Light scattering by interacting two-level atoms (poster)

Yvan R. P. Sortais

Ziting Chen, Yifei He, Mingchen Huang +4 more

Superradiance is the coherent spontaneous emission from a many-body system, owing to its origin in the simultaneous cooperative interaction among its constituents, initially predicted by R. H. Dicke in 1954. It has been a subject of intense study in various systems, especially in atomic systems. In this poster, we will present our recent observation on superradiant light scattering in a dipolar Bose-Einstein condensate (BEC) of Er atoms [1]. We systematically investigate how s-wave and dipolar interactions affect superradiant light scattering. Our finding opens a new way of characterizing many-body quantum states with light scattering. As an example, we examine the collective light scatter across the phase transition from a dipolar BEC to a quantum droplet.

P. van der Straten, Harold J. Metcalf

Luke Masters, Xinxin Hu, Martin Cordier +5 more

Abstract The interaction of light with a single two-level emitter is the most fundamental process in quantum optics, and is key to many quantum applications. As a distinctive feature, two photons are never detected simultaneously in the light scattered by the emitter. This is commonly interpreted by saying that a single two-level quantum emitter can only absorb and emit single photons. However, it has been theoretically proposed that the photon anticorrelations can be thought of as arising from quantum interference between two possible two-photon scattering amplitudes, which one refers to as coherent and incoherent. This picture is in stark contrast to the aforementioned one, in that it assumes that the atom has two different mechanisms at its disposal to scatter two photons at the same time. Here we experimentally validate the interference picture by showing that, when spectrally rejecting only the coherent component of the fluorescence light of a single two-level atom, the remaining light consists of photon pairs that have been simultaneously scattered by the atom. Our results offer fundamental insights into the quantum-mechanical interaction between light and matter and open up novel approaches for the generation of highly non-classical light fields enabling, for example, Fourier-limited photon-pair sources that approach the theoretical limit in brightness.

Lothar Frommhold, Michael H. Proffitt