Universal phase diagram of disordered bosons from a doped quantum magnet

TL;DR

This paper develops a universal phase diagram for disordered bosons in doped quantum magnets, revealing the transition from localized Bose glass to superfluid phases through quantum percolation and condensation.

Contribution

It introduces a universal phase diagram for disordered bosons in quantum magnets, linking Bose glass and superfluid phases via a complex crossover.

Findings

Identification of a Bose glass phase in doped quantum magnets

Observation of a crossover from quantum percolation to condensation

Measurable signatures of superfluid onset in spin-triplet gases

Abstract

A quantum particle cannot in general diffuse through a disordered medium because of its wavelike nature, but interacting particles can escape localization by collectively percolating through the system. For bosonic particles this phenomenon corresponds to a quantum transition from a localized insulator phase - the Bose glass - to a superfluid phase, in which particles condense into an extended state. Here, we construct a universal phase diagram of disordered bosons in doped quantum magnets for which bosonic quasi-particles are represented by magnetized states (spin triplets) of the quantum spins, condensing into a magnetically ordered state. The appearance of a Bose glass leads to strong measurable signatures in the onset of superfluidity of the spin-triplet gas, exhibiting a complex crossover from low-temperature quantum percolation to a conventional condensation transition at intermediate temperatures.