Blog

Over the years we have had many distinguished visitors to our Quantum Information and Computing (QuIC) lab at RRI. Lately, with this new edition of the group website, we thought of archiving some snippets of these interactions, as given below.

22nd October 2019: Prof. Artur Ekert

Short Biodata:

Pioneer in the field of quantum communication and quantum computation, Professor of Quantum Physics at Mathematical Institute, Director of Centre for Quantum Technologies, Lee Kong Chian Centennial Professor, National University of Singapore.

A quick chat with him about his views on the various research prospects in quantum information science:

Prof. Sinha: What is the future of quantum computing? I am asking from a dual-hat perspective: one as a researcher in this field and another as a drafting committee member of the National Mission for Quantum Technologies and Applications (NMQTA) in India.
Prof. Ekert: On a humorous note, when journalists ask me, will you see a quantum computer in your lifetime, I always ask them in return, are you referring to the progress in technology or state of my health! The way I see and understand, at the moment there is lots of hype about quantum computing and it has become a fashionable topic. There is Google, IBM, and every single month there are some other announcements of few more qubits. I think the public perception is that this is just around the corner and something will happen. However, people don't realize that if you have 50 qubits or so and they are very noisy. It is difficult to see anything sensible but noise with them in an experiment. We need some breakthrough manipulation technique which can manipulate those qubits with high precision, high fidelity. The parameter space has a number of parameters, there are a number of qubits. There is how they are connected. Can you perform operations on your neighboring qubits? Can you pick up your neighboring system and perform, so that depends. With superconducting qubits you can do it. And you have a situation that ion traps have less qubits but better quality qubits, people in superconducting business have more qubits but they are more noisy. This period of time of 5-10 years will be there with us before we get something better. So, I would say that it will probably be not before 10 but not after 50, i.e. a safe prediction, that we will see a real convincing experiment of the type such as factoring numbers that the classical computer can not crack.
Prof. Sinha: That's a good quote because then we may not be living.
Prof. Ekert: Exactly, I may not be living to be asked this question again. And then what is it good for? Can be answered as with intelligent guessing you can talk about optimization methods, pattern recognition, security aspects and other tasks that challenge a classical computer. Such tasks can be delegated to a quantum processor to optimize certain mathematical expressions. You can even talk about artificial intelligence and machine learning that’s all possible. If you take the progress in classical computer technology. Imagine that you go back to the 19th century, and you talk to Charles Babbage who just came up with an analytical engine and ask what is it good for? The imagination of that guy will not go beyond a very simplistic task that he was interested in at that time. He would say only solving simplistic mechanical tasks such as preparing future mathematical (logarithmic) tables without any errors. Would he ever think about the internet, movies, word-processors, instagram, emails, etc. that we have today? Probably not! So, I believe the future generation will build something very interesting based on the existing tools like simple logic gates which we cannot perceive at the present moment. Twenty, thirty, forty years from now people will be looking at our speculation and think that those guys didn’t know what they were talking about. They could be used for this big thing and that big thing, like Charles Babbage would be thinking in the 19th century. I can make a few intelligent guesses but they will be vacuous from now. At the moment, the present generation will build tools and hand them over to the next generation who will improve those tools and start programming them seriously. In a way we are preparing the ground.
Prof. Sinha: We are preparing the foundations.
Prof. Ekert: We are preparing the foundations, exactly.
Sourav: A related thing to discuss, as you have mentioned, we have the classical computers and quantum computers. We don't know when exactly quantum computers will actually come into practice. So do you think we will have something in transition, something like a bit classical and quantum?
Prof. Ekert: Well, in terms of technology, obviously it is going to be a hybrid. It is not going to be a pure quantum thing that you will put on your desk. Most likely, there are two ways to go. One will be a classical computer that will be connecting to a cloud based quantum computer in early stages. Soon after you will have a quantum processor in your laptop which will be dealing with certain routines that are difficult for classical computation. I don't think it will ever be completely quantum as we may think about it. Such divisions are a little bit artificial. Perhaps you will only observe differences from the interfacing but typically a quantum processor will be embedded in that. So that’s from the technology point of view and that’s how I see it.
Prof. Sinha: Related to quantum cryptography, what is its contextual relevance in current times?
Prof. Ekert: Of course, you know the value of quantum cryptography goes together with the value of the progress in building a quantum computer. Because we do know that quantum computers can certainly break existing classical cryptographic protocols which are based on mathematical operations like hardness of factoring, discrete logarithm, typical cryptosystems RSA algorithm, elliptic curves etc will not be secure anymore. Then, you may ask so then what. So, the answer to then what, is either you are looking into quantum crypto which are immune to quantum attacks or you come up with post-quantum crypto, which means you find mathematical problems that are useful for cryptography like public-key crypto-systems but are immune to quantum attacks. Quantum crypto is good but has limitations. It is ideal for point to point communication, for example you have two clusters of computers, you want to keep them safe, but you also want to synchronise data between them, i.e. say via a quantum channel is just one way of doing it. Quantum crypto has limitations so there will be post quantum. There is a lot of interesting work going on in crypto-community in trying to find those mathematical problems. NSA also now has announced an open call for next generation cryptographic standards that will be immune to quantum attack. It was an worldwide open call. Few proposals were shortlisted and we will know in sometime which will be a preferred winner. But to evaluate the security of such a protocol is extremely difficult. Not only do you have to look at the crypto part that how good and efficient it is, but you also have to understand that we may have a quantum algorithm that will eventually attack those systems. People are talking about using a mathematical problem called a lattice-based crypto. The question is that it will be a mathematical problem of whether it will always resist quantum attacks. Nobody knows. We cannot characterize the power of quantum computers. We only have some conjectures in that direction. So, quantum technologies puts crypto into a very interesting situation. Therefore, we have to work in two directions: (1) develop quantum cryptographic protocols and (2) build mathematical tools to make quantum cryptography resilient to quantum attacks. Both are somehow difficult and they are complementary too. So, one cannot say quantum cryptography will be the only solution. It will be not, since for things like digital signatures, password authentication you may still need to apply some other technique.
Prof. Sinha: Would you agree that quantum cryptography, at least from the experimental point of view, is more mature than quantum computing?
Prof. Ekert: Oh yeah, of course it is much more mature. Quantum cryptographic devices are even commercially available. Quantum cryptosystems can be imagined like a quantum computer having one operation of sending data from A to B. Of course this is much more mature! You can obviously buy quantum cryptosystems today and there are companies that will sell it to you. This said there are different levels of security available in quantum crypto and you may think that the next generation is the device-independent quantum crypto. So it is not to say that there are no challenges in quantum crypto because this device independent requirement would need improvements in the quality of the source and the quality of the detectors. But, it is certainly much nothing compared to the difficulty one would have to face to build a quantum computer.
Prof. Sinha: What are the interesting problems in the fundamental aspects of quantum information we should be looking at? We have just discussed quantum computing and crypto but we have both fundamental science and technology.
Prof. Ekert: The impact of quantum information science goes beyond practical applications. Certainly it just revises our notion of computation that it is not just a mathematical thing and people realize that the theory of computation is really a part of physics rather than a part of mathematics, because what can be computed depends on the underlying physics. When you discover something new then you can use the process that you discovered for the purpose of computation. It means that you can create a new set of logical operations and therefore a new set of instructions which in this case are not having classical counterparts. So, I think that exploring the fundamentals of quantum information, may get us more insights into the theory of computation. There are people in more areas of physics or, if you want to call that physics, something like String theory for example there is a lot of interest in the community of quantum gravity to see, for example, how entanglement can underline certain features of space-time. I think those connections which now are being made between the foundations of quantum information science, foundations of physics and foundational understanding of complex systems; and all those links that people are trying to explore with relativity, are aspects that quantum information science has brought into the community. So, in my view it is much more significant than just the progress in information technology in having this deep understanding of reality. To be honest, my perspective is that when it comes to building a quantum computer, my preferred scenario that I would love to see happen, is that this quantum computer cannot be built for a good reason. Right now we know it is difficult to be built, however understanding is that there is nothing in physics which prevents us from building a quantum computer. We have limits towards achieving precision in quantum fault-tolerance and quantum error-correction; to which we also have answers to. It is more a question of getting technology upto a certain degree of precision and then scale it up. But there is no fundamental reason to be able to build a quantum computer. However, if it is discovered that the quantum computer cannot be built then this would be the best case scenario. As then the physicists would be jumping up and down, and you would learn something more profound about nature.
Prof. Sinha: What about the funding agencies, then?
Prof. Ekert: Actually, then you can promise them something even more powerful computers. You incorporate this new phenomena. Like if you move from classical to quantum, you build a quantum computer as more powerful. Suppose you discover something in quantum, call it post quantum or something else - after quantum.
Prof. Sinha: Beyond quantum.
Prof. Ekert: Prof. Ekert: Yaa, beyond quantum theory, thank you! So you have something like "beyond quantum theory", that excludes the building of a quantum computer. So you allow a proper understanding of the phenomena that can help you develop an even more powerful device. Then you can go to the funding agency and say, “forget about quantum computers”, it's now passé. Now we are building BQC (beyond quantum computers) and they would be like wow! So in other words, this would constitute the progress in Physics and that will be the best outcome. However, while building quantum computers we may face contradictions as building quantum computers will be building the most sophisticated device ever built by mankind, right? Although nature has built even more interesting beings. This will actually push the boundaries of playing with quantum physics. This is the biggest challenge and I am glad that this has really come up since otherwise the funding agency would not have invested so much money, allowing you to test the foundations of the subject. And here you have such a perfect excuse of building a valid quantum computer. But for a physicist this would be building a very complex multiparticle quantum interference experiment. There is nothing more complex made by people on this planet. This for me constitutes the online process of testing the quantum theories to its limits.
Prof. Sinha: What do you think a national mission should concentrate on? Not building a quantum computer or building one, or other things as well?
Prof. Ekert: So, you can call it a BQC mission. I like that way: beyond quantum. I think that the mission should boldly go where no one has gone before; while promising the practicalities with modesty. Concentrate on the development of quantum crypto devices, simulators, repeaters, memories, quantum computers for pattern recognition or may be for crypto purposes at some point. However while doing so at every single step when you make the system more complex and every time you check where it can go wrong. Everytime it goes wrong, you feel happier that bingo! Now we are moving to ‘BQC’.
Prof. Sinha: You better credit me for this term.
Prof. Ekert: I just made a statement now officially that I do not claim the ownership of the term.
Sourav: Beyond quantum.
Prof. Sinha: You know Jonathan Dowling keeps complaining that people do not give him credit for the quantum age thing for there being the second quantum revolution. Apparently he coined that. So he wants a citation everytime that happens. I think I am safe.
Sourav: It is recorded also.
Prof. Ekert: Yes, it is recorded and we have a witness here. I would personally mention your name when I write BQC: beyond quantum computing.
Prof. Sinha: I would still like funding for the quantum stuff for now and hope for the beyond quantum.
Prof. Ekert: So position yourself. You can take in your portfolio, I work for QC but I position myself BQC.
Prof. Sinha: So I am there for the foreseeable future. With that then, what is the impression from your visit about our lab activities, our stuff at RRI?
Prof. Ekert: Usually, it is customary to say good words, but I think I didn’t expect this to start with my first visit. As from my previous visits to other places in India, I didn’t see any experimental groups in this field, and your’s is exceptional. It may not sound impressive if I say it is like any other group anywhere else but I usually visit groups that are very good, so that itself means a lot. Going to your lab it could be anywhere in Oxford, Cambridge, MIT, Singapore, etc. Although the optical tables all around the world look pretty isomorphic with those experiments, when you speak to the guys, you immediately see how they present something, how they go to the essential details, they are pretty confident and proud about what they are doing and also are having fun. In that note, I think you have one of the best labs!
Prof. Sinha: Thank you very much and of course we should thank him also so that it is on the records.

Podcast:

15th March 2022: Aluminum Jubilee of QuIC Lab

Messages and wishes from our past members of the QuIC lab:

Ashutosh Singh: Dear Ma'am,This is truly music to my ears that we are celebrating the 10th anniversary of the QuIC lab. Time flies, but not memories! Congratulations to all the current and previous lab members and especially you as PI of the QuIC lab which has achieved several feats in all these years and has established itself as one of the preeminent labs in photonic QIP. My journey at RRI and QuIC lab as a Ph.D. student has been truly amazing that has contributed significantly to my career growth. I wish you all the very best in your endeavors and great success in your careers. May you all achieve the sweetest dream of your life, and fulfill your aspirations.Wish you all the best.
Prof. Sinha: Thank you very much.
Kaushik Joarder:Respected Madam,Congratulations to you and all the past and existing lab members for achieving this milestone. I feel proud to be a part of QuIC lab, which has been one of the leading research facilities working in the field of 'anything quantum'. I feel privileged to be able to work on various exciting quantum experiments during my Ph.D. tenure. I also cherish the memories with all my labmates, who are both exceptional scientists and extraordinary friends. I heartily wish for the success and growth of this lab. May the force be with you.
Prof. Sinha: Thank you for the wishes.
G. Rengaraj:Dear Ma'am,Many thanks for your invitation and it's my pleasure. I want to add the following lines: "The RRI - QuiC research environment and consequent interactions with my peers and advisor provided me with a toolbox of different skills that has paid dividends in my research career and professional relationships." QuIC lab,I truly wish all my best wishes and love,and thank you so much for getting the opportunity to be a part of it.
Prof. Sinha: Thank you very much.
Debadrita Ghosh: QUIC lab: the name which is always very close to my heart. This is partly because when I first saw her she was just born and then I experienced her day by day while she was growing! But mostly because, it gave me the opportunity to learn new things, to face unseen challenges, to acquire the knowledge of both optics and quantum mechanics, to work in a group, to be patient, to not to lose hope, to celebrate the success! And how time flies. Today, 10 years have passed! I am really happy that I get this opportunity to convey my feelings. It is really hard for me to say something which is coated with my deep emotions and sentiment. I adore the name, the logo and, the theme of research, the place and overall the group. Though I am physically away, I still feel that I am part of this lab and its initiatives. This is because I met some of the people at this lab whom I am still in touch today and I know they are always there when I need them. I still remember those days when we used to level the cupboard, organize the stuff we purchased, and learnt how to deal with the Ti-Saph laser. Oh, yes I love that laser! I can see that day when we first saw the single photons, succeeded in coupling photons into the fibre and observed the coincidence peak. It is not like there were always happy days. Days passed when we did not achieve the Hong-Ou-Mandel dip and then one evening, I still cherish that moment, we observed the famous dip! I know, it seems so obvious now to observe those. But, on that optical table of the QUIC lab, when I first observed those, that instant was not any less than an eureka moment! We also spent quite a few days seeing the threeslit pattern with single photons. I remember asking Ashutosh, ’count mila?’ and he is, with his sad face ‘knahaa count !’ But finally, he finished the experiment with great results. And ma’am was there, always, while building it up with all her efforts, providing us all the resources we needed, and giving us the care and support when we needed that most. I truly admire the spirit that has been maintained that it was never about ‘I’ but about ‘We’, be it a moment of failure or success. I confess that I really miss that ‘We’ and will always do so. There were tea breaks, there were Pizza parties, there were birthdays with cake, there were enthusiastic visitors, there were conferences and yes, food, there were new experiments, there were challenges and thrills, there was despair and then there was also hope and joy. I really wish I could taste all those flavours once more. QUIC lab, I truly wish all my best wishes and love. And thank you so much for getting the opportunity to be a part of it...
Prof. Sinha: Thank you for your wishes.