Fermionization of a Few-Body Bose System Immersed into a Bose-Einstein Condensate

TL;DR

This paper investigates the phase transitions and fermionization phenomena in a quasi-one-dimensional two-component Bose system immersed in a Bose-Einstein condensate, revealing a first-order transition and superfluid states.

Contribution

It introduces a detailed analysis of the self-pinning transition with finite intraspecies interactions, including an analytical model for superfluidity and a comprehensive phase diagram.

Findings

Fermionization occurs via a first-order phase transition.

An additional superfluid state can emerge when interspecies interactions dominate.

The phase diagram is mapped out for small atom numbers.

Abstract

We study the recently introduced self-pinning transition [Phys. Rev. Lett. 128, 053401 (2022)] in a quasi-one-dimensional two-component quantum gas in the case where the component immersed into the Bose-Einstein condensate has a finite intraspecies interaction strength. As a result of the matter-wave backaction, the fermionization in the limit of infinite intraspecies repulsion occurs via a first-order phase transition to the self-pinned state, which is in contrast to the asymptotic behavior in static trapping potentials. The system also exhibits an additional superfluid state for the immersed component if the interspecies interaction is able to overcome the intraspecies repulsion. We approximate the superfluid state in an analytical model and derive an expression for the phase transition line that coincides with well-known phase separation criteria in binary Bose systems. The full phase diagram of the system is mapped out numerically for the case of two and three atoms in the immersed component.