Analogue cosmological particle creation in an ultracold quantum fluid of light
Abstract: It is thought that the rapid expansion of the early universe resulted in the spontaneous production of cosmological particles. The latter evolved into the patterns in the cosmic microwave background visible today. The analogue of cosmological particle creation in a quantum fluid could provide insight, but an observation was not achieved previously. This talk presents our observation of analogue cosmological particle creation in a 3-dimensional quantum fluid of light. The process is seen to be spontaneous, and in close quantitative agreement with the quantum-field theoretical prediction. We find that the long-wavelength particles provide a window to early times, and we apply this principle to the cosmic microwave background. This work introduces a new quantum fluid, as cold as an atomic Bose-Einstein condensate.