Engineering quantum light-matter interactions in solid-state platforms

Abstract

Optical quantum technologies are a cornerstone of many scalable quantum information processing architectures, such as quantum computation and communication networks. However, scaling up these such systems to support large quantum states is challenging due to the probabilistic nature of photonic quantum operations. Optical quantum memories - devices capable of storing and releasing light on-demand - have been identified as a solution to this scalability issue through the use of multiplexing schemes. Ensembles of solid-state quantum emitters are a promising medium for the implementation of a quantum memory, especially due to their compatibility with integrated devices.

In this thesis, we focus on the development of platforms enhancing the performance of current solid-state quantum memories. The atomic frequency comb (AFC) protocol is an attractive approach to quantum light storage in solid-state media. Here, we demonstrate an implementation of the AFC rephasing technique in Pr3+:Y2SiO5 in a novel broadband regime. We also report on initial results towards the realisation of broadband memory employing cascaded two-photon absorption in the system.

Ensembles of nitrogen-vacancy centres in diamond are a promising alternative to Pr3+:Y2SiO5, due to long spin coherence times and a large ground state splitting. Nitrogen-vacancy centres were investigated as a host for a broadband implementation of the AFC protocol. We demonstrate spectral hole burning based on optically-induced ionisation of the negative charge state of the defect. Using this technique, an atomic frequency comb is successfully prepared, paving the way for the development of an AFC quantum memory in this platform.

Another approach to light-matter interactions in atomic ensembles is investigated in the form of systems based on atomic arrays. We theoretically study collective phenomena in arrays of nitrogen-vacancy centres, focusing on a promising use case where a single defect can be strongly coupled to an optical cavity composed of atomic mirrors.

Date of Award	26 Nov 2020
Original language	English
Awarding Institution	University of Bristol
Supervisor	Joshua Nunn (Supervisor) & Jonathan C F Matthews (Supervisor)