Lithium niobate integrated quantum photonics

Lead Research Organisation: University of Cambridge
Department Name: Materials Science & Metallurgy


Quantum information science has the potential to revolutionise information and communications technologies (ICT) in the 21st century via secure communication, precision measurement, and ultra-powerful simulation and ultimately computation. Photonics is destined for a central role - the photon is an ideal quantum bit, or 'qubit', for encoding, processing, and transmitting quantum information. However, real-world applications require integrated photonic devices, incorporating photon sources, detectors and circuits. Just as the invention of the silicon integrated circuit turned the tremendous potential of the transistor into reality, this project aims to develop all necessary components to the high levels of performance and integration required to realise quantum photonic technologies. This project will be the first to simultaneously address all components and their integration simultaneously. It will thereby overcome the major challenges to realising the tremendous potential of future quantum technologies.

A key challenge in the development and application of our approach is to integrate waveguide circuits with active components: single-photon sources, phase- and amplitude-modulators and high-efficiency single-photon detectors. Our initial benchmarking and characterisation results have identified lithium niobate (LN) as the perfect material system in which to realise all of these components and thereby to create a new paradigm for integrated quantum photonics. The goals of this proposal are to fabricate all of the key devices in the LN material system and to integrate them to realise the first prototype systems. Telecom wavelength operation will enable interfacing with existing telecom systems (existing fibre optic networks for example) and the adoption of powerful telecom technologies (modulators, wavelength division multiplexing, arrayed waveguide gratings, etc.).

The devices and systems developed in this programme will revolutionise approaches to photonic quantum technologies, paving the way to practical applications. This project brings together all of the essential expertise required to achieve these ambitious goals in world-leading groups in quantum photonic technologies and LN device fabrication (Bristol), superconducting single-photon detectors (Heriot-Watt), and superconducting thin film growth and nanofabrication (Cambridge). This proposal builds on successful work within and between these groups and has substantial support from our exisiting industrial partners (The UK National Physical Laboratory, Nokia and Quantum Technology Research Ltd.). Over the last several years the applicants have already made great strides towards integrated quantum photonic technologies, developing waveguide-on-chip quantum photonic circuits, combined with practical superconducting single photon detectors, and non-linear photon sources.

This research proposal is extremely timely in addressing a critical bottleneck in the development of optical quantum information technologies: a single material system that can support all of the required components and their integration. Our research programme will provide a launching pad to a new generation of compact, high performance quantum photonic devices operating at telecom wavelengths. We adopt a highly novel and ambitious approach in migrating from silica-on-silicon waveguide circuits to LN waveguide circuits. This will enable us to integrate periodically poled lithium niobate (PPLN) photon sources, rapidly reconfigurable waveguide circuits and high performance superconducting single-photon detectors together for the first time, and to achieve high performance operation at telecom wavelengths. This approach promises a new technology platform for realising secure communication networks, precision measurement systems, simulation of important physical, chemical and biological systems, including new materials and pharmaceuticals, and ultimately ultra-powerful computers.
Description Our work has focused on the development and understanding of amorphous superconducting films and, in particular Mo-Si, for nanowire single-photon detectors. Fabrication has been optimised, and film characterisation has advanced. We have now transferred these capabilities to our colleagues in Glasgow, who will continue with detector development based upon these materials, including uniform large area focal plane arrays and integration with quantum photonic waveguide circuits.
Exploitation Route Our thin film development can be applied to general advancements in photon detector technology; e.g. uniform large area focal plane arrays, and integration with quantum photonic waveguide circuits. Ultimately, photon detection is a requirement for quantum communication and quantum computing, besides potential new applications in biological imaging, remote sensing and astronomy.
More generally, we have advanced the science of amorphous thin film fabrication and understanding, and this could have much wider impact.
Sectors Digital/Communication/Information Technologies (including Software),Electronics

Description This work has been step on the road to the application of quantum technologies utilising photons. Optimized materials are essential components for the necessary devices, and we demonstrated clearly the potential for use of amorphous thin film nano-wires as photon sensors, and highlighted the remaining issues to be overcome. Impact will come from, for example, quantum secure communications, and novel methods for medical imaging.
First Year Of Impact 2016