Light scattering from an atomic gas under conditions of quantum degeneracy

TL;DR

This paper develops a quantum theory for elastic light scattering in a Bose-Einstein condensate, revealing polariton transport and comparing it with classical Maxwell predictions.

Contribution

It introduces a quantum scattering framework for BECs, capturing polariton dynamics and extending beyond classical light scattering models.

Findings

Polariton wave transport in BECs demonstrated

Quantum scattering equation derived and numerically solved

Differences from classical Maxwell theory analyzed

Abstract

We consider a quantum theory of elastic light scattering from a macroscopic atomic sample existing in the Bose-Einstein condensate (BEC) phase. The dynamics of the optical excitation induced by an incident photon is influenced by the presence of incoherent scattering channels. For a sample of sufficient length the excitation transports as a polariton wave and the propagation Green's function obeys the scattering equation which we derive. The polariton dynamics could be tracked in the outgoing channel of the scattered photon as we show via numerical solution of the scattering equation for one-dimensional geometry. The results are analyzed and compared with predictions of the conventional macroscopic Maxwell theory for light scattering from a non-degenerate atomic sample of the same density and size.