Non-Markovian probes in ultracold gases

TL;DR

This paper investigates how two different qubit models decohere in an ultracold Bose-Einstein condensate environment, revealing distinct non-Markovian behaviors and implications for quantum probing and reservoir engineering.

Contribution

It demonstrates that two similar qubit models decohere differently in a BEC, providing insights into non-Markovian dynamics and environmental spectral effects.

Findings

Different decoherence behaviors for the two qubit models

Identification of conditions for non-Markovian dynamics

Impact of thermal fluctuations on qubit coherence

Abstract

We present a detailed investigation of the dynamics of two physically different qubit models, dephasing under the effect of an ultracold atomic gas in a Bose-Einstein condensed (BEC) state. We study the robustness of each qubit probe against environmental noise; even though the two models appear very similar at a first glance, we demonstrate that they decohere in a strikingly different way. This result holds significance for studies of reservoir engineering as well as for using the qubits as quantum probes of the ultracold gas. For each model we study whether and when, upon suitable manipulation of the BEC, the dynamics of the qubit can be described by a (non-)Markovian process and consider the the effect of thermal fluctuations on the qubit dynamics. Finally, we provide an intuitive explanation for the phenomena we observe in terms of the spectral density function of the environment.