Asymmetric sequential Landau-Zener dynamics of Bose condensed atoms in a cavity

TL;DR

This paper investigates the asymmetric Landau-Zener transitions in Bose condensed atoms coupled to a cavity, revealing photon-number-dependent effects and novel population dynamics that differ from classical field cases.

Contribution

It introduces the concept of asymmetric sequential Landau-Zener dynamics in atom-cavity systems, highlighting the role of photon-number-dependent Rabi frequencies and atom-atom interactions.

Findings

Asymmetric LZ transitions depend on photon number distribution.

Population ladders exhibit decreasing step heights with multiple excitations.

Cavity field shows collapse and revivals during LZ processes.

Abstract

We explore the asymmetric sequential Landau-Zener (LZ) dynamics in an ensemble of interacting Bose condensed two-level atoms coupled with a cavity field. Assuming the couplings between all atoms and the cavity field are identical, the interplay between atom-atom interaction and detuning may lead to a series of LZ transitions. Unlike the conventional sequential LZ transitions, which are symmetric to the zero detuning, the LZ transitions of Bose condensed atoms in a cavity field are asymmetric and sensitively depend on the photon number distribution of the cavity. In LZ processes involving single excitation numbers, both the variance of the relative atom number and the step slope of the sequential population ladder are asymmetric, and the asymmetry become more significant for smaller excitation numbers. Furthermore, in LZ processes involving multiple excitation numbers, there may appear asymmetric population ladders with decreasing step heights. During a dynamical LZ process, due to the atom-cavity coupling, the cavity field shows dynamical collapse and revivals. In comparison with the symmetric LZ transitions in a classical field, the asymmetric LZ transitions in a cavity field originate from the photon-number-dependent Rabi frequency. The asymmetric sequential LZ dynamics of Bose condensed atoms in a cavity field may open up a new way to explore the fundamental many-body physics in coupled atom-photon systems.