Superfluid-Superfluid Phase Transitions in Two-Component Bose System

TL;DR

This paper investigates phase transitions between different superfluid states in a two-component Bose system, revealing their universal properties and mapping their critical behavior to known single-component transitions.

Contribution

It introduces a unified framework for understanding the quantum phase transitions among superfluid phases in two-component bosons, highlighting their universal critical behavior.

Findings

2SF-PSF and 2SF-SCF transitions can be mapped onto each other.

Their universality class matches the (d+1)-dimensional normal-superfluid transition.

Finite-temperature transitions and interface properties are discussed.

Abstract

Depending on the Hamiltonian parameters, two-component bosons in an optical lattice can form at least three different superfluid phases in which both components participate in the superflow: a (strongly interacting) mixture of two miscible superfluids (2SF), a paired superfluid vacuum (PSF), and (at a commensurate total filling factor) the super-counter-fluid state (SCF). We study universal properties of the 2SF-PSF and 2SF-SCF quantum phase transitions and show that (i) they can be mapped onto each other, and (ii) their universality class is identical to the (d+1)-dimensional normal-superfluid transition in a single-component liquid. Finite-temperature 2SF-PSF(SCF) transitions and the topological properties of 2SF-PSF(SCF) interfaces are also discussed.