Prethermalization in the cooling dynamics of an impurity in a BEC

TL;DR

This paper investigates how heavy impurity atoms cool within a Bose-Einstein condensate through Cherenkov phonon emission, revealing pre-thermalized states and potential for impurity mass detection and non-equilibrium state preparation.

Contribution

It introduces a detailed analysis of impurity cooling dynamics in BECs, highlighting the formation of pre-thermalized states and their dependence on mass ratios, advancing understanding of impurity behavior in superfluids.

Findings

Pre-thermalized impurity states are formed with distinct momentum regions.

Superfluidity causes separation of thermalization time-scales.

Impurity momentum distributions can be manipulated for non-equilibrium states.

Abstract

We discuss the cooling dynamics of heavy impurity atoms in a Bose-Einstein condensate (BEC) by emission of Cherenkov phonons from scattering with the condensate. In a weakly interacting, low-temperature condensate the superfluidity of the condensate results in a separation of time-scales of the thermalization dynamics. Pre-thermalized states are formed with distinct regions of impurity momenta determined by the mass ratio of impurity and BEC atoms. This can be employed to detect the mass renormalization of the impurity upon the formation of a polaron and paves the way to preparing non-equilibrium impurity-momentum distributions.