Quantum critical behavior of the superfluid-Mott glass transition

Abstract

We investigate the zero-temperature superfluid to insulator transitions in a diluted two-dimensional quantum rotor model with particle-hole symmetry. We map the Hamiltonian onto a classical $(2+1)$-dimensional XY model with columnar disorder which we analyze by means of large-scale Monte Carlo simulations. For dilutions below the lattice percolation threshold, the system undergoes a generic superfluid-Mott glass transition. In contrast to other quantum phase transitions in disordered systems, its critical behavior is of conventional power-law type with universal (dilution-independent) critical exponents $z=1.52(3)$, $\nu =1.16(5)$, $\beta /\nu =0.48(2)$, $\gamma /\nu =2.52(4)$, and $\eta =-0.52(4)$. These values agree with and improve upon earlier Monte-Carlo results [Phys. Rev. Lett. 92, 015703 (2004)] while (partially) excluding other findings in the literature. As a further test of universality, we also consider a soft-spin version of the classical Hamiltonian. In addition, we study the percolation quantum phase transition across the lattice percolation threshold; its critical behavior is governed by the lattice percolation exponents in agreement with recent theoretical predictions. We relate our results to a general classification of phase transitions in disordered systems, and we briefly discuss experiments.

10 pages, 12 figures, final version as published

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Cited by in corpus (11)

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• Inhomogeneous mean-field approach to collective excitations in disordered interacting bosons
• Localization of the Higgs mode at the superfluid-Mott glass transition
• Monte Carlo simulations of the disordered three-color quantum Ashkin-Teller chain
• Phases and Phase Transitions of the Disordered Quantum Clock Model
• Universal conductivity at a 2d superconductor-insulator transition: the effects of quenched disorder and Coulomb interaction
• Quantum Phases of a Weakly Disordered Josephson Ladder
• Scalar susceptibility of a diluted classical XY model
• Critical Behavior and Collective Modes at the Superfluid Transition in Amorphous Systems
• Quantum transitions from superfluid to insulating phases in disordered Bose systems
• Amplitude mode at the superfluid-insulator transition on a random lattice