̽��ֱ�� of Cambridge - Adrian Kent

‘ ̽��ֱ��Next Leap Forward’ – four quantum technologies hubs to lead UK’s research drive

Anonymous — Fri, 12 Jul 2019 11:57:52 +0000

̽��ֱ��National Quantum Technologies Programme, which began in 2013, has now entered its second phase of funding, part of which will be a £94 million investment by the UK government, via UK Research and Innovation’s (UKRI) Engineering and Physical Sciences Research Council (EPSRC), in four Quantum Technologies Research Hubs.

̽��ֱ�� ̽��ֱ�� of Cambridge is a partner in the Quantum Communications Hub, led by the ̽��ֱ�� of York, which is pursuing quantum communications at all distance scales, to offer a range of applications and services and the potential for integration with existing infrastructure.

Through these Hubs, the UK’s world-leading quantum technologies research base will continue to drive the development of new technologies through their networks of academic and business partnerships.

“Harnessing the full potential of emerging technologies is vital as we strive to meet our Industrial Strategy ambition to be the most innovative economy in the world,” said Science Minister Chris Skidmore. “Our world-leading universities are pioneering ways to apply quantum technologies that could have serious commercial benefits for UK businesses. That’s why I am delighted to be announcing further investment in Quantum Technology Hubs that will bring academics and innovators together and make this once-futuristic technology applicable to our everyday lives.”

“ ̽��ֱ��UK is leading the field in developing Quantum Technologies and this new investment will help us make the next leap forward in the drive to link discoveries to innovative applications. UKRI is committed to ensuring the best research and researchers are supported in this area,” said Professor Sir Mark Walport, Chief Executive of UKRI.

̽��ֱ��Quantum Communications Hub has already established the UK's first quantum network, the UKQN. They will be extending and enhancing the UKQN, adding function and capability, and introducing new Quantum Key Distribution (QKD) technologies - using quantum light analogous to that used in conventional communications, or using entanglement working towards even longer distance fibre communications.

“We will be extending the UKQN to a national scale, with links over the EPSRC National Dark Fibre Facility to London and Bristol, as well as a link to our industrial partner BT in Adastral Park in Ipswich,” said Professor Richard Penty from the Department of Engineering. “We will be using this network to trial more advanced quantum communications technologies, including quantum repeaters, quantum entanglement, continuous variable QKD and new algorithms.”

Although widely applicable, key-sharing does not provide a solution for all secure communication scenarios. ̽��ֱ��Hub will research other new quantum protocols and the incorporation of QKD into wider security solutions. Professor Adrian Kent from the Department of Applied Mathematics and Theoretical Physics is co-leading this work with other theorists in the Hub.

“We have been devising new applications of quantum communication which allow new secure cryptographic schemes, often also making use of the impossibility of faster-than-light signalling,” said Kent. “We have also been working with experimentalist colleagues in the Hub on the practical implementation of some of these schemes, for example over the UK Quantum Network.

“ ̽��ֱ��next phase of the Hub will allow us to extend our theoretical work and experimental collaborations, including work on space-based implementations via satellite links.”

̽��ֱ��Cambridge researchers will also be working on quantum communications on a chip, particularly for the networking aspects. “One of the barriers for take-up of quantum communications is that the transmitters and receivers are bespoke and made from discrete components,” said Penty. “Integrating many of the functions on the same chip will reduce the costs and speed up commercialisation.”

Given the changing landscape worldwide, it is becoming increasingly important for the UK to establish national capability, both in quantum communication technologies and their key components such as light sources and detectors. ̽��ֱ��Hub has assembled an excellent team to deliver this capability.

Adapted from a UKRI press release.

Technologies that will allow fire crews to see through smoke and dust, computers to solve previously unsolvable computational problems, construction projects to image unmapped voids like old mine workings, and cameras that will let vehicles ‘see’ around corners are just some of the developments already taking place in the UK.

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Ultra-secure form of virtual money proposed

sc604 — Tue, 07 May 2019 23:00:50 +0000

̽��ֱ��theoretical framework, dubbed ‘S-money’, could ensure completely unforgeable and secure authentication, and allow faster and more flexible responses than any existing financial technology, harnessing the combined power of quantum theory and relativity. In fact, it could conceivably make it possible to conduct commerce across the Solar System and beyond, without long time lags, although commerce on a galactic scale is a fanciful notion at this point.

Researchers aim to begin testing its practicality on a smaller, Earth-bound scale later this year. S-money requires very fast computations, but may be feasible with current computing technology. Details are published in the Proceedings of the Royal Society A.

“It’s a slightly different way of thinking about money: instead of something that we hold in our hands or in our bank accounts, money could be thought of as something that you need to get to a certain point in space and time, in response to data that’s coming from lots of other points in space and time,” said Professor Adrian Kent, from Cambridge’s Department of Applied Mathematics and Theoretical Physics, who authored the paper.

̽��ֱ��framework developed by Professor Kent can be thought of as secure virtual tokens generated by communications between various points on a financial network, which respond flexibly to real-time data across the world and ‘materialise’ so that they can be used at the optimal place and time. It allows users to respond to events faster than familiar types of money, both physical and digital, which follow definite paths through space.

̽��ֱ��tokens can be securely traded without delays for cross-checking or verification across the network, while eliminating any risk of double-trading. One way of guaranteeing this uses the power of quantum theory, the physics of the subatomic world that Einstein famously dismissed as “spooky”.

̽��ֱ��user’s privacy is maintained by protocols such as bit commitment, which is a mathematical version of a securely sealed envelope. Data are delivered from party A to party B in a locked state that cannot be changed once sent and can only be revealed when party A provides the key – with security guaranteed, even if either of the parties tries to cheat.

Other researchers have developed theoretical frameworks for ‘quantum’ money, which is based on the strange behaviour of particles at the subatomic scale. While using quantum money for real world transactions may be possible someday, according to Kent, at the moment it is technologically impossible to keep quantum money secure for any appreciable length of time.

“Quantum money, insofar as it’s currently understood, would require long-term storage of quantum states, or quantum memory,” said Kent. “This would require an awful lot of resources, and even if it becomes technologically feasible, it may be incredibly expensive.”

While the S-money system requires large computational overhead, it may be feasible with current computer technology. Later this year, Kent and his colleagues hope to conduct some proof-of-concept testing working with the Quantum Communications Hub, of which the ̽��ֱ�� of Cambridge is a partner institution. They hope to understand how fast S-money can be issued and spent on a network using off-the-shelf technologies.

“We’re trying to understand the practicalities and understand the advantages and disadvantages,” said Kent.

Patent applications for the research have been filed by Cambridge Enterprise, the ̽��ֱ��’s commercialisation arm.

Reference:
Adrian Kent. ‘S-money: virtual tokens for a relativistic economy.’ Proceedings of the Royal Society A (2019). DOI: 10.1098/rspa.2019.0170

A new type of money that allows users to make decisions based on information arriving at different locations and times, and that could also protect against attacks from quantum computers, has been proposed by a researcher at the ̽��ֱ�� of Cambridge.

Instead of something that we hold in our hands or in our bank accounts, money could be thought of as something that you need to get to a certain point in space and time

Adrian Kent

chaitawat

Fiber Optic Cable Blue

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How to cut your lawn for grasshoppers

sc604 — Wed, 22 Nov 2017 00:45:13 +0000

One could be forgiven for wondering what the point of such a question might be. But the solution, proposed by theoretical physicists in the UK and the US, has some intriguing connections to quantum theory, which describes the behaviour of particles at the atomic and sub-atomic scales. Systems based on the principles of quantum theory could lead to a revolution in computing, financial trading, and many other fields.

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge and the ̽��ֱ�� of Massachusetts Amherst, used computational methods inspired by the way metals are strengthened by heating and cooling to solve the problem and find the ‘optimal’ lawn shape for different grasshopper jump distances. Their results are reported in the journal Proceedings of the Royal Society A.

For the mathematically-inclined gardeners out there, the optimal lawn shape changes depending on the distance of the jump. Counter-intuitively, a circular lawn is never optimal, and instead, more complex shapes, from cogwheels to fans to stripes, are best at retaining hypothetical grasshoppers. Interestingly, the shapes bear a resemblance to shapes seen in nature, including the contours of flowers, the patterns in seashells and the stripes on some animals.

“ ̽��ֱ��grasshopper problem is a rather nice one, as it helps us try out techniques for the physics problems we really want to get to,” said paper co-author Professor Adrian Kent, of Cambridge’s Department of Applied Mathematics and Theoretical Physics. Kent’s primary area of research is quantum physics, and his co-author Dr Olga Goulko works in computational physics.

To find the best lawn, Goulko and Kent had to convert the grasshopper problem from a mathematical problem to a physics one, by mapping it to a system of atoms on a grid. They used a technique called simulated annealing, which is inspired by a process of heating and slowly cooling metal to make it less brittle. “ ̽��ֱ��process of annealing essentially forces the metal into a low-energy state, and that’s what makes it less brittle,” said Kent. “ ̽��ֱ��analogue in a theoretical model is you start in a random high-energy state and let the atoms move around until they settle into a low-energy state. We designed a model so that the lower its energy, the greater the chance the grasshopper stays on the lawn. If you get the same answer – in our case, the same shape – consistently, then you’ve probably found the lowest-energy state, which is the optimal lawn shape.”

For different jump distances, the simulated annealing process turned up a variety of shapes, from cogwheels for short jump distances, through to fan shapes for medium jumps, and stripes for longer jumps. “If you asked a pure mathematician, their first guess might be that the optimal shape for a short jump is a disc, but we’ve shown that’s never the case,” said Kent. “Instead we got some weird and wonderful shapes – our simulations gave us a complicated and rich array of structures.”

Goulko and Kent began studying the grasshopper problem to try to better understand the difference between quantum theory and classical physics. When measuring the spin – the intrinsic angular momentum – of two particles on two random axes for particular states, quantum theory predicts you will get opposite answers more often than any classical model allows, but we don’t yet know how big the gap between classical and quantum is in general. “To understand precisely what classical models do allow, and see how much stronger quantum theory is, you need to solve another version of the grasshopper problem, for lawns on a sphere,” said Kent. Having developed and tested their techniques for grasshoppers on a two-dimensional lawn, the authors plan to look at grasshoppers on a sphere in order to better understand the so-called Bell inequalities, which describe the classical-quantum gap.

̽��ֱ��lawn shapes which Goulko and Kent found also echo some shapes found in nature. ̽��ֱ��famous mathematician and code-breaker Alan Turing came up with a theory in 1952 on the origin of patterns in nature, such as spots, stripes and spirals, and the researchers say their work may also help explain the origin of some patterns. “Turing’s theory involves the idea that these patterns arise as solutions to reaction-diffusion equations,” said Kent. “Our results suggest that a rich variety of pattern formation can also arise in systems with essentially fixed-range interactions. It may be worth looking for explanations of this type in contexts where highly regular patterns naturally arise and are not otherwise easily explained.”

Reference:
Olga Goulko and Adrian Kent. ‘ ̽��ֱ��grasshopper problem.’ Proceedings of the Royal Society A (2017). DOI: http://dx.doi.org/10.1098/rspa.2017.0494

Picture a grasshopper landing randomly on a lawn of fixed area. If it then jumps a certain distance in a random direction, what shape should the lawn be to maximise the chance that the grasshopper stays on the lawn after jumping?

̽��ֱ��grasshopper problem is a rather nice one, as it helps us try out techniques for the physics problems we really want to get to.

Adrian Kent

Alvesgaspar

Grasshopper of Acrididae family: Anacridium aegyptium

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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