Quantum glass of interacting bosons with off-diagonal disorder

TL;DR

This paper investigates how off-diagonal disorder in the Bose-Hubbard model induces a spin-glass-like phase with frozen quantum phases, using advanced theoretical and numerical methods, relevant for quantum simulation experiments.

Contribution

It introduces a novel study of off-diagonal disorder effects in interacting bosons, revealing a spin-glass-like phase and providing phase diagrams with potential experimental realizations.

Findings

Disorder induces a spin-glass-like ground state with frozen phases.

Phase diagrams show a glassy state influenced by disorder, quantum, and thermal fluctuations.

The system can be realized experimentally in optical lattices with controlled randomness.

Abstract

We study disordered interacting bosons described by the Bose-Hubbard model with Gaussian-distributed random tunneling amplitudes. It is shown that the off-diagonal disorder induces a spin-glass-like ground state, characterized by randomly frozen quantum-mechanical U(1) phases of bosons. To access criticality, we employ the "$n$-replica trick", as in the spin-glass theory, and the Trotter-Suzuki method for decomposition of the statistical density operator, along with numerical calculations. The interplay between disorder, quantum and thermal fluctuations leads to phase diagrams exhibiting a glassy state of bosons, which are studied as a function of model parameters. The considered system may be relevant for quantum simulators of optical-lattice bosons, where the randomness can be introduced in a controlled way. The latter is supported by a proposition of experimental realization of the system in question.