Investigating polaron transitions with polar molecules

TL;DR

This paper explores the complex phase transitions of a mixed polaron model with experimental relevance, revealing richer physics than pure models and proposing ultracold molecules as a platform for study.

Contribution

It introduces a detailed phase diagram for a mixed polaron model and demonstrates how ultracold molecules can be used to experimentally investigate these phenomena.

Findings

Two sharp phase transitions in the mixed polaron model.

Experimental parameters can access the transition region.

Proposed measurement scheme using stimulated Raman spectroscopy.

Abstract

We determine the phase diagram of a polaron model with mixed breathing-mode and Su-Schrieffer-Heeger couplings and show that it has two sharp transitions, in contrast to pure models which exhibit one (for Su-Schrieffer-Heeger coupling) or no (for breathing-mode coupling) transition. Our results indicate that the physics of realistic mixed polaron models is much richer than that of simplified models. We then show that ultracold molecules trapped in optical lattices can be used to study precisely this mixed Hamiltonian, and that the relative contributions of the two couplings can be tuned with external electric fields. The parameters of current experimental set-ups place them in the region where one of the transitions occurs. We propose a scheme to measure the polaron dispersion using stimulated Raman spectroscopy.