Weakly interacting Bose gas with two-body losses

TL;DR

This paper investigates the dynamics of weakly interacting Bose gases with two-particle losses, revealing novel dissipative phenomena, corrections, and symmetries, and validating the approach with numerical simulations.

Contribution

It introduces a Lindblad master equation with complex scattering length for dissipative Bose gases and uncovers new dynamical properties and symmetries.

Findings

Dissipative analogs of known Bose gas results are identified.

Next-order correction to decay rate scales with |n a_c^3|^{1/2}.

A dynamical symmetry group Sp(4,C) is discovered in the system.

Abstract

We study the many-body dynamics of weakly interacting Bose gases with two-particle losses. We show that both the two-body interactions and losses in atomic gases may be tuned by controlling the inelastic scattering process between atoms by an optical Feshbach resonance. Interestingly, the low-energy behavior of the scattering amplitude is governed by a single parameter, i.e. the complex $s$-wave scattering length $a_c$. The many-body dynamics are thus described by a Lindblad master equation with complex scattering length. We solve this equation by applying the Bogoliubov approximation in analogy to the closed systems. Various peculiar dynamical properties are discovered, some of them may be regarded as the dissipative counterparts of the celebrated results in closed Bose gases. For example, we show that the next-order correction to the mean-field particle decay rate is to the order of $|n a_c^{3}|^{1/2}$, which is an analogy of the Lee-Huang-Yang correction of Bose gases. It is also found that there exists a dynamical symmetry of symplectic group Sp$(4,\mathbb{C})$ in the quadratic Bogoliubov master equation, which is an analogy of the SU(1,1) dynamical symmetry of the corresponding closed system. We further confirmed the validity of the Bogoliubov approximation by comparing its results with a full numerical calculation in a double-well toy model. Generalizations of other alternative approaches such as the dissipative version of the Gross-Pitaevskii equation and hydrodynamic theory are also discussed in the last.