Towards Practical Quantum Technologies

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.

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.