Excited-state quantum phase transitions in spin-orbit coupled Bose gases

TL;DR

This paper proposes using Raman-dressed spin-orbit coupled Bose gases as a new platform to detect and explore excited-state quantum phase transitions through measurable density modulations, advancing experimental capabilities.

Contribution

It introduces a novel approach to study excited-state quantum phase transitions using spin-orbit coupled gases and defines a new excited-state phase characterized by density stripes.

Findings

The dressed system is equivalent to a spinor gas with tunable interactions.

A new excited-state phase characterized by density modulations is defined.

The properties of this phase can be used to prepare stable stripe states.

Abstract

Excited-state quantum phase transitions depend on and reveal the structure of the whole spectrum of many-body systems. While they are theoretically well understood, finding suitable signatures and detect them in actual experiments remains challenging. For instance, in spinor gases, excited-state phases have been identified and characterized through a topological order parameter that is challenging to measure in experiments. Here, we propose the Raman-dressed spin-orbit coupled gas as a novel platform to explore excited-state quantum phase transitions. In a weakly-coupled regime, the dressed system is equivalent to a spinor gas with tunable spin-spin interactions. Through this equivalence we are able to define a new excited-state phase of the dressed gas. The phase is characterize by the the behavior of the spatial density modulations, or stripes, induced by spin-orbit coupling, and can in principle be measured in current state-of-the-art experiments with ultracold atoms. Conversely, we show that the properties of the excited phase can be exploited to prepare stripe states with large and stable density modulations.