Harnessing quantum physics has promised powerful and advanced technologies, such as guaranteed secure communications and computational processing beyond that of any classical computer. Photons – single quanta of light – present a promising platform to realise these quantum technologies. Common to all quantum platforms, the non-deterministic nature of generating, manipulating and measuring photons results in the ‘scaling catastrophe’ severely limiting the size of any composite system.
We address this scaling issue with the creation of a quantum optical memory. Such a device is capable of storing and recalling photons on demand, allowing for the synchronisation of heralded probabilistic processes via temporal multiplexing. The quantum memory can be used to store photons output from successful operations while the remaining components of the composite system are run. Once each component has successfully executed, the photons can be released from the QMs simultaneously and the next quantum task can proceed.
The main objective of this action was to produce resources for the building of a large-scale quantum photonic network. The proposed resources were (1) heralded single-photon sources, and (2) integrated chip-scale solid-state quantum memories. Importantly, the memories focused on efficiency as well as telecommunication compatibility – wavelength (1550nm), bandwidth (GHz) and propagation time (ms).
Benefits to society:
Large-scale quantum-based networks are well placed to benefit academic, industrial and commercial sectors, and indeed our society. Firstly, global area quantum networks would provide guaranteed secure communications based on quantum key distribution and quantum repeating. Therefore, this technology will revolutionise online security, allowing for unconditionally secure monetary transactions in banking, retail, and the stock market. With cybercrime and identity theft a continental threat, this technology would have a palpable impact on people's quality of life and furthermore, would have a major impact on the effectiveness of intelligence services in combating terrorism.
Secondly, local area photonic networks could lead to quantum computers that offer exponential speed-ups over classical devices. This technology has the potential to transform methods of research in the healthcare, pharmaceutical and green energy sectors. It could assist epidemiology and genetic research, cut costs in medication design, and help improve artificial light-harvesting devices for alternative energy sources, for example by permitting simulations of efficient photosynthesis. This technology will have an immediate impact on any research and innovation at the molecular level, where classical computers are ineffectual and time-consuming, leaving expensive empirical methods the only option. In the next coming decades, these emergent quantum-enhanced technologies will foster the generation of IP, the creation of spin-out companies and jobs, contributing to the productivity of the UK economy, and competitiveness globally.
