Towards Practical Quantum Technologies

Lead Research Organisation: University of York
Department Name: Mathematics

Abstract

In order to make online purchases, we need to send our credit card details to the merchant, and the importance of doing so secretly is clear. Remarkably, there are known ways to break the schemes we use today. Fortunately, we don't today have the technology to perform these hacks quickly enough for them to be useful in most applications. Nevertheless, there are several reasons to be uncomfortable about the present schemes. For one, there are some secrets for which it might be worth investing the large amount of time required to hack, and hence that we would like to encrypt more securely. Secondly, we expect that one day we will have technology powerful enough to quickly break the current schemes and so it is important to be ready with a new paradigm.

Quantum technology is a promising candidate for this. It has the advantage that its security doesn't rely on hacking taking time: instead it can be proven that the scheme cannot be broken, provided the equipment used for the protocol works as it should. However, building such equipment is very challenging because these schemes rely on the use of extremely small systems, which are hence difficult to address and highly susceptible to noise. Many experimental groups are striving to achieve new levels of precision and protection against this noise.

In the case of another important task, random number generation, quantum technology can have an arguably more significant effect. Random numbers are useful in numerous applications from simulations to gambling, and in such applications use of classical pseudo-random numbers (which contain subtle correlations) could be detrimental. A shrewd gambler who found a way to exploit these subtle patterns could in principle bring down a casino, for example. Unlike any classical algorithm, a quantum random number generator can certify the generation of true randomness based on the laws of physics, and hence provide a guarantee to users that no subtle correlations remain.

The research in this proposal constitutes work that will directly underpin such technologies, informing the most promising ways to take them forward, and investigating other ways in which quantum theory can be of use in cryptography. It will also enhance our understanding of the foundations of quantum theory, giving a fresh take on what Einstein once called "Spooky action at a distance".

This research would be undertaken at the University of York and will involve collaboration with international project partners in Michigan, USA.

Planned Impact

Work area I aims to deliver new protocols for device-independent tasks that are tuned so as to be as easy to implement as possible. This has potential for impact in the following areas:

-- applied sciences/engineering/companies manufacturing cryptographic equipment: the ideas contained in this research may set the agenda for these groups, striving to build devices with the properties needed to implement the cryptographic schemes and eventually market them.

-- government organizations: as they adapt current methods to situations where cryptographic security is important.

-- policy-makers: exposing the boundaries of what is possible will enable informed decisions to be made about future cryptographic standards, and what we should aim towards.

-- general public: in the longer term (perhaps 20 years or so), new cryptographic technologies will reach people's homes, and they may one day use software and hardware implementing protocols that build on those developed in this proposal.

-- in gambling applications where use of random number generators that provide certification can protect the casino from certain attacks.

-- branches of science that use random numbers to do simulations (e.g. climate sciences, financial mathematics, computational physics) will benefit by having a stronger guarantee that no subtle correlations were present that could have silently affected the results (as would be the case with a pseudo-random number generator).


Work Area II will find new information processing tasks that single out quantum theory and hence help us understand this fundamental theory from a new perspective. The wider impact of this is:

-- quantum mechanics is one of the most fundamental theories of physics and finding new ways to understand and appreciate what makes it special benefits physics as a discipline

-- history suggests that new fundamental relations eventually lead to technological applications, and, although at this stage it is difficult to make concrete predictions, the most likely candidates are for information-processing protocols.


Both work areas will generate new knowledge which will impact

-- students: through bringing research ideas into courses and summer school presentations

-- the general public: new ideas for quantum technologies are gradually permeating the minds of the general public.

Publications

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M. Weilenmann (2017) Analysing causal structures with entropy in Proceedings of the Royal Society A

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Miller C (2018) Keyring models: An approach to steerability in Journal of Mathematical Physics

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Vilasini V (2019) Analyzing causal structures using Tsallis entropies in Physical Review A

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Cope T (2019) Bell inequalities from no-signaling distributions in Physical Review A

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Pirandola S (2020) Advances in quantum cryptography in Advances in Optics and Photonics

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Brown P (2020) A Framework for Quantum-Secure Device-Independent Randomness Expansion in IEEE Transactions on Information Theory

 
Description There were two main directions that this project took. The first was underpinning work for future quantum technologies. In this regard we investigated new protocols whose aim is to make it easier to perform a new-type of cryptographic protocols, termed device-independent, which aim to provide even stronger levels of security to users. Our first line of investigation was whether use of other Bell inequalities (which are a crucial ingredient for device-independence) could enable lower quality detectors to be used (quality of detectors is a key bottleneck). In spite of finding numerous new Bell inequalities, extending what is known on the subject and developing some algorithms for these, our new Bell inequalities turned out not to be promising in practical situations due to other implementation difficulties. We instead focused on development of a technique for analysing new device-independent protocols. While previous techniques were tailored to essentially one protocol, our technique can be applied to a wide range. We used it to analyse new protocols that have faster generation rates. This enabled the first experimental demonstration of device-independent randomness expansion, a milestone for the field, through a new collaboration with a group in Shanghai, China.

In the second direction of this project we pursued the underlying theory of causal structures with a view to thinking about causal explanations of quantum correlations and those in other generalized probabilistic theories. We found a new technique based on measurement entropy that allows us to analyse causal structures in more general theories and identified some minimal requirements of any correlations that arise from any reasonable notion of causation within such structures. Furthermore we have introduced a new task, self-testing of physical theories, and how to apply it to quantum mechanics. We put forward a candidate task for self-testing of quantum theory and investigated it within a framework of theories, showing that quantum theory performs better than many within the set. Further research is required to decide optimality amongst all other theories, but, if confirmed, this would lead to a new more direct experimental test of quantum mechanics.
Exploitation Route New understanding of causation in quantum mechanics helps to inform others looking for new physical theories (in particular trying to unite quantum mechanics and relativity theory).

We hope that our certificates of non-classicality will make it easier to build device-independent quantum technologies as will our new framework and software for analysing device-independent protocols. We have teamed up with an experimental group for a first demonstration, but we expect further work to follow in this direction, hopefully looking at new protocols if we can further tighten the theoretical analysis to yield further improvements to the rate.
Sectors Digital/Communication/Information Technologies (including Software),Education,Manufacturing, including Industrial Biotechology,Security and Diplomacy

 
Description We have been in discussion with the company Cambridge Quantum Computing about ways to exploit device-independence for QRNGs. We have further engaged with a focus group of the ITU-T Focus Group on Quantum Information Technology for Networks (FG-QIT4N) where I gave a tutorial last year and provided input to some of the proposals. On the back of the work in this grant together with the National Physical Laboratory and several industrial partners we have leveraged new funding from Innovate UK to analyse commercial quantum random number generators and takes steps towards an assurance process for them.
Sector Digital/Communication/Information Technologies (including Software),Security and Diplomacy
Impact Types Policy & public services

 
Description The EPSRC Quantum Communications Hub
Amount £23,961,861 (GBP)
Funding ID EP/T001011/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 12/2019 
End 11/2024
 
Description Michigan 
Organisation University of Michigan
Country United States 
Sector Academic/University 
PI Contribution We worked together on a joint paper, contributing several ideas, working on the numerics and theoretical parts.
Collaborator Contribution We worked together on a joint paper, they contributing several ideas and theoretical parts.
Impact The paper Keyring models: An approach to steerability, Journal Of Mathematical Physics 59, 022103 (2018)
Start Year 2017
 
Description USTC 
Organisation University of Science and Technology of China USTC
Country China 
Sector Academic/University 
PI Contribution Our research team provided theory behind device-independent randomness expansion.
Collaborator Contribution The team in China performed the experiment that demonstrated device-independent randomness expansion for the first time.
Impact So far we have a preprint: https://arxiv.org/abs/1912.11159
Start Year 2018
 
Description Analysing causal structures in generalised probabilistic theories 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk at a ``Mini-Workshop on the foundations of quantum mechanics''.
Year(s) Of Engagement Activity 2018
 
Description Device-independent quantum random number generation -- extending the proofs to new protocols 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Seminar during a collaborative visit to Shanghai. Following the talk we discussed new potential future collaborative projects.
Year(s) Of Engagement Activity 2019
 
Description Discussion of assumptions behind two arguments for the reality of the wave function 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk at a workshop that led to discussions afterwards
Year(s) Of Engagement Activity 2019
 
Description Frontiers of Quantum Information Physics 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a talk at this workshop at the Kavli Insitute, Santa Barbara, USA. This resulted in significant discussions after the talk.
Year(s) Of Engagement Activity 2017
URL http://online.kitp.ucsb.edu/online/qinfo_c17/
 
Description Generating Random Numbers with Untrusted Devices 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk at a conference, led to further discussions
Year(s) Of Engagement Activity 2019
URL https://sites.google.com/york.ac.uk/cybersec/workshop-june-2019
 
Description Heriot-Watt Physics Colloquium 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact I gave a colloquium for the physics department at Heriot-Watt University, which sparked questions and discussion afterwards.
Year(s) Of Engagement Activity 2017
URL https://projects.eps.hw.ac.uk/seminars/seminars/ipaqs/archive?page=6
 
Description MIQC2 Symposium 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Symposium was part of a satellite meeting of QCrypt 2017. I gave a presentation and took part in a Q&A session with the other speakers afterwards.
Year(s) Of Engagement Activity 2017
URL http://empir.npl.co.uk/miqc2/2017/09/15/symposium-assurance-and-certification-of-quantum-communicati...
 
Description Outreach activity, Manchester 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Workshop for a Women in Mathematics Research Event aimed at A-level students.
Year(s) Of Engagement Activity 2018
 
Description Outreach activity, Sunderland 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Running stall at a fair for A-level students at a College in Sunderland
Year(s) Of Engagement Activity 2018
 
Description Outreach activity, York 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Workshop for students aged 13 to 14 at the University of York.
Year(s) Of Engagement Activity 2018
 
Description Presentation at Quantum Information, Computing and Control summer school 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact I gave a series of tutorial lectures at a summer school for PhD students and took part in subsequent discussions of the topics.
Year(s) Of Engagement Activity 2018
 
Description Smooth-entropies in Axiomatic Thermodynamics 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This was a talk about research conducted during this award and helped make it better known to the community.
Year(s) Of Engagement Activity 2018
 
Description Smooth-entropies in Axiomatic Thermodynamics, Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Talk about research conducted during this award and helped make it better known to the community.
Year(s) Of Engagement Activity 2018