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We investigate the coherence properties of an atomic beam evaporatively cooled in a magnetic guide, assuming thermal equilibrium in the quantum degenerate regime. The gas experiences two-dimensional, transverse Bose-Einstein condensation rather than a full three-dimensional condensation because of the very elongated geometry of the magnetic guide. First(More)
A quantum fluid passing an obstacle behaves differently from a classical one. When the flow is slow enough, the quantum gas enters a superfluid regime, and neither whirlpools nor waves form around the obstacle. For higher flow velocities, it has been predicted that the perturbation induced by the defect gives rise to the turbulent emission of quantized(More)
Resonant laser scattering along with photon correlation measurements established the atom-like character of quantum dots. Here, we show that for a wide range of experimental parameters it is impossible to isolate elementary quantum-dot excitations from a strong influence of nuclear spins; the absorption lineshapes at magnetic fields exceeding 1 T indicate(More)
We theoretically investigate the optical response of a one-dimensional array of strongly nonlinear optical microcavities. When the optical nonlinearity is much larger than both losses and intercavity tunnel coupling, the nonequilibrium steady state of the system is reminiscent of a strongly correlated Tonks-Girardeau gas of impenetrable bosons. Signatures(More)
We report numerical evidence of Hawking emission of Bogoliubov phonons from a sonic horizon in a flowing one-dimensional atomic Bose-Einstein condensate. The presence of Hawking radiation is revealed from peculiar long-range patterns in the density-density correlation function of the gas. Quantitative agreement between our fully microscopic calculations and(More)
We study the electromagnetic force exerted on a pair of parallel slab waveguides by the light propagating through them. The dependence of the force on the separation of the slabs is calculated by means of the Maxwell–Stress tensor formalism and its main features are discussed for the different modes of the radiation. Spatially symmetric (antisymmetric)(More)
We analyze the nonequilibrium dynamics of a gas of interacting photons in an array of coupled dissipative nonlinear cavities when driven by a pulsed external coherent field. Using a mean-field approach, we show that the response of the system is strongly sensitive to the underlying (equilibrium) quantum phase transition from a Mott insulator to a superfluid(More)
We present a numerically tractable method to solve exactly the evolution of a N boson system with binary interactions. The density operator of the system ρ is obtained as the stochastic average of particular operators |Ψ 1 Ψ 2 | of the system. The states |Ψ 1,2 are either Fock states |N : φ 1,2 or coherent states |coh : φ 1,2 with each particle in the state(More)
We study radiation-matter interaction in a system of ultracold atoms trapped in an optical lattice in a Mott insulator phase. We develop a fully general quantum model, and we perform calculations for a one-dimensional geometry at normal incidence. Both two-and three-level Λ atomic configurations are studied. The polariton dispersion and the reflectivity(More)
We present a new exact method to numerically compute the thermodynamical properties of an interacting Bose gas in the canonical ensemble. As in our previous paper (Phys. Rev. A 63 023606 (2001)), we write the density operator ρ as an average of Hartree dyadics |N : φ 1 N : φ 2 | and we find stochastic evolution equations for the wave functions φ 1,2 such(More)