Observation of disorder-induced superfluidity

TL;DR

This paper demonstrates experimentally that disorder can induce superfluidity in a quantum system with multiple energy levels per site, challenging the typical suppression of long-range coherence by disorder.

Contribution

It provides the first experimental evidence of disorder-induced superfluidity in a controlled quantum processor with qutrits, exploring the interplay of disorder, interactions, and kinetic energy.

Findings

Identification of non-ergodic glassy phases

Observation of a superfluid phonon mode in disordered systems

Distinction between Mott insulator and superfluid phases

Abstract

The emergence of states with long-range correlations in a disordered landscape is rare, as disorder typically suppresses the particle mobility required for long-range coherence. But when more than two energy levels are available per site, disorder can induce resonances that locally enhance mobility. Here we explore phases arising from the interplay between disorder, kinetic energy, and interactions on a superconducting processor with qutrit readout and control. Compressibility measurements distinguish an incompressible Mott insulator from surrounding compressible phases and reveal signatures of glassiness, reflected in non-ergodic behavior. Spatially-resolved two-point correlator measurements identify regions of the phase diagram with a non-vanishing condensate fraction. We also visualize the spectrum by measuring the dynamical structure factor. A linearly-dispersing phonon mode materializes in the superfluid, appearing even when disorder is introduced to the clean Mott insulator. Our results provide strong experimental evidence for disorder-induced superfluidity.