Cold atoms in cavity-generated dynamical optical potentials

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.Comment: 55 page review pape

Phases of cold atoms interacting via photon-mediated long-range forces

“…Differing from these systems, however, the dynamics of atomic gases in optical cavities is typically dissipative and nontrivial effects can only be observed if either the atoms or the cavity are pumped by light [2,7]. The steady state, when it exists, results from the dynamical interplay between drive and losses and its properties thus depend on the drive and on the cavity parameters.…”

“…Selforganization of the atomic gas in ordered spatial patterns occurs in a single-mode standing-wave resonator when the atoms are driven by lasers whose intensity exceeds a threshold value, which depends also on the cavity decay rate [2,8,9,10,11]. By suitably tuning the laser frequency, moreover, a stationary state exists which is characterised by a Maxwell-Boltzmann distribution of the atomic momentum.…”

Ultracold Fermions in a Cavity-Induced Artificial Magnetic Field

“…In order to overcome this difficulty, in this work the dynamical feedback between atoms and an optical cavity is employed to reach a self-organization of topologically non-trivial phases. One fascinating example for a selforganization of a coupled atom-cavity system has been realized recently by placing a bosonic quantum gas into an optical high-finesse resonator subjected to a perpendicular off-resonant pump beam [10][11][12][13][14]. Above a critical pump strength, the occupation of the cavity mode is stabilized and the bosonic atoms organize into a checkerboard density pattern [12].…”

“…Above a critical pump strength, the occupation of the cavity mode is stabilized and the bosonic atoms organize into a checkerboard density pattern [12]. Many different proposals have been put forward to realize the self-organization of more complex quantum phases [13] reaching from the Mott-insulator [15] over fermionic phases [16][17][18][19][20] and disordered structures [21][22][23][24] to phases with spin-orbit coupling [25][26][27].…”

Manipulating nanoscale atom–atom interactions with cavity QED

“…In general,there is a possibility of cavity-photon mediated long-range interaction [9,10,11,12,13,14,15] between atoms. This occurs due to transitions at a singleatom level.…”