Strong coupling treatment of the polaronic system consisting of an impurity in a condensate

TL;DR

This paper applies a strong coupling variational approach to a polaronic system with an impurity in a condensate, revealing Relaxed Excited States and providing simplified, accurate transition energy calculations for experimental detection.

Contribution

It introduces a simplified variational method to analyze Relaxed Excited States in impurity-condensate systems, improving accuracy over traditional approaches.

Findings

Identification of Relaxed Excited States in the energy spectrum

Derivation of approximate transition energies with good accuracy

Determination of effective mass and minimal coupling for these states

Abstract

The strong coupling treatment of the Fr\"ohlich-type polaronic system, based on a canonical transformation and a standard Landau-Pekar type variational wave function, is applied to the polaronic system consisting of an impurity in a condensate. Within this approach the Relaxed Excited States are retrieved as a typical polaronic feature in the energy spectrum. For these states we calculate the corresponding effective mass and the minimal coupling constant required for them to occur. The present approach allows to derive approximate expressions for the transition energies between different Relaxed Excited States in a much simpler way than with the full Mori-Zwanzig approach, and with a good accuracy, which improves with increasing coupling. The transition energies obtained here can be used as the spectroscopic fingerprint for the experimental observation of Relaxed Excited States of impurities in a condensate.