Description:

I will describe measurements of individual photons that are scattered from a cavity filled with superfluid helium. We use these photon counts to study the phonons in a single acoustic mode of the superfluid. With the acoustic mode in equilibrium, the measured phonon-phonon correlations are consistent (up to 4th order) with a thermal state having mean phonon number ~ 1. When the acoustic mode is driven resonantly, the photon-counting data shows that the purity of the acoustic mode is preserved even when its amplitude corresponds to tens of thousands of phonons. I will describe the application of these results to testing models of discrete spacetime, and to distributing entanglement over kilometer-scale optical fiber networks.

Speaker: Jack Harris, Professor, Yale University

Host: Andrew Geraci