Relativistic and Quantum Cryptography

Lead Research Organisation: University of Cambridge
Department Name: Applied Maths and Theoretical Physics

Abstract

The project will develop the theory of existing and new protocols
in relativistic and quantum cryptography. It will develop
protocols and security analyses for real world (as well as ideal)
implementations. The work will include collaboration with
Dr Damian Pitalua-Garcia (Cambridge) and with colleagues
in Cambridge and elsewhere in the UK via the UK Quantum
Communications Hub.

Publications

10 25 50

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/V52024X/1 01/10/2020 31/10/2025
2436006 Studentship EP/V52024X/1 01/10/2020 30/09/2024 George Cowperthwaite
 
Description The first discovery arose from a need to verify whether two parties share singlet states, these being a common type of entanglement used in quantum protocols. It is crucial to efficiently determine whether the parties share singlet states, otherwise many common quantum protocols could be corrupted by external noise or adversarial action. I concluded that a new type of 'random measurement' test was superior in most natural scenarios to the conventional Braunstein-Caves/CHSH based test. The natural scenarios I investigated included those where an adversary either corrupts the singlet state with quantum operations or instead replaces the singlet with a system governed by classical local hidden variables.

My second discovery was an improvement on the theoretical security bounds of a quantum token scheme developed by others in my research group. I proved that the scheme was significantly more secure than previously known, even when assuming an adversary has powers beyond usual capabilities. This improvement in security means that the quantum tokens scheme has a provable advantage over classical equivalents when sending tokens across much smaller distances than previously thought.
Exploitation Route The outcome of my first discovery may be used as a rationale for considering a 'random measurement' style test for singlet states. This is a procedure which has utility in a wide range of quantum applications where entanglement is utilised and a more efficient verification scheme would be of significant value in reducing use of resources.

The outcome of my second discovery may be used to support proposals to physically develop the quantum tokens scheme in question and provide a reassurance of security for those wishing to implement the scheme in future.
Sectors Digital/Communication/Information Technologies (including Software),Security and Diplomacy
URL https://arxiv.org/abs/2211.13750