Photoinduced electric currents in Bose-Einstein condensates

TL;DR

This paper investigates how Bose-Einstein condensates, specifically indirect excitons, generate light-induced electric currents when exposed to electromagnetic fields above their ionization threshold, revealing a dominant condensate-specific current component.

Contribution

It introduces a theoretical framework for understanding photoinduced currents in BECs, highlighting the role of Bogoliubov modes and identifying a unique condensate-specific current component.

Findings

Two main current components: regular and condensate-specific.

Condensate-specific current dominates at high light frequencies.

Ionization excites collective Bogoliubov modes.

Abstract

We calculate a light-induced electric current which can occur from a Bose-Einstein condensate under the action of an external electromagnetic field with the frequency exceeding the ionization potential of the bosons, taking a system of indirect excitons as a testbed. We show that the ionization can be accompanied by the excitation of collective Bogoliubov modes. As a result, the current consists of two principal components: one regular, which has a counterpart in bosonic systems in the normal phase, and the other one specific for condensates since the photoabsorption is mediated by the emission of Bogoliubov quasiparticles. Surprisingly, the latter component soon becomes predominant with the increase of light frequency above the ionization potential.