Atomic Switchable Cavity Quantum Memory Through Induced Two Photon Dispersion

Abstract

Photonic quantum computing offers a potential avenue to scalable fault tolerant quantum computing, however the realisation of such a device has been hampered by the need to overcome non-deterministic elements in photonic quantum information processing. A possible solution to this is the use of scalable quantum memories. There are many proposals for quantum memories but to date none of them have met all the performance requirements for effective photonic synchronisation applications. These include low noise, readout on-demand, high efficiency and broad signal acceptance bandwidth. For scalability, the quantum memory will also preferably operate at room temperature and in a platform that can be miniaturised and integrated. Quantum memories have traditionally been based upon a system where a quantum optical signal is mapped to a stationary medium in an absorption based memory, however recent development have led to the formation of quantum memories based upon switchable cavities. Here through a time varying switch, an optical signal can be mapped to a storage cavity for on-demand storage and release. Alkali vapour systems have a rich history in quantum memories due to their high optical depths allowing for strong absorption and storage of the optical signal to an ensemble of atoms. Absorption is accompanied by dispersion and therefore, this thesis explores induced dispersion in hot rubidium vapour, in order to create optically induced switching for switchable cavity quantum memory. This thesis is primarily theoretical in nature, where initially switchable cavity quantum memory is explored in the bad cavity limit through a switchable input-output coupler to the cavity. The thesis then explores two possible avenues using induced two photon dispersion in warm rubidium vapour to build such switchable couplers. Finally, progress in building an experimental platform to implement low-loss switching through a variable switching ring cavity is explored.

Date of Award	22 Jun 2022
Original language	English
Awarding Institution	University of Bath
Supervisor	Joshua Nunn (Supervisor) & Peter Mosley (Supervisor)