Multiple Self-Organized Phases and Spatial Solitons in Cold Atoms Mediated by Optical Feedback

Abstract

We study the transverse self-structuring of a cloud of cold atoms with effective atomic interactions mediated by a coherent driving beam retro-reflected by means of a single mirror. The resulting self-structuring due to optomechanical forces is much richer than that of an effective-Kerr medium, displaying hexagonal, stripe and honeycomb phases depending on the interaction strength parametrized by the linear susceptibility. Phase domains are described by real Ginzburg-Landau amplitude equations. In the stripe phase the system recovers inversion symmetry. Moreover, the subcritical character of the honeycomb phase allows for light-density feedback solitons functioning as self-sustained dark atomic traps with motion controlled by phase gradients in the driving beam.

Self-Organization in Cold Atoms Mediated by Diffractive Coupling

“…For the experimental situations with dominating optomechanical and electronic nonlinearity, the inversion symmetry is broken from the start and hence hexagons are the structures obtained at threshold as indicated in Figures 1 and 3. For a Kerr nonlinearity this was explicitly calculated in [129], for an optomechanical model including velocity damping via an external molasses in [130]. Interestingly, in the latter model, inversion symmetry is reestablished at a critical coupling strength and a transition from honeycomb to hexagonal via stripe structures is obtained in the atomic density changing the linear phase shift [130].…”

“…For a Kerr nonlinearity this was explicitly calculated in [129], for an optomechanical model including velocity damping via an external molasses in [130]. Interestingly, in the latter model, inversion symmetry is reestablished at a critical coupling strength and a transition from honeycomb to hexagonal via stripe structures is obtained in the atomic density changing the linear phase shift [130]. This confirms that the optomechanical system is richer than just being an 'artificial Kerr'-medium [74] due to the transport character of the nonlinearity.…”

Rotating and spiralling spatial dissipative solitons of light and cold atoms

“…Here we show that a phase structured input can be used to engineer transport of self trapped atoms along complex trajectories, such as rotating or spiralling motion in the transverse plane, and to probe multi-soliton interactions resulting in stable soliton clusters. These considerations are also expected to apply to the dark and bright solitons in cold atoms predicted in a single-feedback-mirror (SFM) scheme [26].…”

“…Schemes involving cold atomic gases in longitudinally pumped cavities or single-mirror systems have been recently investigated theoretically and experimentally [7], and shown to achieve light-atom self-structuring, where the relevant coupling involves optomechanical (dipole) forces [8][9][10][11], electronic [12,13] and magnetic transitions [14][15][16][17]. In particular, the collective nature of optomechanical self-structuring has provided insight into several aspects of cold and ultracold atom physics such as crystallization [18][19][20], supersolidity with continuous symmetry breaking [21][22][23], photon-mediated interactions with tunable range [24], and structural transitions between crystalline configurations [25,26].…”

Limit Cycles and Chaos in the Hybrid Atom-Optomechanics System

“…The system is also applicable for metrology [16][17][18] and quantum simulations 19,20 . Last but not least, it provides a new platform to create new states of many-body physics, such as the spontaneous crystallization of atoms and light into a structure that features phonon-like excitations and bears similarities to a supersolid [21][22][23][24][25] . This motivates the further study of this system to potentially realize marvelous dynamical phases such as time crystal and chaos.…”