Chip-based Quantum Networking

This project falls within the EPSRC quantum technologies research area.

This project involves designing, simulating and testing an integrated photonics based entangled photon pair source for an entanglement distribution network. The aim is to generate photons in a Bell state that are suitable to be used in an entanglement swapping process.

The source is also to compatible with existing fibre-optic infrastructure so that it can be deployed in a many-user/large-scale network similar to that of the existing classical internet.

The hope of creating such a large-scale quantum networks is to create secure channels of communications that are resilient to eavesdroppers and those who wish to use information for malicious purposes. Current data encryption methods used in the Internet are not safe from the threats of quantum computers.

Quantum computers have the potential, by using quantum properties such as entanglement, to compute certain types of problems exponentially faster than a classical computer.

One such problem is the factoring of large prime numbers, which currently takes an unfeasible amount of time for a classical computer so such large prime numbers are used to encrypt transmission keys.

By also using quantum properties, quantum key distribution (QKD) provides a means of transmitting encryption keys that are secure from even the threat of quantum computers. The most imminent use of large-scale quantum networks is to implement QKD across many concurrent users.

As of now the difficulties of large-scale quantum networks are high losses and instability that are hindering the ability to build such networks.

A chip-scale photon-pair source will help alleviate some of the stability issues by providing photons with a longer coherence time.

This improves the chances of an entanglement swapping process that is used in entanglement distribution networks compared to using a bulk optics source that is traditionally used.

The process of creating such a source will first require knowledge of theory of integrated silicon photonics, quantum theory, quantum information theory and QKD protocols.

It will require knowledge on specific photonic components used in the chip, specifically how to model and simulate the components in order to specify performance characteristics.

There will be extensive lab work in order to test and characterise individual components and thereafter the full chip after it has been fabricated. The lab work will require safe and competent use of fibre optics, lasers and single photon detectors.