Cold atoms in cavity-generated dynamical optical potentials

TLDR

Cold atoms in high‑finesse optical resonators experience a nonlinear, back‑action‑driven dynamics that can cool, confine, and mediate long‑range interactions, enabling collective phenomena. This review surveys state‑of‑the‑art theory and experiments on cold‑atom motion in the dispersive regime of resonators and explores how quantum‑degenerate gases can emulate optomechanics and novel quantum phases such as supersolids and spin glasses. The systems studied involve cold and ultracold atoms coupled to the cavity field with small internal excitation, where the optical dipole force and atomic motion back‑act on the light, and quantum gases inside the resonator provide controllable long‑range interactions. Cavity output provides sub‑wavelength, minimally perturbative real‑time position monitoring, reveals correlated motion, critical behavior, and non‑equilibrium phase transitions, and enables non‑destructive probing of Hubbard physics and tailoring of long‑range interactions.

Abstract

We review state-of-the-art theory and experiment of the motion of cold and ultracold atoms coupled to the radiation field within a high-finesse optical resonator in the dispersive regime of the atom-field interaction with small internal excitation. The optical dipole force on the atoms together with the back-action of atomic motion onto the light field gives rise to a complex nonlinear coupled dynamics. As the resonator constitutes an open driven and damped system, the dynamics is non-conservative and in general enables cooling and confining the motion of polarizable particles. In addition, the emitted cavity field allows for real-time monitoring of the particle's position with minimal perturbation up to sub-wavelength accuracy. For many-body systems, the resonator field mediates controllable long-range atom-atom interactions, which set the stage for collective phenomena. Besides correlated motion of distant particles, one finds critical behavior and non-equilibrium phase transitions between states of different atomic order in conjunction with superradiant light scattering. Quantum degenerate gases inside optical resonators can be used to emulate opto-mechanics as well as novel quantum phases like supersolids and spin glasses. Non-equilibrium quantum phase transitions, as predicted by e.g. the Dicke Hamiltonian, can be controlled and explored in real-time via monitoring the cavity field. In combination with optical lattices, the cavity field can be utilized for non-destructive probing Hubbard physics and tailoring long-range interactions for ultracold quantum systems.