Speaker

Lewis Ruks, Research Scientist, Theoretical Quantum Physics Research Group, Basic Research Laboratories

Abstract

We establish a semiclassical phase-space description of permutation-invariant emitter ensembles with local dissipation, representing each ensemble by four phase-space variables associated with a collective spin of variable length. This description is obtained through a Wigner–Moyal expansion, yielding at leading order a scalable truncated Wigner approximation (TWA) whose stochastic dynamics can be simulated using classical Monte Carlo methods. We illustrate, in a model of pumped bad-cavity superradiance, that the TWA captures spin squeezing and subradiance, and improves on common approximations including cumulant expansions. We cast a class of spatially extended emitter systems as interacting ensembles to show how fluctuations captured in the TWA reshape directional cooperative emission beyond mean-field predictions, in a pumped chain containing tens of thousands of emitters. Our results identify a semiclassical limit for a class of microscopic quantum-optical models comprising emitter ensembles and offer a route towards studying their collective phenomena. (arXiv:2602.14025)

Looking forward to seeing many of you at the seminar!

Quantum Systems Unit