Radiofrequency spectroscopy of one-dimensional trapped Bose polarons: crossover from the adiabatic to the diabatic regime

TL;DR

This paper explores how radio frequency pulses affect the dynamics of one-dimensional Bose polarons, revealing spectral features, impurity interactions, and the transition from adiabatic to diabatic regimes relevant for cold-atom experiments.

Contribution

It provides a detailed spectral analysis of Bose polarons under rf pulses, highlighting the crossover from adiabatic to diabatic regimes and impurity interaction effects.

Findings

Spectral resolution of polaronic excitations and mode-couplings.

Observation of temporal orthogonality catastrophe at strong repulsion.

Identification of side-band resonances for heavy impurities.

Abstract

We investigate the crossover of the impurity-induced dynamics, in trapped one-dimensional Bose polarons subject to radio frequency (rf) pulses of varying intensity, from an adiabatic to a diabatic regime. Utilizing adiabatic pulses for either weak repulsive or attractive impurity-medium interactions, a multitude of polaronic excitations or mode-couplings of the impurity-bath interaction with the collective breathing motion of the bosonic medium are spectrally resolved. We find that for strongly repulsive impurity-bath interactions, a temporal orthogonality catastrophe manifests in resonances in the excitation spectra where impurity coherence vanishes. When two impurities are introduced, impurity-impurity correlations, for either attractive or strong repulsive couplings, induce a spectral shift of the resonances with respect to the single impurity. For a heavy impurity, the polaronic peak is accompanied by a series of equidistant side-band resonances, related to interference of the impurity spin dynamics and the sound waves of the bath. In all cases, we enter the diabatic transfer regime for an increasing bare Rabi frequency of the rf field with a Lorentzian spectral shape featuring a single polaronic resonance. The findings in this work on the effects of external trap, rf pulse and impurity-impurity interaction should have implications for the new generations of cold-atom experiments.