Collisional decoherence of internal state superpositions in a trapped ultracold gas

TL;DR

This paper presents a comprehensive analysis of collisional decoherence in ultracold gases, deriving expressions that connect decoherence rates to scattering properties, and proposes a method to measure scattering lengths via decoherence measurements.

Contribution

It provides a general theoretical framework for collisional decoherence applicable to various mass ratios and includes both elastic and inelastic collisions, enabling better estimates of decoherence rates in ultracold systems.

Findings

Derived an expression linking decoherence rate to scattering amplitudes.

Analyzed the effect of mass ratio on decoherence in ultracold gases.

Proposed a method to determine scattering lengths from decoherence measurements.

Abstract

We analyze collisional decoherence of atoms or molecules prepared in a coherent superposition of nondegenerate internal states at ultralow temperatures and placed in an ultracold buffer gas. Our analysis is applicable for an arbitrary bath particle/tracer particle mass ratio. Both elastic and inelastic collisions contribute to decoherence. We obtain an expression relating the observable decoherence rate to pairwise scattering properties, specifically the low-temperature scattering amplitudes. We consider the dependence on the bath particle/tracer particle mass ratio for the case of light bath and heavy tracer particles. The expressions obtained may be useful in low-temperature applications where accurate estimates of decoherence rates are needed. The results suggest a method for determining the scattering lengths of atoms and molecules in different internal states by measuring decoherence-induced damping of coherent oscillations.