel: How they experiment was biased by light traveling through near the sun in the region, where there is a corona this plasma there is all kinds of stuff How does this affect.
Piotr Chrusciel: The results and so forth, in case, one gets something which looks very much like generativity up to 10% and.
Piotr Chrusciel: By now, we can do much better because one can repeat this experiment not sending light from us to Venus but sending light to both first the weekend about probe and, finally, the finest experiments seems to be like sent to communication with the Cassini.
Piotr Chrusciel: spacecraft where the accuracy of one party 10 to five was achieved for the shapira effective similar to the accuracy, you get for the rich lift weights, with the GPS satellites.
Piotr Chrusciel: Now I, the reason I listed all these things, was to make it clear that this is all classical music and classical flight flying back and forth, and we trying to measure properties of classical light now, what about one from physics.
Piotr Chrusciel: Well, the first quantum test of eternal gravity is the famous cow experiment cow being colella over hauser and burner.
Piotr Chrusciel: published in 75 and the idea is to the following you set up a neutron interferon and you send neutrons in a machine which deflects them, so you create a beam splitter and then you look at another it's another.
Piotr Chrusciel: place where the beams are really.
Piotr Chrusciel: Well reconnected redirected together, and you have Newton detectors behind this and you count how many nutrients get in there, and how does gravity enter here well you rotate this machine.
Piotr Chrusciel: along its axis, and this is constructed in a way, then when it rotated then one of the beams will be higher than the other one, so, in other words, you can put your machine, so that they both beams out of the same height and then you can rotate it and one of the beams goes higher.
Piotr Chrusciel: Well, you just take your favorite shredding equation throw in a newtonian potential constant potential in the gravitational field.
Piotr Chrusciel: You get can calculate what you should see after this experiment and you get a very good experiment.
Piotr Chrusciel: Agreement with the schrodinger equation, with the newtonian potential right, so no general relativity here, even though one could make the point that, of course, one interpretation possible is that when these guys travel different heights.
Piotr Chrusciel: Time.
Piotr Chrusciel: flows differently on the lower arm and the upper one, and this is the dinner a statistic explanation of the difference of the time of arrival and therefore the difference of faith shifts.
Piotr Chrusciel: And Well, yes, you can make an argument like that, but then it makes sense to invoke outcomes rather and say, well, if you don't need to enroll activity but Newton gravity's nothing.
Piotr Chrusciel: don't come, saying that this is a test of generated.
Piotr Chrusciel: So this is certainly a beautiful experiment, but it's not a test internal activity.
Piotr Chrusciel: Another experiment in the same spirit, about 2000.
Piotr Chrusciel: Well, in the same spirit in that you're using quantum mechanical system.
Piotr Chrusciel: and evolving in a gravitational field, so you have something which is called a.
Piotr Chrusciel: cesium items fountain which sends items up the items on Monday plated using laser beams in a very sophisticated way.
Piotr Chrusciel: You put your experiment in the neutron.
Piotr Chrusciel: In the shooting equation is a nutrient potential you get very good.
Piotr Chrusciel: Well agreement with the theory again.
Piotr Chrusciel: People have put forward interpretation that has to do with a.
Piotr Chrusciel: Different flow of time at different heights well, I think that this is a bit exaggerated for this experiment, if you can explain it with treating the equation.
Piotr Chrusciel: Let me.
Abhay Vasant Ashtekar: mention one last.
Abhay Vasant Ashtekar: auriemma justice so one could even be more precise right, because by example in the experiment with the neutron.
Abhay Vasant Ashtekar: could actually.
Abhay Vasant Ashtekar: Say that well I could calculate and analyze it just using the direct equation in the.
Piotr Chrusciel: In this.
Abhay Vasant Ashtekar: Space time and just showing you the question and see that the effect is much the change in using shorter equation, what is the equation of course space, time is.
Abhay Vasant Ashtekar: Is of certain order of magnitude, which is way beyond the position of this experiment.
Abhay Vasant Ashtekar: And okay.
Piotr Chrusciel: So, so I.
Piotr Chrusciel: Never have this calculation, so can you send me very fancy so if there's a calculation.
Piotr Chrusciel: calculation.
Abhay Vasant Ashtekar: With the experiment came I did it myself, but I had.
Piotr Chrusciel: Oh okay.
Abhay Vasant Ashtekar: Do you do do it again, but it's not difficult, I mean one.
Piotr Chrusciel: Okay, good expired, so in that case, one doesn't do it in walk outcomes.
Abhay Vasant Ashtekar: Is that one can just say well it's not because of this equidistant experiment doesn't see the distinction between the two.
Piotr Chrusciel: Right, I mean so yeah so so yeah Of course there is a question of accuracy, because presumably good.
Piotr Chrusciel: accuracy high enough, you could.
Abhay Vasant Ashtekar: Start some right exactly but, but the one does not try.
Piotr Chrusciel: This one doesn't do this, and this one doesn't do either and.
Piotr Chrusciel: Let me mention one last experiment which.
Piotr Chrusciel: is not directly related to to this flow of time business but still a beautiful experiment which involves neutrons so quantum objects in a gravitational field so in Vienna we like to call these experiments.
Piotr Chrusciel: Experiments because that's a colleague here, so he was a collaborator on on this paper which first offer, and this is key.
Piotr Chrusciel: And he's been involved in this experiment and several other along the same line, and so what what is the experiment about well you send neutrons between two.
Piotr Chrusciel: plates.
Piotr Chrusciel: So so and these plates is one above the other and therefore you have in your gravitational potential between these two plates, so thank well wait a minute i've done a.
Piotr Chrusciel: quantum mechanics point one, so I have to infinity potential walls and the linear potential between the walls, I can solve this problem for.
Piotr Chrusciel: eigenvalues and, indeed, you can do it and it's one of the elementary but one of the cases where you can get explicit solutions.
Piotr Chrusciel: And now the problem in so far every functions are explicit actions, but so we get a spectrum for this problem with every functions which have.
Piotr Chrusciel: Safe you're going height and the potential is varying linearly and that's the energy levels, you can get and indeed in this paper they reported that they get they can see this energy that also the output of this experiment this paper goes back to 2002.
Piotr Chrusciel: very interesting variation of this experiment in 2015 where you still have your.
Piotr Chrusciel: To.
Piotr Chrusciel: sell so you still send the your your your neutron beams between two plates, but then.
Piotr Chrusciel: You let the beam run above.
Piotr Chrusciel: vibrating plate, so this red thing is vibrating now because this thing is vibrating.
Piotr Chrusciel: It induces transitions between the energy levels in the way you know, maybe not from quantum mechanics one one but one or two to one or something like that.
Piotr Chrusciel: So you use the standard transition rules that you get from a standard quantum mechanics in a perturbation skin and you can measure again agreement with.
Piotr Chrusciel: With this of what you see at the end with with the theory.
Piotr Chrusciel: Again shredding equation with between your potential beautiful experiment very difficult very precise yes.
Carlo Rovelli: Yes, did you do medical issue, I think I think we have time this is.
Carlo Rovelli: Of course I this is going to say I agree with everything you said, but you, you talk about the outcome, racism and then.
Carlo Rovelli: See, if you agree with this, which is slightly different take on what you say.
Carlo Rovelli: If the question is to test general relativity Of course these things don't test generativity I percent with you that same effect is obtained the segment infinity limit Tony Tony.
Carlo Rovelli: But if the question is how to better think about this, what goes on.
Carlo Rovelli: I mean generative it has a lot of independent support from from elsewhere so.
Carlo Rovelli: When I observe a phenomenon earth I don't say I don't need Copernicus I I don't need you to ptolemy is good enough, so I think telling Mike because of our can razor.
Carlo Rovelli: I say that my best understanding of the world, so far is with Newton was that autonomy, so I think that this way, so I, I would say that maybe i'm too much of a relativist but.
Carlo Rovelli: classical genetic which is sufficient to confirm from elsewhere, then I prefer to seek at say they is interference effectively sets in terms of different time.
Carlo Rovelli: of flight rather than on a sort of peculiar limit, which is newtonian potential that's not in contradiction with what you say, but it uses the outcome, based on the different manner.
Carlo Rovelli: Would you disagree with that.
Piotr Chrusciel: So i'm not sure if I understood correctly, but what you're saying is that all this is compatible with Dr right So in this sense it tests your.
Piotr Chrusciel: But what i'm saying is you don't need your for that.
Piotr Chrusciel: yeah so we know that the weekly meeting Dr is Newton theory so we're happy with this right we don't know what the.
Piotr Chrusciel: Week limit of quantum gravity is because we don't know what quantum gravity is that this has nothing to do is quantum gravity i'm talking about.
Carlo Rovelli: To go into gravity gravity sure acting with quantum systems.
Piotr Chrusciel: And these experiments show that is a question which makes sense and it works so.
Piotr Chrusciel: At the newtonian level certainly does and therefore presumably at the general district level and what i'm saying that we haven't checked now no experiments which go beyond the newtonian regime here and the point is to propose one and that's what i'm going to.
Piotr Chrusciel: To do you know what follows that, then I don't know if if that's.
Piotr Chrusciel: What you had in mind here but.
Carlo Rovelli: Well, maybe this is a longer discussion so.
Carlo Rovelli: yeah let's let it open I don't think we.
Carlo Rovelli: disagree, but I.
Piotr Chrusciel: don't.
Piotr Chrusciel: yeah yeah okay.
Piotr Chrusciel: Good.
Piotr Chrusciel: So yeah so, then the point is okay so let's.
Piotr Chrusciel: Take as a quantum system photons and protons single photons entangled photons assembly quantum object and there's no newtonian model for them, so we need a equations like maxwell's equations inequalities time we suddenly goes beyond Newton theory and that's.
Piotr Chrusciel: Our point here that, if we do this, and then, of course, the question is protein sufficient.
Piotr Chrusciel: accuracy in the experiments to get to a.
Piotr Chrusciel: Certainly general relativistic regime, because you can still argue that when when we see in such a week field that.
Piotr Chrusciel: One is testing a theory which is essentially a metric metric interaction of light and the metric is whatever it is doesn't have to be generativity could be many other metrics so.
Piotr Chrusciel: When would need really to go the very precise experiments to be able to discern generativity rather models and that's going to be and I hope the future of this field better.
Piotr Chrusciel: So so let's see so we talking about photonic quantum interferometry, and this is to be supposed to be a my colleagues like to think of it as the quantum version of the shapira effect.
Piotr Chrusciel: Since this involves redshift you can think of this as a quantum version of the gravitational redshift effect, and I say what he said I don't really see a big difference between calling this Shapiro or gravitational redshift or anything like that I just do this as.
Piotr Chrusciel: a test of quantum field theory interface time quantum field theory of a photon you know catch this time at this level, because space time not being very good.
Piotr Chrusciel: But still being a bit cost, so this is a paper published about five years ago, which proposes an experiment involving photons, which is supposed to test.
Piotr Chrusciel: The maximal equation because metric quantifies Max equation because metric.
Piotr Chrusciel: With several hotels that's one of these that's my first paper on an experimental.
Piotr Chrusciel: topic so my understanding is that if you look at the list of the authors and the last ones are those that did nothing there and.
Piotr Chrusciel: The first person is the one who really did something here so feel the vita who is probably the driving force behind all this was kind enough not to put me in the last place of faith.
Piotr Chrusciel: In any case, I was involved in this experiment in the designing of this experiment and, what is this supposed to do well, you send laser light.
Piotr Chrusciel: into something which is called him mark tender interferometer that's the main for this kind of devices, and so the idea is you split your beam into two and.
Piotr Chrusciel: something happens, meanwhile, and then you recombine the teams and you see what happened at the end, so this neutron CW experiment it's actually a mass enter experiment with with neutrons interferometer is neutrons.
Piotr Chrusciel: So yeah when you, the point is that this arm of this interferometer is lower than this one, and therefore the photons traveling here travel.
Piotr Chrusciel: Whether traveling in the higher arm traveling in a different potential than the photons traveling in the lower and therefore.
Piotr Chrusciel: Since you know that there is gravitation redshift tilting the frequency will be shifted or you know that there is such a pure delay, so therefore the time will flow differently any case, no matter how you.
Piotr Chrusciel: What names you put on it at the end, there should be a phase shift when these teams recombine here, and then you can certainly calculate this and that's the formula.
Piotr Chrusciel: So what.
Piotr Chrusciel: In order to understand the setup and to think of whether it makes sense let's look at some numbers here.
Piotr Chrusciel: So when you.
Piotr Chrusciel: calculate you can calculate the change of the waves vector in this system, it is something called the way vector and whatever the formula is just ignore it, for the moment, what is important is this number here, then there is a change of a wave vector which is.
Piotr Chrusciel: About of this order.
Piotr Chrusciel: In this experiment and, if you want to.
Piotr Chrusciel: get a phase shift out of this phase shift is rough it is actually not quite the right equation, but at the simplest equation would be just change of the way vector times the length of the.
Piotr Chrusciel: arm yeah.
Piotr Chrusciel: Well, if you take this difference of fight between the arms to be of the order of one meter and you want to have a face shift with this order tend to minus four ads which my colleagues here in Vienna claim they can measure.
Piotr Chrusciel: Well, they claim actually they can measure tend to minus five so tend to minus four is what you need to get a decent.
Piotr Chrusciel: signal to noise ratio, well then, you need hundred nanometers Okay, so if this is hundred kilometers, and this is one meter, then you should get something which.
Piotr Chrusciel: can be detected with the present technology.
Piotr Chrusciel: In quantum optics.
Piotr Chrusciel: Well, how do you get 100 kilometers yeah you could say well why don't you ask the late Lego guys to move the second arm not orthogonal II, but a meter higher than the first arm and then.
Piotr Chrusciel: Going 30 times they can force is actually what we need so.
Piotr Chrusciel: But I don't think they want to do that, so the idea is well why don't we put here a wave right.
Piotr Chrusciel: So you put a wave guide between this murals and you can have hundred kilometers on your desk because can just call you wave guide and hundred kilometers will read.
Piotr Chrusciel: It technically they say it's 20 the decibel loss, which means that, after hundred kilometers if you send in hundred.
Piotr Chrusciel: photons here you're going to get one adult put right so 1% transmission rate 99% losses and that's something that they can live with right so.
Piotr Chrusciel: They can send in enough photons here so that to get this detection at one person transmission rate hundred kilometres two weeks and hundred kilometres.
Piotr Chrusciel: Which one meter he, of course, if you.
Piotr Chrusciel: put this arm on.
Piotr Chrusciel: Top of a very high tower on a satellite, then this changes the numbers.
Piotr Chrusciel: helps you quite a bit, but.
Piotr Chrusciel: let's talk about tabletop experiments now so just put two.
Piotr Chrusciel: To wait guides here.
Piotr Chrusciel: and try.
Piotr Chrusciel: To do it.
Abhay Vasant Ashtekar: But.
Piotr Chrusciel: He I saw one yes.
Abhay Vasant Ashtekar: For like Oh, I mean the thing is that.
Abhay Vasant Ashtekar: You don't have to do things on the top of each other, because we can just I mean the the tube is much more than a meter so you could just have one one beam at the top of the tube are towards the top tube and one at the.
Piotr Chrusciel: Bottom put another been there right but I I, I think that if I told the guys to do this, maybe just they probably yeah.
Abhay Vasant Ashtekar: there's a be.
Piotr Chrusciel: Okay, to have.
Piotr Chrusciel: it's a what.
Piotr Chrusciel: A beta of a disruption of their experimental setup but yes, in principle, why not right, I mean if you could do this if you're in vacuum, if you that would solve a lot of problems here.
Abhay Vasant Ashtekar: Right so it's just it will not be I mean it'll just be it will be just a laser beam and not expecting another Armani can attack that's right, I mean you're saying that well one particular are put them talk to each other.
Piotr Chrusciel: Well, you still need you still need two things to compare right.
Piotr Chrusciel: Because otherwise what what, how do you know.
Piotr Chrusciel: Right, so you need to answer so.
Piotr Chrusciel: yeah different heights right.
Abhay Vasant Ashtekar: So in the in the same arm.
Piotr Chrusciel: yeah good to be emceeing.
Abhay Vasant Ashtekar: today's right exactly and that that's what you would compare and so it could be just the two lasers, is what is needed it's not that to do different vacuum tubes that are needed for collaborative but Okay, please go.
Piotr Chrusciel: Right okay so good so so, but our idea is to do it on a tabletop anyway, and so this is a version with actually three arms.
Piotr Chrusciel: So you see that one wave guide is sitting lower than the second sitting lower than desert and a here the point of having three arms is the following.
Piotr Chrusciel: We put an optical switch here which periodically, which is the beam from this arm to that arm so half of the beam always goes to the lower on.
Piotr Chrusciel: And the optical switch makes a periodic switch between these two arms, so what is the gain of doing this well you get a periodic signal and periodic signals.
Piotr Chrusciel: Are can be filtered out from noise so that's the idea of the three on configuration indeed there is quite a bit of Nice here.
Piotr Chrusciel: fiber terminal systematic errors seesmic nice acoustic noise laser noise a dispersion nonlinear effect and so forth, you name it and.
Piotr Chrusciel: If you have a colleague in quantum optics probably add several other things here so to get this kind of accuracy tend to minus five radiance which you think in terms of face is not much and.
Piotr Chrusciel: let's think of two pi together.
Piotr Chrusciel: or apply to you need to buy to get a full destructive interference between to be inside So here we talking about 10 minus five radiance.
Piotr Chrusciel: which corresponds to a.
Piotr Chrusciel: standardization of frequency.
Piotr Chrusciel: Of this order, then this is a bit of a.
Piotr Chrusciel: challenge but well the claim is that this can be done.
Piotr Chrusciel: So.
Piotr Chrusciel: Let me tell you a little more about how this is supposed to work so that's the idea of three arms here, but now, these three arms are mounted on a plate, which can rotate.
Piotr Chrusciel: So therefore by rotating it, you can change the height difference between the beams and therefore measure, the response as a function of the height difference.
Piotr Chrusciel: Now there's a lot of challenges here one of the challenge is a.
Piotr Chrusciel: Nice say same same says make noise isolation.
Piotr Chrusciel: or noise coming from vibrations introduced by moving the system and the collaboration part of the collaboration, who we thought.
Piotr Chrusciel: is going to take take care of this part of the experiment was the analogous not valid, and it was a one of the pillars of the Lego experiments and knows everything about this thing, so we will be using the whole expertise of of Lego for this aspect of the standardization.
Piotr Chrusciel: well.
Piotr Chrusciel: This another group that was supposed to collaborate we hoped we're going to operate on this experiment is group of guys in Russia, because in Russia is in the brown bike metrology Institute, so this is the.
Piotr Chrusciel: End of.
Piotr Chrusciel: The oldest Nada Germany they have the most precise clocks that there are in Germany and therefore probably on us and the idea is that we're going to use this most precise clocks Germany, the information from these clocks sitting in branch bike will be sent to us through a.
Piotr Chrusciel: fiber link.
Piotr Chrusciel: And what's the point of of this.
Piotr Chrusciel: signal from branch side.
Piotr Chrusciel: This is a little bit like.
Piotr Chrusciel: Active.
Piotr Chrusciel: adaptive optics in astrophysics right so.
Piotr Chrusciel: When you look at stars this noise coming from that was here and there is no way.
Piotr Chrusciel: But if you can measure how much noise, there is, you can adapt your.
Piotr Chrusciel: device to subtract this noise to get rid of this month and so that's the idea here, each of these arms, so we have three arms, you know or interferometer and we're going to use the timing coming from Bausch fight to.
Piotr Chrusciel: going to well first is our fiber.
Piotr Chrusciel: optical fibers optical fibers multiplex so you can send simultaneously a lot of various frequencies there so you'll be sending the.
Piotr Chrusciel: Frequency that will be interested in will be.
Piotr Chrusciel: For the detection will be one thing and the frequency stabilizing the arms would be another thing, so this signal coming from these virtual clocks from branch Mike will be measuring how much noise varies at a given moment of time in the fiber.
Piotr Chrusciel: And so, this is done by setting up a another small arm in different metric arm and comparing the signal in the long arm with the very small one, and various something called I think doppler cavities or something like that which can be the news to in real time modify your.
Piotr Chrusciel: The properties of your web guide to get rid of this.
Piotr Chrusciel: Of this noise right so, so this is how this standardization of the arms would have been working here.
Piotr Chrusciel: So what else can I say here.
Piotr Chrusciel: Well, and so that's.
Piotr Chrusciel: Two issues here, so one is to make the whole thing run, we discussed collide, which is enough to think, to start with, and once this is done, the next step would be to select single photons.
Piotr Chrusciel: And to make the experiment with single photons and then it goes even better use various of entangled photons in there.
Piotr Chrusciel: So i'm not going to tell you about single sign on single foreign sources you'd need to.
Piotr Chrusciel: Feed voted for this i'm not going to tell you about single for detection.
Piotr Chrusciel: So that's a story in itself, but let me tell you something about this.
Piotr Chrusciel: difference between what happens in this machine.
Piotr Chrusciel: When you send classical light, as opposed to quantum light so when you're sending classical light in here well and you get.
Piotr Chrusciel: facelifts then love, if you could get a full face if of buyer would just go from seeing something to seeing nothing and that's it I do see.
Piotr Chrusciel: Interference fringes which go dark or or other why we're not going that far is to pay going to tend to minus five rounds, or something like that, but.
Piotr Chrusciel: But that's essentially what happens now, when you're solving sending photons it's a little different.
Piotr Chrusciel: In particular, becomes interesting when you use something called noon states so.
Piotr Chrusciel: This is our mass sender interferometer you sending entangled pairs of photon the machine right, so this is our lower arm, this is our higher arm, this is the detection point now so and you put.
Piotr Chrusciel: So the state which is traveling here is either an photons in the arm a and non in be or.
Piotr Chrusciel: And photons in the arm D and non in the arm a line until.
Piotr Chrusciel: Each of the photons here is coming itself from a product denser production space of integral photons, which means that every individual photon in his own hilarious he speaks up.
Piotr Chrusciel: Face delta Phi when it goes to the machine and because these are product states if you have any photons you're going to get a face, which is not delta Phi but you're going to get n times.
Piotr Chrusciel: So if you manage to control your input noon states, we say n equal to, then, instead of having.
Piotr Chrusciel: Phase shift.
Piotr Chrusciel: Of delta Phi at the output you're going actually do have a face to the other side output if.
Piotr Chrusciel: This year is correct right, so if our understanding of the way that natural equations couple to occur metric is correct.
Piotr Chrusciel: And if quantum fields here is correct, then this is what we should observe and the claim is that well my colleagues here will be able to do something like that, given enough money to to do the experiment.
Piotr Chrusciel: Good so that.
Piotr Chrusciel: Yes, so this is the story about yeah so the.
Piotr Chrusciel: Phase shift actually gets doubled and steady feel very continuously the height, then you get a curve, which actually is double the period yeah.
Piotr Chrusciel: Good so.
Piotr Chrusciel: This and the.
Piotr Chrusciel: Experimental part of this talk and because when you can imagine i'm not sitting in the lab and doing all these manipulations with quantum optics but my part of this experiment was actually to do some calculations, so let me just.
Piotr Chrusciel: show you how how we can how I do this, and for this, let me change.
Piotr Chrusciel: Let me change my screen.
Piotr Chrusciel: This one oh.
Piotr Chrusciel: Good.
Piotr Chrusciel: Yes, so how do we calculate all this.
Piotr Chrusciel: So now.
Piotr Chrusciel: i'm not sure i'm doing each time, by the way, I still have a 15 minutes or something like that what's the standard.
Piotr Chrusciel: Yes, yes, it means okay good, well, I get somewhere so so we're looking optical fibers and.
Piotr Chrusciel: We want to use affordable thanks so.
Piotr Chrusciel: off the shelf high quality optical fibers the non magnetic so they have permeability called new one, and they have a permit Nativity excitement and square.
Piotr Chrusciel: So.
Piotr Chrusciel: The way.
Piotr Chrusciel: They look is following there is a core, which is.
Piotr Chrusciel: made of glass with a certainly certain refractive index say and one is the cladding which has another refractive index and two and one is louder than two that there is a buffer zones attack it, and this is what you have your in your.
Piotr Chrusciel: When your fiber TV comes to your room or fighter fiber.
Piotr Chrusciel: Internet providers.
Piotr Chrusciel: Well, let me call row the radius of the core now the radius of the core is comparable to the optical wavelengths that these links, want to have.
Piotr Chrusciel: Well, once you have means that there is a typical low last window, which you want to exploit and so the radius is comparable to to the optical way wavelengths so.
Piotr Chrusciel: Typical would be five micrometres the cladding will be typically hundred micrometres and, if you want to model, this is actually as good as to assume that discarding goes to infinity.
Piotr Chrusciel: Because the decay of the fields in the cladding is exponential with a characteristic skate like dictated by by the.
Piotr Chrusciel: wavelength, so when you get to the boundary of the cladding your E to minus 20 times the initial signal which is as good to zero, as it gets as far as the experiments are concerned, so, in other words the model is a step index fiber and one here and to hear and.
Piotr Chrusciel: The cladding goes to infinity.
Piotr Chrusciel: So he and b are in a new new which is closed DNA are in a displacement vectors, in other words in other and asymmetric.
Piotr Chrusciel: Data now controversy and answer which satisfies the zero diverted equation, in the absence of charges and currents.
Piotr Chrusciel: And you have the constitutive equations which tell you our F bar in a linear dielectric linear homogeneous electric then that's the relationship where.
Piotr Chrusciel: You is this magnetic constant and this gamma here is something called the optical metric so the optical metric is just a spacetime metric plus a correction involving the.
Piotr Chrusciel: refraction index and the.
Piotr Chrusciel: Rest they for velocity of the medium, so this is your mo is the unit vector.
Piotr Chrusciel: you're describing the rest reign of the medium, and this is called the optical metric or the golden metric, and so the equations you wanted to solve this D F equals zero and divergence of a bar equals zero with this region here.
Piotr Chrusciel: Now the setup we're interested in for the experiment is just a week, possibly turning gravitational field so come a genius at the scale of the lab time independent at the scale of the lab.
Piotr Chrusciel: Was newtonian metric so the mikulski metric and correction, where this is the connector Delta.
Piotr Chrusciel: This way of writing it actually i've learned from from my student.
Piotr Chrusciel: And i've never seen this elsewhere so but that's how you can write it was newtonian.
Piotr Chrusciel: gravitational metric is a chronic a delta and.
Piotr Chrusciel: One on the surface of the US.
Piotr Chrusciel: to five years older than minus nine.
Piotr Chrusciel: And it's gradient is dental minus 16 by meter right if you make this unit less than the gradient wil wheaton minus 16 by meter So if you write down the equations that I showed you in their full glory in this metric you see that terms, involving squares or fi.
Piotr Chrusciel: or derivatives of fi or secondary piece of pie, which will appear there if you just try these two equations and.
Piotr Chrusciel: blow your way through them.
Piotr Chrusciel: Then, then these terms are by seven or more orders of magnitude smaller than the one which on you have fine.
Piotr Chrusciel: So So these are the equations you, you have to solve it, then, if you neglect this all this arrow terms.
Piotr Chrusciel: These are so so these dust.
Piotr Chrusciel: Excellent times, he these are just new times, he within this is raised with the fat metric, the only thing you do to.
Piotr Chrusciel: get to this form, is that these fields are not the fields that you learned in your special relativity cause how you extract them from dispensers, but you have to.
Piotr Chrusciel: feel it to Western definitions so include some metric factors in the definition of this of this fields but, at the end that's the system of equations you get.
Piotr Chrusciel: And, of course, if you're in mikulski space time this is gone and you just get your usual Maxwell equations without any charges.
Piotr Chrusciel: And you say, well, but of course if it's that simple than I don't have to do much work, because I can just reach scale.
Piotr Chrusciel: Time absorb this into time, or in other words absorb this factor this factor is constant we seen your wave guide, so you can absorb this factor in the definition of amiga and use everything you know about wave guides in.
Piotr Chrusciel: In flat bed space time just to get all the effects well this affected is.
Piotr Chrusciel: A warning here, though.
Piotr Chrusciel: If you didn't know that the right equations have a to find a here, but you said, well, let me just take the equations where I don't have these.
Piotr Chrusciel: Five factors here, but they have a time, including here, and I know that a different time.
Piotr Chrusciel: heights time flows differently so I just we scale, the time at different heights and they get the right equations that would be wrong, because if you did that you'll get one minus five here, instead of one minus 259 so somehow.
Abhay Vasant Ashtekar: The way this.
Abhay Vasant Ashtekar: Guy this was a kind of mistake that Einstein first made.
Abhay Vasant Ashtekar: This really.
Piotr Chrusciel: I don't know.
Abhay Vasant Ashtekar: I don't the bending of light, because that is five factor comes in both spatial metric and in the in the time metric and he only took it in the time metric so.
Piotr Chrusciel: Well i'm not aware that he solved the Maxwell equations for he's.
Abhay Vasant Ashtekar: Like, no, no, no, no, no.
Abhay Vasant Ashtekar: Just fighting for the yeah just longing for the Judas and.
Piotr Chrusciel: This is.
Piotr Chrusciel: This is idealize for the same reason that you get a factor of two, namely that the spatial matrix also changes which you have.
Abhay Vasant Ashtekar: absorbed it in the in the calculations absorb it in the in the time time part of you know, because metric as one minus to a more one man is potential times P squared minus D R squared divided by one monster maura so that is what is causing all this.
Piotr Chrusciel: So I know what what you're talking about and I was wondering whether one can actually.
Piotr Chrusciel: pinpoint it as the same mistake it's not clear to me, but it's it's serving the same spirit right Okay, the same spirit that if you do something too fast here you're going to do it wrong so well that's not a big achievement any way to get this factor of two here, but so then.
Piotr Chrusciel: There is some details i'm going to explain your.
Piotr Chrusciel: More precisely what the details, but Silva calculation in mycoskie space timestamp is not calculating this data factor, and if you didn't have this factory here, the result would be beaten proportional to end on.
Piotr Chrusciel: AMI guys the frequency of light to get here and and bar is neither the Fermi to be the.
Piotr Chrusciel: refraction index of the core know the refraction index of the cladding that something which you need to calculate and.
Piotr Chrusciel: that's the end and you get this formula and maybe we'll tell you how we calculate this in a few minutes, back then, you say well just looking at this equation, all you have to do is.
Piotr Chrusciel: Well, the time is down here right, so this is essentially this factor one minus two Pfizer rescaling of frequency, so this is the effect, and if you and that's how you can get this delta Phi formula that I.
Piotr Chrusciel: showed you in my previous slides but.
Abhay Vasant Ashtekar: But the five depends on on space, I mean that was.
Piotr Chrusciel: Like Okay, so now so so, how does this work right so now, so you have these two.
Piotr Chrusciel: two arms of the interferometer and, of course, part of this thing is setting up your local inertial frame in which five zero me second say, well, I adjust my coordinate system or I.
Piotr Chrusciel: calibrate may frequency had the lower part of the arm so maybe you guys done my frequency, but this whole thing is my frequency of your heart of the arm and then I compare it with the.
Piotr Chrusciel: Frequency the higher arm using this formula and then this fight he's actually the difference of potentials between these two ones that's how it works.
Piotr Chrusciel: So the summary of all these calculations, is following you take Maxwell equations in a wave right you ignore five Square, you cannot defy you know Vito five.
Piotr Chrusciel: Both within the wave guide right so of course within the Web guy that's.
Piotr Chrusciel: If it straight.
Piotr Chrusciel: there's no room it's so small that there's no room for violations of rights, but when moving by one meter you also ignore this right, so all these gifts not measurable corrections, one could actually do this estimate indigo.
Piotr Chrusciel: What would be the contribution to this effect well there's something that are they already mentioned well the.
Piotr Chrusciel: Changing the way vector is not the same as getting the phase shift, because the metric between up and down is different, so if you move something here, and this thing is rigid.
Piotr Chrusciel: Then the endpoint will not be have the same coordinate so you have to take this into account so there's an extra.
Piotr Chrusciel: That that's why this formula I showed you at the beginning that the phase shift is length times the difference of pita is wrong, you still have to take into account the difference of geometry.
Piotr Chrusciel: And, and now the other effects, you have to take care of because the radius of the wave guide changes, when you move it to coordinate radius and.
Piotr Chrusciel: And maybe there are some other effects, I mean Dee da so So what are the effects, one is from the cording mine so it's not as straight.
Piotr Chrusciel: Wave like it's a Korean wave guide and therefore.
Piotr Chrusciel: As the photon goes it's still moving in a gravitational field and the story is a say, maybe, if you move the things that one meter apart because will be 30 centimeters or something like that.
Piotr Chrusciel: This could give an effect well the spoiler is that we can be that build a model of coining this produces sideburns in this way right and the amplitude of the sidebar too small too small to be measures, this too is missing in oh actually here.
Piotr Chrusciel: So she'll be calling, you can do the calculation to take into account recording and it wouldn't matter, essentially, what matters is.
Piotr Chrusciel: the height of the Center of this coin now, what about rotation effects, what else is rotating around this access is rotating around the sun.
Piotr Chrusciel: And the spoiler is that the effect of this is larger by three orders of magnitude and the effect we wanted to measure the effect of wanting me to change a fight between the arms is by three orders of magnitude smaller than the rotation of us going to.
Piotr Chrusciel: come to that in a minute.
Piotr Chrusciel: well.
Piotr Chrusciel: If you're over enthusiastic you could think wow maybe I could make a gravitational wave to take you out of bed.
Piotr Chrusciel: And so, so you can calculate all the time, so I try to.
Piotr Chrusciel: I could try to tell you how to calculate this but, all I can just maybe give you the.
Piotr Chrusciel: bottom line yeah, let me just mentioned to you okay so i'm not going to run you through the calculations, but let me just tell you the following.
Piotr Chrusciel: there's a calculation, which leads to these things, and because there's a participation scheme, the effects of the gravitational potential that will be measured by comparing phase between these arms and the effect of rotation of us are additive.
Piotr Chrusciel: So you can calculate them separately, and so what you can do is, as you take rotation think take mikulski spacetime make it rotate and repeat this calculation.
Piotr Chrusciel: That I didn't show you what it is so.
Piotr Chrusciel: One way of doing this is guilt rotating coding, so you get something which is called the bond metric and so.
Piotr Chrusciel: you've solved in a perverted by keep scheme these equations with now this Omega being a rotation victor.
Piotr Chrusciel: and
Piotr Chrusciel: After some work that's what you get.
Piotr Chrusciel: That.
Piotr Chrusciel: The accumulated facelift will be will have this part.
Piotr Chrusciel: Which is coming from the rotation of us so um you guys the frequency of the of light capital me guys the frequency rotation of us, the one over 24 hours.
Piotr Chrusciel: Cisco is, what do you think it is casita is the angle between the plane of your interferometer So if you want to think about this interferometer into her arms here so tita is the angle between the plane of the interferometer and the rotation access so by orienting your.
Piotr Chrusciel: machine in your lab appropriately, you can either get rid of this by making this angle to be zero so you're aligned the plane of your machine with the rotation of the earth so let's in Vienna, would be a summer by somewhere out there.
Piotr Chrusciel: and
Piotr Chrusciel: All you can.
Piotr Chrusciel: So you can make adventure can maximize it or you can vary this angle and actually check whether this formula is correct.
Piotr Chrusciel: So here as they're young close by interferometer that's l times.
Piotr Chrusciel: difference of height it's there.
Piotr Chrusciel: And, and so the gravitational phase shift formula, as I said, is three orders of magnitude smaller than this thing that's the equivalent formula for.
Piotr Chrusciel: One meter displacement between the arms so.
Piotr Chrusciel: Now this several arms machine is a bit expensive and so we're currently trying to get money to build it.
Piotr Chrusciel: But this measuring rotation of using simple photons seems like an interesting and challenging thing first it's actually not trivial to do and.
Piotr Chrusciel: Love think sounds like nonsense, just to ask and tongue entangled photon states to measure the rotation of us, but well why don't we do it if we can and that's what's being built now into that place of my colleagues are right now building.
Piotr Chrusciel: Simple version of this machine which is just designed to.
Piotr Chrusciel: To.
Piotr Chrusciel: measure this effect, first on continuous light and then on single photons and then entangled photons, and this is an experiment which is certainly going to take place, whether this one is going to do it, while it's we missing a couple of million euros, so you.
Piotr Chrusciel: know somebody generous who wants to contribute to taking quantum.
Piotr Chrusciel: field theory in caps facetime and with a few million euros, then we could start.
Piotr Chrusciel: Doing this experiment.
Piotr Chrusciel: last thing I wanted to say that we did the calculation for gravitational waves.
Piotr Chrusciel: Then this has.
Piotr Chrusciel: This is interesting because you could, if it worked, you could have a gravitational wave detector invest up, it would be quite a bit cheaper than.
Piotr Chrusciel: machines like Lego.
Piotr Chrusciel: The most interesting part as i'm concerned is that if you put three detectors on your desktop one looking this way, the second like that, and they said, like that then out of.
Piotr Chrusciel: This machine you're going to get information about what the wave is coming from, without having to ask you, colleagues in, on the other side of the world, just.
Piotr Chrusciel: To try to help you with this.
Piotr Chrusciel: Now, the first proposal of wave guy gravitational wave detector is going back to bragging skin minsky in two papers in 72 and 75 they proposed ring configurations.
Piotr Chrusciel: In with a frequency, which would be in resonance with the frequency of one of the neutron stars and then use this to measure gravitational waves for this, and the idea was dismissed by in this.
Piotr Chrusciel: Historic monumental proposal of Lego bylines is hows and whys and we'd come because of noise and losses now.
Piotr Chrusciel: Meanwhile, we have a lot of progress with optical fibers losses, however, remain.
Piotr Chrusciel: If you wanted to get lygo gravitational wave accuracy, you need a lot of power, and if you put a lot of power in a fiberglass melts the fiberglass or it there is so much scattering that this kills the idea with today's wave guide, so you can do the calculation and but, but you can't.
Piotr Chrusciel: Do a detective today, but while Maybe you can do it in 20 years and therefore it's useful to do the calculation, and this is something that my student Thomas meeting did and.
Piotr Chrusciel: He has a formula for for the face shift and so forth, but I think i'm going to stop here, and maybe take questions if there are any.
Abhay Vasant Ashtekar: So can I ask a question.
yeah.
Abhay Vasant Ashtekar: So.
Abhay Vasant Ashtekar: I mean he's really the fundamental question it says basic question which I got I mean.
Abhay Vasant Ashtekar: I mean you made a big distinction between classical light and quantum light and so on, but all your considerations for electromagnetic waves really classical electromagnetic waves propagating in them in a.
Piotr Chrusciel: bright.
Piotr Chrusciel: And I want you to.
Piotr Chrusciel: This calculations which I didn't show you how to do.
Piotr Chrusciel: You want is them.
Piotr Chrusciel: Using.
Piotr Chrusciel: I would say, vanilla quantization were some clarifications in expansion of the field become operators and and just start with them so.
Abhay Vasant Ashtekar: That that but point is that the the inner part in the photo here but space, I feel like the complex structure that you need to introduce.
Abhay Vasant Ashtekar: That knows about the metric like in the static picture Eric knows about the knowledge, the killing of activity which is really contain in five.
Abhay Vasant Ashtekar: And so, therefore, the norm itself will have the information also fi, and so there will be an additional contribution that comes up.
Abhay Vasant Ashtekar: When you actually look at the interference term because you like to take the photon in the product somehow in all these things on there, and I think that I just wanted to make sure that that was carefully that.
Piotr Chrusciel: No, so this part hasn't been done carefully at so so we did the classical calculations and we're.
Piotr Chrusciel: On started looking where we know the general formula is how these noon States work and stuff like that, but as you're saying you still need to calculate the face and weather.
Abhay Vasant Ashtekar: yeah the fourth.
Abhay Vasant Ashtekar: One article for today yeah so i'll be happy, I mean it's reasonably straightforward so i'll be happy to talk to you in detail if you're interested about how to complete this thing.
Abhay Vasant Ashtekar: Because they may well be I would think that I would be surprised if there isn't some additional factor, because the photon in the product changes.
Abhay Vasant Ashtekar: In the static space time, which is what you're considering appear and precisely by the factor of five and so there'll be some numerical coefficient just like this factor of two five verses five that you talked about.
Abhay Vasant Ashtekar: That they may be something like that in the content, the idea, maybe they've all cancels out, but we should just do it right.
Piotr Chrusciel: right, of course, this is your oven for this gravitational waves, which is certainly a level of classical lightened metric doesn't even have a killing vector here exactly.
Piotr Chrusciel: I don't cause for.
Piotr Chrusciel: Both for this.
Piotr Chrusciel: Even for this rotation effect that would be relevant what you're saying.
Abhay Vasant Ashtekar: Right.
Abhay Vasant Ashtekar: Now, I think, maybe I mean we're to shortlist that Oliver are calculated again.
Piotr Chrusciel: Well i'd be very happy to talk with you about it yeah and and especially with service my students to ISO and Thomas meeting is a.
Piotr Chrusciel: And working on a PhD with me and he's an expert in all these things, and he just we just started looking at the quantum aspects now because we're about to finish the.
Piotr Chrusciel: One one of papers about about these things Center Okay, you know what one of the problems here is a.
Piotr Chrusciel: So.
Piotr Chrusciel: As some of you might suspect I like a mathematical rigor and these kind of calculations, you get this error terms in the equations which you expect our of the order that they show up in the equations, but in fact it's.
Piotr Chrusciel: anybody's guess so now discarding turns into equations and if you don't have some solid mathematical theorems behind it, you don't know whether they're really smaller as they should be, so this is very much kind of mathematical physics, which is a.
Piotr Chrusciel: lot of hand waving which sounds reasonable from a physical point of view, but then I suppose that.
Piotr Chrusciel: i'd love to see these things to be more rigorous than the calculations we've been doing.
Abhay Vasant Ashtekar: I just wanted to say that I really want to express my admiration, because I know that kind of mathematical.
Abhay Vasant Ashtekar: Productivity you do with my family and to go from there to you know worry about coils and rotations and so on, so forth, requires a huge understanding of film logical things I guess appreciation or.
Piotr Chrusciel: Getting, as I said at the beginning, I mean don't spread about the information i'm giving.
Piotr Chrusciel: Experimental talks.
Piotr Chrusciel: My room my reputation will be just down the drain.
Piotr Chrusciel: that's a different.
Piotr Chrusciel: Part of a different one.
Ivan Agullo: I have another question.
Piotr Chrusciel: uh huh.
Ivan Agullo: So pick, thank you for the for the dog, it was very, very clear and very entertaining so.
Ivan Agullo: It was regarding the coin, that you mentioned, because I was thinking about that, and then you mentioned it.
Ivan Agullo: But when you mentioned the coil you were taking into account the fact that light can go up and down when it goes.
Ivan Agullo: But you didn't mention that light is also you know rotating is going around many, many, many times, so you know.
Ivan Agullo: If you won the race frame of the of the libraries, I think the complicated because you know it goes around many, many times and and you didn't mention anything about that is that effect, going to.
Piotr Chrusciel: Okay, so so.
Piotr Chrusciel: that's a very interesting suggestion to see what there is some kind of.
Piotr Chrusciel: Further effects coming from coding and but, so I have one answer would be that this effect will be the same as me makovsky space time, first, to start with, so you have a perturbation of the mikulski space time effects.
Piotr Chrusciel: which must have been studied which and and so, if you move, you have your card here and meet your APP and this effects will be the same.
Piotr Chrusciel: So if you want to compare what happens is these two cards, I think that the level of accuracy of the experiment, the this part of this coding effects will cancel.
Piotr Chrusciel: particles is rotation that you're very justly mentioning we just cancel and the main effect would be coming from.
Piotr Chrusciel: From the one who can create it so if you have a straight wave guide, you can actually right exact explicit solutions of the maximal equation, which correspond to this, if you have a cold, you cannot so you need to make approximation for calculations for this and.
Piotr Chrusciel: Right so so a and then again, the question is how rigorous all this it hurts my heart to say it's not rigorous enough at the level, I would like to have it.
Piotr Chrusciel: At least we had we can make a physically plausible calculation, which shows you what I told you.
Ivan Agullo: Absolutely, thank you.
Abhay Vasant Ashtekar: it's all decide that you want that.
Abhay Vasant Ashtekar: Is it.
Abhay Vasant Ashtekar: Is it possible to do the I mean I is what you're in mind is basically that these photons on, so to say, following a linear combination of the translation and the rotational killing vector.
Piotr Chrusciel: Right now yeah so this I thought about this and.
Piotr Chrusciel: tried with Bobby just to to do things about it but.
Piotr Chrusciel: Just producing an exact solution, which we have these properties.
Piotr Chrusciel: We couldn't right so.
Abhay Vasant Ashtekar: But we will, if we don't produce exact solution is that what physical Is that a correct thing to say that the you should not use the linear combination of these two killing vectors certified positive negative frequency decomposition Is that what you are in mind you want.
Piotr Chrusciel: And now I did I didn't know my baby when sure yeah so so at this stage we starting to understand the quantum theory of a straight way tonight and then we'll be building out their understanding it beyond this first naive.
Piotr Chrusciel: approach that I mentioned.
Abhay Vasant Ashtekar: But, but even Is that what you had in mind, or you had something else in mind.
Ivan Agullo: But I don't know if I would say, a combination of two key factors, because the the rotation is not around you know around the earth or anything like that that will take us around the axis of their.
Abhay Vasant Ashtekar: Of nobody just take it take it mikulski space, the first first approximation that was being said.
Abhay Vasant Ashtekar: I think about dissolving mccaskey space don't don't worry about the earth at all.
Ivan Agullo: Right, but the directory so far from a geodesic that I don't know.
Ivan Agullo: If this combination will will will be exactly what I have in mind.
Ivan Agullo: You know what I mean because you know if you go around a coil you know your thing be far from any type of the USA and and and I think taking that into account is going to be challenging.
Piotr Chrusciel: But the sooner you're thinking about a card which as say half a meter diameter 30 centimeters or something like that well the way guide itself as a core of five micrometres so we talking about the curvature.
Piotr Chrusciel: Going plants around being what six orders, five, six orders of magnitude right.
Piotr Chrusciel: Different, in other words, you need to go 10 to six.
Piotr Chrusciel: Radio to get to do the coding point and that's why even because the space time people just make approximations here and in mccaskey space time does the straight calling produces.
Piotr Chrusciel: Losses so that's the main effect, you get a, in other words, this propagation a vector data gets an imaginary part which is losses, but other than that propagation at this level of approximation is the same.
Piotr Chrusciel: But of course yeah this.
Piotr Chrusciel: idea of having some kind of maybe topology can information from coding is very attractive.
Jorge Pullin: Any other questions.
wolfgang wieland: Maybe a question on the on the modes that are.
wolfgang wieland: propagating along the fibers.
wolfgang wieland: In optical in.
wolfgang wieland: fiber optics phone has also the possibility to generate like higher angular momentum that propagate along the.
wolfgang wieland: Along the fiber so could there be any effects coming from some sort of spin coupling.
Piotr Chrusciel: cell, so this is a one of the steps of the calculation.
Piotr Chrusciel: Where.
Piotr Chrusciel: Some fields are have a quantum rotation number one so, so this is a disease along the way guide and TTS dangle along the way guide, and so this wave as it progresses, as this.
Piotr Chrusciel: rotates along the way pride is low and the mode that.
Piotr Chrusciel: My colleagues.
Piotr Chrusciel: use for the experiments is typically one here and I don't think I remember why it is one, but I it's probably the one which has the the best these losses or something like that in the kind of settings they have in mind so you're using light that rotates in the wave guide as it progresses.
Piotr Chrusciel: i'm not sure if it's this is related to your question, but that's it certainly built in this in these calculations.
Jorge Pullin: Any other questions.
Jorge Pullin: Okay let's Thank you again.
Piotr Chrusciel: Thank you for listening and I hope you do is.
Jorge Pullin: Like listening.