# 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.

## Key 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.