Spin Hall mode in a trapped thermal Rashba gas

We theoretically investigate a two-dimensional harmonically-trapped gas of identical atoms with Rashba spin-orbit coupling and no interatomic interactions. In analogy with the spin Hall effect in uniform space, the gas exhibits a spin Hall mode. In particular, in response to a displacement of the center-of-mass of the system, spin-dipole moment oscillations occur. We determine the properties of these oscillations exactly, and find that their amplitude strongly depends on the spin-orbit coupling strength and the quantum statistics of the particles

Light-induced effective magnetic fields for ultracold atoms in planar geometries

We propose a scheme to create an effective magnetic field for ultracold atoms in a planar geometry. The setup allows the experimental study of classical and quantum Hall effects in close analogy to solid-state systems including the possibility of finite currents. The present scheme is an extention of the proposal in Phys. Rev. Lett. 93, 033602 (2004), where the effective magnetic field is now induced for three-level Lambda-type atoms by two counterpropagating laser beams with shifted spatial profiles. Under conditions of electromagnetically induced transparency the atom-light interaction has a space-dependent dark state, and the adiabatic center-of-mass motion of atoms in this state experiences effective vector and scalar potentials. The associated magnetic field is oriented perpendicular to the propagation direction of the laser beams. The field strength achievable is one flux quantum over an area given by the transverse beam separation and the laser wavelength. For a sufficiently dilute gas the field is strong enough to reach the lowest Landau level regime

Spinor Slow-Light and Dirac particles with variable mass

We consider the interaction of two weak probe fields of light with an atomic ensemble coherently driven by two pairs of standing wave laser fields in a tripod-type linkage scheme. The system is shown to exhibit a Dirac-like spectrum for light-matter quasi-particles with multiple dark-states, termed spinor slow-light polaritons (SSP). They posses an "effective speed of light" given by the group-velocity of slow-light, and can be made massive by inducing a small two-photon detuning. Control of the two-photon detuning can be used to locally vary the mass including a sign flip. This allows e.g. the implementation of the random-mass Dirac model for which localized zero-energy (mid-gap) states exist with unsual long-range correlations.Comment: 5 pages, 4 figure

Quantum Trajectory method for the Quantum Zeno and anti-Zeno effects

We perform stochastic simulations of the quantum Zeno and anti-Zeno effects for two level system and for the decaying one. Instead of simple projection postulate approach, a more realistic model of a detector interacting with the environment is used. The influence of the environment is taken into account using the quantum trajectory method. The simulation of the measurement for a single system exhibits the probabilistic behavior showing the collapse of the wave-packet. When a large ensemble is analysed using the quantum trajectory method, the results are the same as those produced using the density matrix method. The results of numerical calculations are compared with the analytical expressions for the decay rate of the measured system and a good agreement is found. Since the analytical expressions depend on the duration of the measurement only, the agreement with the numerical calculations shows that otherparameters of the model are not important.Comment: 12 figures, accepted for publication in Phys. Rev. A replaced with single-spaced versio

Photonic band-gap properties for two-component slow light

We consider two-component "spinor" slow light in an ensemble of atoms coherently driven by two pairs of counterpropagating control laser fields in a double tripod-type linkage scheme. We derive an equation of motion for the spinor slow light (SSL) representing an effective Dirac equation for a massive particle with the mass determined by the two-photon detuning. By changing the detuning the atomic medium acts as a photonic crystal with a controllable band gap. If the frequency of the incident probe light lies within the band gap, the light tunnels through the sample. For frequencies outside the band gap, the transmission probability oscillates with increasing length of the sample. In both cases the reflection takes place into the complementary mode of the probe field. We investigate the influence of the finite excited state lifetime on the transmission and reflection coefficients of the probe light. We discuss possible experimental implementations of the SSL using alkali atoms such as Rubidium or Sodium.Comment: 7 figure

Filled Landau levels in neutral quantum gases

We consider the signatures of the Integer Quantum Hall Effect in a degenerate gas of electrically neutral atomic fermions. An effective magnetic field is achieved by applying two incident light beams with a high orbital angular momentum. We show how states corresponding to completely filled Landau levels are obtained and discuss various possibilities to measure the incompressible nature of the trapped two-dimensional gasComment: Minor corrections. Phys. Rev. A, 053632 (2005). High resolution figures can be obtained from the author