Out of equilibrium correlation functions of quantum anisotropic XY models: one-particle excitations

We calculate exactly matrix elements between states that are not eigenstates of the quantum XY model for general anisotropy. Such quantities therefore describe non equilibrium properties of the system; the Hamiltonian does not contain any time dependence. These matrix elements are expressed as a sum of Pfaffians. For single particle excitations on the ground state the Pfaffians in the sum simplify to determinants.Comment: 11 pages, no figures; revtex. Minor changes in the text; list of refs. modifie

Entanglement between atomic condensates in an optical lattice: effects of interaction range

We study the area-dependent entropy and two-site entanglement for two state Bose-Einstein condensates in a 2D optical lattice. We consider the case where the array of two component condensates behave like an ensemble of spin-half particles with the interaction to its nearest neighbors and next nearest neighbors. We show how the Hamiltonian of their Bose-Einstein condensate lattice with nearest-neighbor and next-nearest-neighbor interactions can be mapped into a harmonic lattice. We use this to determine the entropy and entanglement content of the lattice.Comment: 5 pages, 3 figures, title change

Symmetry breaking in small rotating cloud of trapped ultracold Bose atoms

We study the signatures of rotational and phase symmetry breaking in small rotating clouds of trapped ultracold Bose atoms by looking at rigorously defined condensate wave function. Rotational symmetry breaking occurs in narrow frequency windows, where the ground state of the system has degenerated with respect to the total angular momentum, and it leads to a complex wave function that exhibits vortices clearly seen as holes in the density, as well as characteristic vorticity. Phase symmetry (or gauge symmetry) breaking, on the other hand, is clearly manifested in the interference of two independent rotating clouds.Comment: 4 pages, 2 figure

One-Dimensional Impenetrable Anyons in Thermal Equilibrium. II. Determinant Representation for the Dynamic Correlation Functions

We have obtained a determinant representation for the time- and temperature-dependent field-field correlation function of the impenetrable Lieb-Liniger gas of anyons through direct summation of the form factors. In the static case, the obtained results are shown to be equivalent to those that follow from the anyonic generalization of Lenard's formula.Comment: 16 pages, RevTeX

Ordered structures in rotating ultracold Bose gases

The characterization of small samples of cold bosonic atoms in rotating microtraps has recently attracted increasing interest due to the possibility to deal with a few number of particles per site in optical lattices. We analyze the evolution of ground state structures as the rotational frequency $\Omega$ increases. Various kinds of ordered structures are observed. For $N<10$ atoms, the standard scenario, valid for large sytems, is absent, and only gradually recovered as $N$ increases. The vortex contribution to the total angular momentum $L$ as a function of $\Omega$ ceases to be an increasing function of $\Omega$, as observed in experiments of Chevy {\it et al.} (Phys. Rev. Lett. 85, 2223 (2000)). Instead, for small $N$, it exhibits a sequence of peaks showing wide minima at the values of $\Omega$, where no vortices appear.Comment: 35 pages, 17 figure

Off-diagonal correlations in one-dimensional anyonic models: A replica approach

We propose a generalization of the replica trick that allows to calculate the large distance asymptotic of off-diagonal correlation functions in anyonic models with a proper factorizable ground-state wave-function. We apply this new method to the exact determination of all the harmonic terms of the correlations of a gas of impenetrable anyons and to the Calogero Sutherland model. Our findings are checked against available analytic and numerical results.Comment: 19 pages, 5 figures, typos correcte

Accretion Disks Around Young Objects. II. Tests of Well-Mixed Models with Ism Dust

We construct detailed vertical structure models of irradiated accretion disks around T Tauri stars with interstellar medium dust uniformly mixed with gas. The dependence of the structure and emission properties on mass accretion rate, viscosity parameter, and disk radius is explored using these models. The theoretical spectral energy distributions (SEDs) and images for all inclinations are compared with observations of the entire population of Classical T Tauri stars (CTTS) and Class I objects in Taurus. In particular, we find that the median near-infrared fluxes can be explained within the errors with the most recent values for the median accretion rates for CTTS. We further show that the majority of the Class I sources in Taurus cannot be Class II sources viewed edge-on because they are too luminous and their colors would be consistent with disks seen only in a narrow range of inclinations. Our models appear to be too geometrically thick at large radii, as suggested by: (a) larger far-infrared disk emission than in the typical SEDs of T Tauri stars; (b) wider dark dust lanes in the model images than in the images of HH30 and HK Tau/c; and (c) larger predicted number of stars extincted by edge-on disks than consistent with current surveys. The large thickness of the model is a consequence of the assumption that dust and gas are well-mixed, suggesting that some degree of dust settling may be required to explain the observations.Comment: 41 pages, 13 figures, accepted in Ap

One-Dimensional Impenetrable Anyons in Thermal Equilibrium. IV. Large Time and Distance Asymptotic Behavior of the Correlation Functions

This work presents the derivation of the large time and distance asymptotic behavior of the field-field correlation functions of impenetrable one-dimensional anyons at finite temperature. In the appropriate limits of the statistics parameter, we recover the well-known results for impenetrable bosons and free fermions. In the low-temperature (usually expected to be the "conformal") limit, and for all values of the statistics parameter away from the bosonic point, the leading term in the correlator does not agree with the prediction of the conformal field theory, and is determined by the singularity of the density of the single-particle states at the bottom of the single-particle energy spectrum.Comment: 26 pages, RevTeX

Three-tangle for mixtures of generalized GHZ and generalized W states

We give a complete solution for the three-tangle of mixed three-qubit states composed of a generalized GHZ state, a|000>+b|111>, and a generalized W state, c|001>+d|010>+f|100>. Using the methods introduced by Lohmayer et al. we provide explicit expressions for the mixed-state three-tangle and the corresponding optimal decompositions for this more general case. Moreover, as a special case we obtain a general solution for a family of states consisting of a generalized GHZ state and an orthogonal product state

Scissors mode of trapped dipolar gases

We study the scissors modes of dipolar boson and fermion gases trapped in a spherically symmetric potential. We use the harmonic oscillator states to solve the time-dependent Gross-Pitaevskii equation for bosons and the time-dependent Hartree-Fock equation for fermions. It is pointed out that the scissors modes of bosons and fermions can be of quite different nature