Nonuniversal equation of state for Rabi-coupled bosonic gases: a droplet phase

TL;DR

This paper derives an analytical equation of state for Rabi-coupled bosonic gases, revealing how nonuniversal interaction corrections influence the formation and stability of self-bound droplet phases.

Contribution

It provides explicit expressions for the equation of state including nonuniversal corrections and analyzes droplet stability conditions in Rabi-coupled bosonic gases.

Findings

Gaussian fluctuations prevent collapse in certain regimes

Nonuniversal corrections control droplet stability

Conditions for stable self-bound droplets are established

Abstract

Through an effective quantum field theory including zero temperature Gaussian fluctuations we derive analytical and explicit expressions for the equation of state of three-dimensional ultracold Rabi-coupled two-component bosonic gases with nonuniversal corrections to the interactions. At mean-field level the system presents two ground-states, one symmetric and one non-symmetric or unbalanced. For the symmetric ground state, in the regime where inter-species interactions are weakly attractive and subtly higher than repulsive intra-species, the instability by collapse is avoided by the contribution arising from Gaussian fluctuations, driving thus to formation of a liquidlike phase or droplet phase. This self-bound state is crucially affected by the dependence on the nonuniversal corrections to the interactions, which acts controlling the droplet stability. By tuning the ratio between the inter-species scattering length and the intra-species scattering lengths or the nonuniversal contribution to the interactions we address and establish conditions under which the formation and stability of self-bound Rabi-coupled droplets with nonuniversal corrections to the interactions is favorable.