Microwave detection using Rydberg excitons in cuprous oxide

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

Technical Work to be Undertaken

The objective of the CASE studentship with DSTL is to start a new direction based on the use of the excitonic state for sensitive microwave detection. We hope to demonstrate the excitons - bounds states of electrons and holes - can be simultaneously strongly coupled to microwave and optical radiation, enabling microwave to optical conversion and detection.

It builds on a 4 year EPSRC grant that started on 01/05/2017 (Solid State Superatoms), which is collaboration with Cardiff University (PI Dr Stephen Lynch), and which will provide the underpinning equipment. The CASE award is independent of the existing collaboration with Cardiff University, but there is some cross-over between the two projects.

Current Level of Maturity of the Work

The Durham/Cardiff collaboration has existed since 2015; we have preliminary results (observation of Rydberg excitons up to principal quantum number n=12), and developed methods for sample preparation and spectroscopy. The microwave sensing direction is underpinned to some extent by our positive experience with atomic Rydberg states, but is highly innovative and carries some degree of risk.

Expected Deliverables

As part of a CASE award, DSTL would host the student for a 3 month placement, providing access to knowledge and the potential for recruitment. Additional benefits include continuing access to expertise and advice on potential technologies. Reports can be delivered if required.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509462/1 01/10/2016 30/09/2021
1929797 Studentship EP/N509462/1 01/10/2017 30/09/2021 Liam Andrew Gallagher
 
Description Microwave detection using Rydberg excitons in cuprous oxide has been achieved. It was achieved through a Brillouin scattering process. Brillouin scattering is the scattering of light on a sound wave in a crystal. In our system, the microwave field creates a sound wave in the crystal. Our excitation light creates a polariton (exciton-photon quasiparticle) which can scatter on the sound wave. The polariton then decays and emits light. By measuring the emitted light (frequency and/or intensity) we can tell whether it has undergone this scattering event, and hence whether a microwave field was present. A paper is currently being written on this microwave enhanced scattering process.

This coupling mechanism is not the one we originally expected to see. We were expecting to see electric-dipole transitions between Rydberg states driven by the microwave field as has been previously observed in atomic Rydberg systems. However this has not yet been observed and work is on going.
Exploitation Route Microwave to optical conversion is a useful tool in classical telecommunications as well as for quantum computation. In quantum computing microwave qubits have shown a lot of promise, but readout of the microwave signal is a challenge. This system could be used a new readout mechanism for microwave qubits. As it is already at cryogenic temperatures (4K) integration with microwave qubits would be possible.
Sectors Other