An interview with a quantum computing scientist

Originally from Iran, computer scientist Elham Kashefi moved to the UK in the year 2000. At the time, she was not very familiar with quantum computing but curiosity got the better of her and she embarked upon a PhD in quantum computing at Imperial College London, in Vlatko Vedral’s quantum optics group. She later undertook a postdoctoral position at the University of Oxford, before moving to the University of Edinburgh. In the early stages of her career, Elham often found herself to be the only computer scientist within her research groups, which were typically made up of physicists, but this worked very much to her advantage, enabling her to find a niche in working as a bridge between computer scientists, experimental physicists and theoretical physicists to develop applications of quantum physics. Elham continued to work across disciplines and in 2007 she established QUISCO, a network that brings together physicists (experimental and theoretical) and computer scientists, in Scotland, to promote interdisciplinary research. In her own words, Elham now ‘works in superposition’, she is Director of Research at Sorbonne University, Paris, and is Professor of Quantum Computing at the University of Edinburgh. The research group she heads up spans Paris and Edinburgh and includes over 20 students (PhD/Masters/Interns) and 5 postdocs (postdoctoral researchers). She is also the co-founder and scientific advisor of French start-up, VeriQloud, which focuses on quantum communication networks. Her fellow co-founders include Josh Nunn, a quantum optics expert in the UK, and Marc Kaplan, a classical cryptographer in France, meaning that again, Elham finds herself as the bridge between two disciplines! Alongside this, Elham is the elected lead for software activities taking place at the Quantum Computing and Simulation Hub (one of the UK’s four Quantum Technology Hubs funded through the UK National Quantum Technologies Programme).

What was it that initially sparked your interest in computer science and, more specifically, what made you specialise in quantum?

When I heard about the early advances in quantum like Grover’s and Shore’s algorithms and spoke to my supervisor, who was a physicist, he explained things to me mathematically. I was very surprised at how mathematics was bringing the two worlds together [computer science and physics]. I am a terrible physicist, I never understood it but when I started listening to the mathematical framework that defines quantum physics, I realised quantum is not just a field for physicists, the mathematics provides the framework for computer scientists too. I felt like I was seeing the beginning of something, it felt completely magical, I had been given the tools to define computation, and it’s hard not to be excited about something like that! I think I was very lucky because my supervisor, Vlatko, was describing things in the language of mathematics, which is a common language, like a bridge between physics, computer science and potential applications and I think the simplicity was very attractive and fascinating for me. People don’t believe me when I say that, as if quantum computing can be simple, but it is the common language of mathematics that helps!

Many people are fascinated and excited by quantum computing, as you said, so why do you think that is?

I’ve noticed that, during my long career, this excitement has changed. Early on, when we did not envision that these technologies would become a reality, it was the fundamentally different way of thinking that excited people. The fact that, for example, in quantum cryptography, key distribution could be based not on a hard problem, as it always had been in encryption, but on the fundamental laws of physics. The fact that we were talking about something in a completely different way and that quantum offered a totally novel way of thinking about computing and information processing was bringing a lot of theoreticians, like myself, into the field. I think the physicists also felt the same, they realized that the fields of quantum information processing and cryptography were taking things that had been studied for 100 years as part of quantum mechanics, that you’d consider to be “bugs”, such as the uncertainty principle, and randomness (that Einstein hated), and suddenly they were making them the feature of technologies and features that could be controlled.

I think over the years, that attraction and fascination has always been there, but now, as these technologies are getting closer and closer, the excitement is about the applications. People are excited that, thanks to quantum, we will be able to change machine learning, resolve the bottleneck we have in drug discovery and we can create a completely different framework for security and privacy, which fascinates me. It is hard not to be excited about this, if you think about how far we have come!

You’ve touched upon this, however, are quantum computers superior to classical computers or just completely different?

They are based on a completely different way of thinking, it is even more fundamental [than classical computing]. Superiority can be defined in so many different ways, but for me, the different way of encoding and processing information is what makes quantum computers very special.

Where do you think quantum computing is at, at the moment, how far off do you think quantum computers are?

I think the roadmap for these technologies is very clear and what has been fascinating is that over the 20 years that I have been in the field, every time a milestone has been set, it has been overcome, so since the start of the field we have not seen a reason as to why something cannot work. We have not seen a reason as to why we cannot have quantum computer, or why we cannot have a quantum internet, or why we cannot have quantum devices, so I think the very fact that there is always this positive way forward means the field will keep progressing, even when progress is slow.

When will I have a quantum computer at home? Nobody knows, and that’s not an issue, the main thing for the field overall is that we keep progressing and every time we progress, we will learn something else. Nobody imagined that quantum imaging would be so important, but we have a Hub [as part of the UK National Quantum Technologies Programme] and this is working with high technology readiness levels. Nobody imagined quantum sensing or quantum RADAR to begin with, likewise nobody imagined the quantum internet would become a reality, but it is happening, so there will be many other applications that we cannot yet imagine.

When do you think quantum technologies will become part of everyday life, do you expect that they will underpin every aspect of our lives or replace current technologies?

I think, in the future, we won’t just have a quantum computer sitting in a corner that can run fast algorithms or a quantum internet that will replace classical internet. I like that you said it’s going to be part of our life, not replace things. Quantum computers won’t replace classical computers, the quantum internet will not replace the classical internet, but it will affect it. With some technologies we are already there, I hope that within my lifetime, and certainly my grandchildren’s lifetime that, for example, they will play a quantum game machine, or something like that and I can say I was a part of it at the start! I’m very confident and optimistic that there will be real, concrete applications of quantum in everyday life soon enough.

People are very excited about the capabilities of quantum technologies, but some people have concerns that, for example, quantum computers could have a negative impact upon the world, particularly when it comes to the potential for a “crypto-apocalypse”. What are your thoughts on this, is it something that people should be concerned about?

That’s a very natural question. In fact, I have been involved in various RRI [Responsible Research and Innovation] activities and what has been so interesting is that quantum has less negative backlash surrounding it than some other technologies. We know that any technology can be used negatively but it seems that, for whatever reason, maybe because it has been such a long time coming, people are excited about quantum. People find quantum to be mystical and know that while they may not understand it, many scientists over 100 years have been working on it. There is this respect that this is a serious scientific endeavor, and people understand that, in the case of security technologies, they can be used for good and for bad and that quantum technologies are disruptive but do provide many opportunities for good.  

What I like about quantum, is that whatever it takes with one hand it gives you with the other, meaning that for every time something is disruptive, there is always a solution. So, for example, you may think if a quantum computer is built, the whole of our cryptographic system is going to collapse and we need to be worried, but immediately, quantum also provides the solution in the form of quantum communications.  

It’s very important that people do critically understand and prepare for the disruptive aspect of quantum sooner rather than later. Maybe quantum computers will arrive in 5, 10 or 50 years but as long as we are ready with cryptographic solutions (such as quantum-safe and classical post-quantum solutions) it will be fine, we just need to be aware of the potential of these technologies early and make sure we are prepared for all aspects of them.  

Could you explain very briefly the concept of ‘blind quantum computation’ and why it is so interesting?

By all means, I’d love to! So, blind quantum computation is a protocol that we have proposed which is essentially about security of the cloud. Right now, everybody is very excited to put all of their data into the cloud, however, security (even of the classical cloud) is very important in order to guarantee privacy. The traditional way you interact with the cloud is by using a secure key, but, what if you want to manipulate your data? Let’s say that you have a database in the cloud where you have uploaded all of your information to, in a secret way, but then you want to search something, you are then faced with a dilemma as to whether you should trust the cloud host and hence give them the key so they can decrypt and run the search for you, or whether you should download the data again and in which case, there was no point in using the cloud in the first place! There is also the issue of integrity, if you are to run a computation in the cloud, how do you know whether the computation is done correctly? The integrity and privacy of the cloud has always been an open question, there are solutions that people have come up with classical encryption schemes called ‘Fully Homomorphic Encryption’ and there’s a solution that I came up with jointly with my collaborators Joe Fitzsimons and Anne Broadbent which is for the quantum cloud. We envision that in future the quantum computer will be accessed via the cloud, in the same way that we have access to the IBM machine at the minute. Let’s say that you want to break an RSA algorithm in one of these remote devices, or you want to do quantum simulation in order to try to find the discovery of drug and immediately, even more importantly, the privacy of your data becomes crucial. Maybe you don’t want to give the remote server access to your work, so the blind quantum computing protocol is a protocol that gives you security of quantum computing in a cloud setting. Our solution gives information security and the possibility of unhackable, secure quantum computing, this is a functionality that cannot be achieved classically.  

We have implemented this protocol experimentally in a proof-of-concept trial and we are expanding it in the Quantum Internet Alliance project in the EU to develop it further. This is, in a way, the vision of my company, VeriQloud, as well, we are looking at various architectures that will enable this protocol to take place and we want to ensure the security of the quantum cloud.

You touched on the fact that you find everything in quantum incredibly exciting but is there one application of quantum technologies that you are most excited to see coming to fruition and being implemented?

For me this is very personal, I’d have to say the security of cloud just because I was involved in the creation of the protocol, I was involved in the architecture design and I am involved in the formation of a company. Another reason I am so excited about this is because it’s very clear that this is something that we cannot hope to fully address using only classical infrastructure and classical encryption. The issue of privacy is something that, as a citizen, I care about because I think data privacy is our right. I know there are a lot of questions surrounding it and so many things have happened where people have lost the trust of the internet and the security and privacy of it, so I think this is a challenge that is comparable to all the other big challenges of our time, like climate change etc. This is something that I understand and I feel like I can contribute to.  

You mentioned that you are split between institutions, and countries, so, is there such a thing as a typical day for you, and if so, what does that entail?

At the minute a typical day is a Zoom day, I guess! My typical day has changed over the years though. During my PhD, my typical day involved talking to many people to understand their languages. Maybe I’m a little bit lazy and could have just read the books, but I was exposed to many different types of people by doing it my way. When I moved into my postdoc positions, I continued this and was trying to talk again with experimentalists, theoreticians and computer scientists and most of my time was spent bridging between them, both technically and physically.

Nowadays, I have a large team between Edinburgh and Paris, including physicists, computer scientists and cryptographers and again, I am bridging between people. I think of myself as an ambassador, continuously making sure people are talking to each other and that they understand one another. In any given day I can talk to end users in industry, hardcore cryptographers, experimentalists, interns and so on. I try to bring the work of all of these people together to see what we can do with the available technologies and people.  

What advice would you give to young people who want to get involved in STEM, particularly quantum physics, and to get to where you are today?

It’s very helpful to be good at mathematics, as I said this, this has been always the common language, even if you’re a physicist, knowing the language of mathematics means you are able to talk to a computer scientist and other people from different disciplines.

Also, if you want to work in quantum, you will be much more successful if you’re open minded rather than being set on working on just one small application. The field of quantum has not yet reached the level that the classical ICT is at where people working on one technology do not need to speak to technologists from different areas very often. Quantum is a big conversation, so whatever background people come from, it’s very important to be open minded and to have made the effort to learn the language of mathematics.

What are your hopes for the future in terms of your work?

I suppose, like any typical theoretician, my hope is that my theoretical work can become integrated and applied. As I said when we discussed quantum blind computation, this is something that cannot be done classically so I’d love to see it being implemented and for our company, VeriQloud, and collaborations to be successful. This vision is that secure cloud computing is actually implemented and integrated [within our communications infrastructure].

More generally for the field of quantum, I’d like to see all of the technologies becoming integrated. I think all of our scientists can contribute to this, so I’m optimistic that it will happen and that one day every household will be able to connect securely via blind computing to a quantum server!

Is there anything else you’d like to add?

Quantum is a very exciting field that is still in development is not one of those fields where everything is done and dusted, it is still expanding and it is very wide in the sense that it touches everything, whatever people are excited about. My belief is that any person who is doing anything to do with the general ICT or physical science and engineering should be touched upon by quantum and should be excited because some aspect of quantum is coming to all of those disciplines. Quantum technology has such a wide spectrum and people will come to realise and appreciate this more and more. Quantum is no longer a subfield, it is a horizontal field that touches everything!

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