Probing and Manipulating Fermionic and Bosonic Quantum Gases with Quantum Light

TL;DR

This paper explores the quantum interaction between light and ultracold atomic gases in optical lattices, demonstrating how photon detection can measure quantum correlations, generate macroscopic superpositions, and reveal new quantum phases.

Contribution

It introduces a comprehensive analysis of atom-light interactions in the quantum regime, including entanglement, quantum nondemolition measurements, and the impact of quantum lattice dynamics on phase diagrams.

Findings

Photon detection enables QND measurement of atomic quantum states.

Entanglement between light and matter can produce Schrödinger cat states.

Quantum lattice dynamics lead to novel quantum phases and altered phase diagrams.

Abstract

We study the atom-light interaction in the fully quantum regime, with focus on off-resonant light scattering into a cavity from ultracold atoms trapped in an optical lattice. The detection of photons allows the quantum nondemolition (QND) measurement of quantum correlations of the atomic ensemble, distinguishing between different quantum states. We analyse the entanglement between light and matter and show how it can be exploited for realising multimode macroscopic quantum superpositions such as Schr\"odinger cat states, for both bosons and fermions. We provide examples utilising different measurement schemes, and study their robustness to decoherence. Finally, we address the regime where the optical lattice potential is a quantum dynamical variable and is modified by the atomic state, leading to novel quantum phases, and significantly altering the phase diagram of the atomic system.