12.05.2024

Good afternoon ladies and gentlemen and. thank you for the kind introduction this. is daji fukuda from National Institute. of advanced Science and Technology where. I serve as a prime senior researcher. so it is a great honor to be able to. present at q2b 2023 thank you very much. for the opportunity and I'd like to. express my gratitude to the organizers I. know it will be a tough job to organize. all of that but we appreciate your. efforts so today I'd like to discuss the. quantum Optical sensing and Metrology. for Quantum Optics at our Institute. which is called iced we are using a. semiconducting to use a single photon. detection and we are involved in. research and development as well as. application and we are also developing a. test bed we are also trying to make sure. that the Metrology is right so as to.

Help develop the use of quantum. Technologies. and Quantum sensing in particular. actually this morning in the governing. session my colleague Dr horiber made a. presentation. and this is a little duplicative of that. so our Institute is to establish a new. organization by the end of this month. it is. titled Global research and development. hub for business by Quantum AI. technology or gquot for short and so we. will provide a location for research and. development of quantum devices and. provide prototyping services and we. intend to become the international hub. for industrial applications of quantum. Technologies so we have the fabrication. facility we have the clean room for. semicon for superconducting we will also. have a design Fab for superconductor. super conduction and silicons and allow. for a large system Quantum devices to be.

Built there. and so that will lead to new uh Quantum. devices and that could become. combined or combined or used in tandem. with computers both quantum computers. and IAI as well so that it can be. brought to Youth for Logistics drug. Discovery material design communication. energy among others. and so we are actually looking at. various use cases we hope that there. will be new use cases that no one will. imagine today. so if any of you are interested or you. have any ideas please come to me or my. colleagues and we will be delighted to. discuss all that so uh basically we are. working. um using the quantum anneliers and. quantum computers that would be the. first Quantum devices to to come but we. are also focusing on Optics using light. and I'm the Optics guy so I'd like to. particularly talk about activities in.

That regard. so first our strategy at ice for. development of quantum sensing as you. can see these are the three pillars of. our r d. one is the core technology. and then we have application and test. bed and the third pillar is Metrology so. the core technology is about a Quantum. Optical sensing what specific technology. to develop and when it comes to a. Quantum sensing as a doctor tatano. disgusting you could use diamonds but we. are particularly focusing on light and. Optics and really a Precision. measurement of those photons so. nonclassical and Quantum states to we. want to measure that which means that. the classical. measurement instruments are not are no. longer relevant we really need very high. performance. for example the detection efficiency we. would need near 100 percent. and so we will need a very high speed.

And we also need to be able to detect. photons. as of now what technologies are out. there we only have one solution which is. using super conduction but then Super. conduction is usually associated with. cryogenic Cooling and that will need. some expertise and you will need the. acryogenic coolers which are expensive. but. um if we are to focus on the optical. Quantum sensing. we want it to be easily or readily. usable but currently we have a high. threshold and we believe ice can. actually serve a role there to lower. that barrier or entry barrier so we are. trying to look at development and the. fabrication of the sensors and we also. want to present to what applications are. possible and gather host a gathering of. interested people so that the quantum. based Technologies are more readily. usable widely. and for those Quantum devices to be used.

Widely on a business scale they will be. various components and performance. requirements and the question would be. how to ensure that the performance is. what it claims to be and at that stage. Metrology will become relevant. for example if you have the encoded. Communication in crypto communication. you would need to know the number of. photons to begin with otherwise you. won't be able to ensure security of that. communication. so the amount of light meaning the. photon count needs to be measured and. that requires a very high level and. sophisticated level of Metrology so that. the use of a Quantum Optics can develop. in a healthy and steady manner. so I'd like to refer to some cases so. first on Quantum Optical sensing. at this point in time the um let's look. at what Optical Computing uses we have. some results of some groups within ice.

Then I'm just showing part of that so. they can be largely classified into. gaussian boson sampling and fault. tolerant quantum computer with photonics. so with regard to both on sampling. are among the leading part players there. in that field. and so this is one part of a Quantum. Computing and it is really geared to a. particular type of computing such as a. combination. Etc and they are capable of solving. those particular questions at very high. speed and we understand that at 4 50. um. a quantum number of 50 uh they have. already demonstrated their effectiveness. on the other hide the fault tolerant. quantum computer with photonics this is. quite challenging we don't really have a. real system available yet but there are. some uh players as you can see on the. slide and uh various um ideas are coming. out. so what's common among those.

Architecture is here in the lower half. so we have some Quantum Light Source and. we also create this stay State and then. put it into a programmable State and. then you will get an output and detect. that and that would be the result of the. computation. and in that process the issue is because. light is a boson the quantum state is on. overlapped and so we will need to. understand the number of photons that. will Define the quantum state. and so determining that is a big. challenge. so ordinary detectors like APD for. semiconductors you can't actually count. the number of photons. and so for these computers or for good. opposal sampling one big challenge is to. have a very high performance Photon. detector. so what we are doing here is we are. using super conduction. and I'm sure anyone here would. understand what super conduction is and.

So it's about Metal resistance dropping. to zero ohm at a certain critical. temperature so there's this drastic. transition happening and we are using. this transition to detect the photons. so we're using the uh transition and so. that's why we call this Tes a transition. Edge sensor so the Tes depends on the. incident energy of the photons. and so this is what we've developed at. iced it's a photograph so each block is. a sensor. and we have the optical fibers. connecting them so the important thing. is about the incident. Photon State and how. you can detect that very faithfully and. you will mean that the Loft needs to be. small or the detection efficiency needs. to be very high. and to realize that we are using a. particular of the cavity so that the. light can be absorbed as much as. possible. or here we're looking at this high.

Efficiency connection of optic fibers. and so now we have actually realized and. detection efficiency of above 98 percent. so here we have the coherent light and. measurement of that so with a coherent. light they are discretized and you can. see what the waveforms look like and you. can see the discrete levels and so for. each wave height the distribution is. shown in the lower part which actually. reflects the. Quantum State and so the height of the. signal can actually directly convert it. into the number of photons. so we have these unique features um of. of this um Photon detectors and I'd like. to talk about two cases of application. one is about using the quantum. information so we talked about this. Photon photonic quantum computer and. that can use this technology. and to realize that one important thing.

Is that this if for any calculation we. will need to have four linear. Transformations and one nonlinear. transformation those five in total this. is known so those are phase shifts. displacement squeezing beam splitting. those are the four linear. Transformations and then. squeezing. I need some water more of technological. development but those four are already. available in one form or another so. um those are very ready for um Optical. computers but the challenge is really. the nonlinear part which is called the. cpg the cubic phase gate and this needs. to be realized and uh for uh real. photonic computer so we have two uh. qubits but you have a great but then in. the case of light the coherent time is. long but each Photon has very small. nonlinear part and therefore the cpg is. very difficult to develop and we want to.

Resolve that Talent. and so for the cubic phase gate there. are a number of protocols that are. already proposed and we are. thinking about a special stator which is. very nonclassical and we are using we. are cooperating with University of Tokyo. and NTT to develop that and so this. shows what we are doing so NTT has a. very high pressure high quality. foreign. crystals that we can use and then we. will use that and send it to our Photon. detectors for detection and then we will. use a homodyne detector to measure the. generated States. so here suppose our subtract and photons. that will mean the remainder is less. nine photons and so we will need to look. at what happens after that those end. photons are subtracted and this is what. you get so the upper part is the. experiments and ends is the number of. subtracted photons and the bottom part.

Bottom panel shows simulations so n. equals zero is the same so the squid. light it comes out as is and you can see. there's a kind of ellipse and so. according to the heidenberg's. uncertainty principle and this adds a. little squeeze and so some noise on this. direction and less noise in this. direction. but the point is uh at any cross section. it is a gaussian distribution so it's. only linear operation that's you can do. so that's the limitation as long as. you're using squid light but then if we. have one Photon subtracted you can see. there's more Distribution on both sides. and if you look at the cross section. this is non gaussian. and so we can use a nongaussian state. and so uh this is like the schradinger's. cat situation. and so this is very nonclassical. further. in the middle here. and we see this dent and we have this.

Negative figure. and the negative figure is not possible. according to classical. physics so you know this is like the. probability going into negative. territory so it shows how nonlinear we. are getting. and then this is actually without a. lawth correction and so this is actually. the first um of its kind in the world. and so we are really uh working hard so. that we can realize it's a cubic phase. gate and further on go to developing a. real uh quantum computer now the second. case. and this is about application for Life. Sciences. and so on a salt feed different tone. so we have some dyed cells and we apply. some laser lighter then they will be. very weak fluorescence coming out and. the wavelength. um so can tell us about what reactions. are happening inside the cells or what. uh functions are related to that.

Particular part and so this is about. getting to know more about what's. happening inside the cells and that. should lead to important understandings. about the mechanism of life and so we're. trying to use this technology. so here we have this cell from the vein. of a cow and so. blue is a nuclear and then we have the. mitochondrial. Etc so different colors indicate. different parts. and so this is just one example. successful one the important point is. that we're only using a very weak Power. of One micro Watt. usually 100 micro watt or that level of. power was unnecessary but because of a. Quantum sensing we can actually use a. much weaker light to get the same. information so you know if you have a. cells in a colony and suppose you have. one some normal cells but some aberrant. cells as well or maybe one cell is.

Actually producing an industrially. usable and useful material but others. are not it's it may lead to us being. able to discern that very easily. and clearly. so the thing the important thing the. thing is we can actually or we may be. able to observe those cells inside you. and we are working with the scuba. University under a Consortium to develop. this line of application and again this. is really about bringing Quantum sensing. to everyone. final topic is about Metrology. as well. so this is really creating or providing. the foundation of the use of a Quantum. and Optics and Quantum devices and so we. are trying to provide a standard or. reference for a single Photon radiometry. and so this is really about developing a. national standard for traceable. performance testing of optical devices. so that. we can have a reliable.

Detection efficiency devices becoming. available for people and obviously if. there's a company developing and. marketing that that can actually be a. seal of approval we are also trying to. um. provide reliable detection efficiency. evaluation various components would be. necessary and those each in every one of. those components need to be evaluated in. a reliable way that's the same for. everything. so it's about any Optical or Quantum. device and make sure that the. performance standards are there so a. qedc emnq there are a number of. gatherings that are working on that and. is working with those initiatives and we. are also trying to make sure that the. measurement validation is happening and. there is harmonization across that. borders and so we are referring to the. international developments and making. sure that there is an international.

standard so that the certification is. valid anywhere on this planet. so that was about the three activities. at ice the National Institute of. advanced Science and Technology thank. you very much