Single-photon-level atomic frequency comb quantum memory in warm rubidium vapour

Abstract

Quantum memories are devices that allow for the on-demand storage and retrieval of photonic quantum information. They are crucial devices in the realisation of quantum communication networks and are also used for synchronising qubit inputs for photonic quantum computers.

This thesis reviews the current state of the field of quantum memories, including an assessment of the current platforms and protocols used before critiquing the current state-of-the-art research within the quantum memory community.

The main research undertaken for this thesis revolves around the Atomic Frequency Comb (AFC) memory protocol within warm Rubidium 87 vapour. The thesis then explores the theory behind this protocol, describes how this protocol is implemented experimentally, and presents the results, which demonstrate the storage of short pulses of light with high intensity and also at the single-photon level.

The limits of the AFC protocol are also investigated. The limits include (a) the dependence of the protocol on different pumping preparation regimes, (b) the optical depth of the atoms, and (c) the single photon limit. The compatibility of this memory with polarisation and time-bin qubits is also demonstrated, providing the groundworks for this quantum memory to store true single-photon qubits.

This thesis lays the groundwork for integrating this protocol with a quantum dot single-photon source to allow for fidelity measurements.

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Identifiers

ORCID for Patrick Ledingham: orcid.org/0000-0002-9804-6132

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