Advancing Quantum Communications using Next-Generation Optical Fibre

Secure communication technologies are the backbone of today's digital economy yet the security of current cryptographic tools, which are applied to protect global communications travelling across a network of optical fibre, is based on 'computational complexity'. This assumes an eavesdropper has limited computational resources to break complex mathematical problems. This assumption is invalidated in the coming quantum computing era and thus, urgent action is needed to ensure the continued security of our communication systems.
Quantum key distribution (QKD) is a rapidly maturing technology that solves this problem by distributing secret digital keys using quantum light. As a frontier technology, the development of QKD systems is inherently multidisciplinary. This requires the careful fusion of quantum physics, high-speed electronics, low-loss photonics and high-performance software to generate, manipulate and measure light.
While QKD has already been successfully deployed to many optical networks worldwide, this has always employed "standard" single-mode telecommunication fibre. Recently, there has been great progress in the development of nextgeneration optical fibres, using novel physical designs to achieve very different optical guidance characteristics. Such geometries include hollow-core and fewmode fibres, which offer many advantages for optical communications. This enables, for example, spatial division multiplexing to enhance the classical datacarrying capacity of fibre and reduction of nonlinear and dispersive effects, as well as reduced latency. Such new fibres could also offer many benefits for quantum communications, but these have yet to be explored.A PhD project based at Toshiba Europe Ltd is available to perform pioneering research into the development of quantum communication systems that exploit next-generation optical fibres. The project will commence with detailed optical characterisation of new types of optical fibres, measuring various linear and onlinear optical phenomena with a focus on how these affect the interaction between classical and quantum light signals. The candidate will then play a leading role in the experimental development of full QKD systems, designing, building and characterising optical transmitter and receiver modules to be connected by new types of optical fibre. This will involve extensive experimental research, combining both high-speed optical and electronic devices, in addition to developing control software. It is expected that the candidate will develop broad expertise with semiconductor lasers, short-pulse generation, optical modulation, high-speed RF electronics, linear and nonlinear fibre optics, quantum photonics, and single-photon photodetection. There are also opportunities for theoretical work to simulate and optimise optical systems and the underlying quantum communication protocols.