The quantum ground state of self-organized atomic crystals in optical resonators

TL;DR

This paper theoretically investigates the quantum ground state of self-organized atomic crystals in optical resonators, revealing conditions under which they exhibit Mott-insulator or superfluid phases, with potential experimental realizations.

Contribution

It maps the atomic dynamics to a Bose-Hubbard model and identifies the quantum phases of the self-organized structures depending on laser pump strength.

Findings

Quantum ground state can be Mott-insulator or superfluid.

Superfluid states occur at high pump strengths.

Potential for experimental realization of these quantum phases.

Abstract

Cold atoms, driven by a laser and simultaneously coupled to the quantum field of an optical resonator, can self-organize in periodic structures. These structures are supported by the optical lattice, which emerges from the laser light they scatter into the cavity mode, and form when the laser intensity exceeds a threshold value. We study theoretically the quantum ground state of these structures above the pump threshold of self-organization, by mapping the atomic dynamics of the self-organized crystal to a Bose-Hubbard model. We find that the quantum ground state of the self-organized structure can be the one of a Mott-insulator or a superfluid, depending on the pump strength of the driving laser. For very large pump strengths, where the intracavity intensity is maximum and one would expect a Mott-insulator state, we find intervals of parameters where the system is superfluid. These states could be realized in existing experimental setups.