Silica microbubble resonators: a platform for cavity-enhanced quantum photonics

  • Ross Challinor

Student thesis: Doctoral ThesisPhD


Photonics is a key enabling technology for quantum computation, both in the context of photonic quantum processors and photonic interconnects within hybrid networks. Progress necessitates the realisation of larger, more complex photonic quantum architectures and with that the requirement that individual elements operate at high efficiencies. Crucial to the operation of such systems are the sources of indistinguishable high-purity single photon states that acts as their inputs.

The work presented explores microresonators, specifically silica microbubble resonators, as high-quality single photon sources and as hosts for low-intensity light-matter interaction as a stepping-stone to the modification of photon statistics through two-photon absorption. The first part of this thesis is dedicated to theoretically modelling such devices for the generation of pairs of single photons through spontaneous four wave mixing. Typically, these devices have extremely high quality whispering gallery mode resonances, features that make them well-suited for this application. Also investigated is how, through two-photon absorption within the resonator, the photon number statistics of such sources could be further improved in an application of the quantum Zeno effect.

To explore the device characteristics first-hand, microbubble devices were fabricated with quality factors exceeding 10 million by inflating thin-walled silica capillary using a commercial fibre splicer.

One such microbubble device was filled with IR-125 dye molecules suspended in benzyl ethanol. Two photon absorption of circulating light was then observed by detecting emission from the dye, this data being used to infer a lower bound of 18.59±1.23GM for the absorption cross section of the dye at 1550nm.
Date of Award13 Sept 2023
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorPeter Mosley (Supervisor) & Joshua Nunn (Supervisor)

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