Jason Smith (Oxford)
Bose-Einstein Condensation of just a few photons
Photons, like all bosons, exhibit Bose-Einstein condensation above a critical phase-space density. Most commonly in experiment, this is done with interacting bosons, typically atoms, but it has also been demonstrated in systems of photons in dye-filled optical microcavities. One of the key differences between atomic BEC and photon BEC which will be interesting for my work, is that in photon BEC there is continuous pumping and loss making a driven-dissipative condensate.
My work will start by looking at microscopic mirrors created using a focussed ion beam mill (FIB). These mirrors have much smaller radii of curvature than those typically used in photon BEC, which leads to an expected critical number of photons at 300K ranging from 100 down to around 10 - pushing at the textbook definition of BEC as ‘macroscopic’ occupation of the ground state mode. Once BEC has been achieved with mirrors created using FIB, this technique will be used to make mirrors which define different types of confining potential, allowing for study of different types of condensates of light.