Self-organization in cold atomic gases: a synchronization perspective (original) (raw)

Self-Organization in Cold Atoms Mediated by Diffractive Coupling

arXiv (Cornell University), 2021

This article discusses self-organization in cold atoms via light-mediated interactions induced by feedback from a single retro-reflecting mirror. Diffractive dephasing between the pump beam and the spontaneous sidebands selects the lattice period. Spontaneous breaking of the rotational and translational symmetry occur in the 2D plane transverse to the pump. We elucidate how diffractive ripples couple sites on the self-induced atomic lattice. The nonlinear phase shift of the atomic cloud imprinted onto the optical beam is the parameter determining coupling strength. The interaction can be tailored to operate either on external degrees of freedom leading to atomic crystallization for thermal atoms and supersolids for a quantum degenerate gas, or on internal degrees of freedom like populations of the excited state or Zeeman sublevels. Using the light polarization degrees of freedom on the Poincaré sphere (helicity and polarization direction), specific irreducible tensor components of the atomic Zeeman states can be coupled leading to spontaneous magnetic ordering of states of dipolar and quadrupolar nature. The requirements for critical interaction strength are compared for the different situations. Connections and extensions to longitudinally pumped cavities, counterpropagating beam schemes and the CARL instability are discussed.

Optomechanical self-organization in cold atomic gases

2013 Sixth "Rio De La Plata" Workshop on Laser Dynamics and Nonlinear Photonics, 2013

We discuss the formation of optomechanical structures from the interaction between linear dielectric scatterers and a light field via dipole forces without the need for optical nonlinearities. The experiment uses a high density sample of Rb atoms in a single mirror feedback geometry. We observe hexagonal structures in the light field and a complementary honeycomb pattern in the atomic density. Different theoretical approaches are discussed assuming either viscous damping of the atomic velocity or not. The interplay between electronic and optomechanical nonlinearities is analyzed. A prediction for dissipative light -matter density solitons is given. The investigations demonstrate novel prospects for the manipulation of matter in a pattern forming system in which quantum effects should be accessible.

Cold Atomic Gases in Optical Lattices with Disorder

2007

Cold atomic gases placed in optical lattices enable studies of simple condensed matter theory models with parameters that may be tuned relatively easily. When the optical potential is randomized (e.g. using laser speckle to create a random intensity distribution) one may be able to observe Anderson localization of matter waves for non-interacting bosons, the so-called Bose glass in the presence of interactions, as well as the Fermi glass or quantum spin glass for mixtures of fermions and bosons.

Collective atomic recoil laser as a synchronization transition

Physical Review E, 2008

We consider here a model previously introduced to describe the collective behavior of an ensemble of cold atoms interacting with a coherent electromagnetic field. The atomic motion along the selfgenerated spatially-periodic force field can be interpreted as the rotation of a phase oscillator. This suggests a relationship with synchronization transitions occurring in globally coupled rotators. In fact, we show that whenever the field dynamics can be adiabatically eliminated, the model reduces to a self-consistent equation for the probability distribution of the atomic "phases". In this limit, there exists a formal equivalence with the Kuramoto model, though with important differences in the self-consistency conditions. Depending on the field-cavity detuning, we show that the onset of synchronized behavior may occur through either a first-or second-order phase transition. Furthermore, we find a secondary threshold, above which a periodic self-pulsing regime sets in, that is immediately followed by the unlocking of the forward-field frequency. At yet higher, but still experimentally meaningful, input intensities, irregular, chaotic oscillations may eventually appear. Finally, we derive a simpler model, involving only five scalar variables, which is able to reproduce the entire phenomenology exhibited by the original model.

Non-equilibrium coherence dynamics in one-dimensional Bose gases

Nature, 2007

Low-dimensional systems are beautiful examples of many-body quantum physics . For onedimensional systems the Luttinger liquid approach provides insight into universal properties. Much is known of the equilibrium state, both in the weakly and strongly interacting regime. However, it remains a challenge to probe the dynamics by which this equilibrium state is reached . Here we present a direct experimental study of the coherence dynamics in both isolated and coupled degenerate 1d Bose gases. Dynamic splitting is used to create two 1d systems in a phase coherent state . The time evolution of the coherence is revealed in local phase shifts of the subsequently observed interference patterns. Completely isolated 1d Bose gases are observed to exhibit a universal subexponential coherence decay in excellent agreement with recent predictions by Burkov et al. . For two coupled 1d Bose gases the coherence factor is observed to approach a non-zero equilibrium value as predicted by a Bogoliubov approach . This coupled-system decay to finite coherence is the matter wave equivalent of phase locking two lasers by injection. The non-equilibrium dynamics of superfluids plays an important role in a wide range of physical systems, such as superconductors, quantum-Hall systems, superfluid Helium, and spin systems . Our experiments studying coherence dynamics show that 1d Bose gases are ideally suited for investigating this class of phenomena.

Fast Dynamics for Atoms in Optical Lattices

Physical Review Letters, 2013

Cold atoms in optical lattices allow for accurate studies of many body dynamics. Rapid timedependent modifications of optical lattice potentials may result in significant excitations in atomic systems. The dynamics in such a case is frequently quite incompletely described by standard applications of tight-binding models (such as e.g. Bose-Hubbard model or its extensions) that typically neglect the effect of the dynamics on the transformation between the real space and the tight-binding basis. We illustrate the importance of a proper quantum mechanical description using a multi-band extended Bose-Hubbard model with time-dependent Wannier functions. We apply it to situations, directly related to experiments. PACS numbers: 67.85.Hj, 03.75.Kk, 03.75.Lm

Momentum-resolved study of an array of 1D strongly phase-fluctuating Bose gases

Arxiv preprint arXiv: …, 2010

We investigate the coherence properties of an array of one-dimensional Bose gases with shortscale phase fluctuations. The momentum distribution is measured using Bragg spectroscopy and an effective coherence length of the whole ensemble is defined. In addition, we propose and demonstrate that time-of-flight absorption imaging can be used as a simple probe to directly measure the coherence-length of 1D gases in the regime where phase-fluctuations are strong. This method is suitable for future studies such as investigating the effect of disorder on the phase coherence. PACS numbers: 67.85.De,05.30.Jp

From coherent to incoherent dynamical behaviour of quantum atomic gases in periodic potentials

Applied Numerical Mathematics, 2004

In seminal experiments performed in 1995, alkali atomic gases have been cooled to nanokelvin temperatures to form a new state of matter which shows macroscopic quantum coherence and Bose-Einstein condensation. We give a physics-oriented view of diverse transport behaviours of these Bose-Einstein condensates, which can be explored after solving a nonlinear Schrödinger equation by means of an explicit time-marching algorithm. Coherent and decoherent transport behaviour in periodic potentials is reviewed and new aspects related to chaotic nonlinear dynamics are anticipated.