Abstract

We study models of itinerant spinless fermions with random long-range interactions. We motivate such models from descriptions of fermionic atoms in multi-mode optical cavities. The solution of an infinite-range model yields a metallic phase which has glassy charge dynamics, and a localized glass phase with suppressed density of states at low energies. We compare these phases to the conventional disordered Fermi liquid, and the insulating electron glass of semiconductors. Prospects for the realization of such glassy phases in cold atom systems are discussed.

Highlights

  • There is much current interest in experiments with ultracold atoms and photons that provide clean realizations of models from condensed matter physics

  • The hope is that these quantum optics experiments eventually reach the parameter regimes and accuracy necessary to allow for predictions that can overcome the limitations of conventional theoretical approaches for strongly interacting quantum many-body systems

  • II, starting from a Jaynes-Cummings type Hamiltonian for itinerant fermions coupled to cavity photons, we derive the fermionic model that we study in this paper: H =−t i, j c†i c j + h.c

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Summary

INTRODUCTION

There is much current interest in experiments with ultracold atoms and photons that provide clean realizations of models from condensed matter physics. In a series of remarkable experiments at ETH Zurich [2,3,4], Baumann et al, have begun the quantum-simulation of strongly-interacting quantum gases with genuine long-range interactions [5] In these many-body cavity QED systems, an atomic ensemble (a thermal cloud [6, 7] or Bose-Einstein condensate) is loaded into an optical cavity containing quantized photon modes. An important hallmark of such insulating electron glasses is the Efros-Shklovskii gap in the single particle density of states in the glassy phase, whose elementary charge excitations are strongly Anderson localized Such a pseudogap is required by the stability of metastable states in the presence of unscreened long range interactions [28]. In the context of Coulomb frustrated systems in condensed matter (without disorder), an intermediate metallic phase with periodic, striped density order (”conducting crystal”) was discussed by Spivak and Kivelson [37]

Overview of key results and outline of paper
INSULATING ANDERSON-EFROS-SHKLOVSKII GLASS
Low density: n 1
Numerical results for metallic glass: phase diagram and density response
Dynamic density response in the metallic glass
Fermionic quasiparticles in the metallic glass
The role of fractality for the glass transition
CONCLUSION
Replica approach
Cavity approach: local selfconsistent action
Generalized Miller-Huse type analysis
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