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Hi everyone,
This week's mailing is late due to the Easter Monday public holiday - but
to make up for it I have included all preprints up until the Tuesday
mailing that just arrived in my inbox.
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Matt.
-- ------------------------------------------------------------------------- Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ------------------------------------------------------------------------- ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604186 Date: Thu, 6 Apr 2006 20:15:15 GMT (19kb) Title: BEC-BCS crossover in an optical lattice Authors: A. O. Koetsier, D. B. M. Dickerscheid, H. T. C. Stoof Comments: 4 pages, 3 figures Subj-class: Statistical Mechanics \\ We present the microscopic theory for the BEC-BCS crossover of an atomic Fermi gas in an optical lattice, showing that the Feshbach resonance underlying the crossover in principle induces strong multiband effects. Nevertheless, the BEC-BCS crossover itself can be described by a single-band model since it occurs at magnetic fields that are relatively far away from the Feshbach resonance. A criterion is proposed for the latter, which is obeyed by most known Feshbach resonances in ultracold atomic gases. \\ ( http://arXiv.org/abs/cond-mat/0604186 , 19kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0601148 replaced with revised version Fri, 7 Apr 2006 19:48:22 GMT (32kb) Title: Finite Size Effects in Cold Asymmetrical Fermion Superfluids Authors: Heron Caldas Comments: 4 pages, 1 figure (eps), minor corrections in the text, conclusion modified, typos corrected, references added Subj-class: Superconductivity; Strongly Correlated Electrons \\ ( http://arXiv.org/abs/cond-mat/0601148 , 32kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603489 replaced with revised version Thu, 6 Apr 2006 22:21:12 GMT (420kb) Title: Comment on "Pairing and Phase Separation in a Polarized Fermi Gas" by G. B. Partridge, W. Li, R. I. Kamar, Y. Liao, R. G. Hulet, Science 311, 503 (2006) Authors: Martin W. Zwierlein and Wolfgang Ketterle Comments: revised version with more thorough discussion on local density approximation and phase separation Subj-class: Superconductivity; Strongly Correlated Electrons \\ ( http://arXiv.org/abs/cond-mat/0603489 , 420kb) ------------------------------------------------------------------------------ \\ Paper: physics/0604061 Date: Fri, 7 Apr 2006 13:48:11 GMT (751kb) Title: 6-axis inertial sensor using cold-atom interferometry Authors: B. Canuel, F. Leduc, D. Holleville, A. Gauguet, J. Fils, A. Virdis, A. Clairon, N. Dimarcq, Ch. J. Borde, A. Landragin Comments: 4 pages, 6 figures Subj-class: Atomic Physics \\ We have developed an atom interferometer providing a full inertial base. This device uses two counter-propagating cold-atom clouds that are launched in strongly curved parabolic trajectories. Three single Raman beam pairs, pulsed in time, are successively applied in three orthogonal directions leading to the measurement of the three axis of rotation and acceleration. In this purpose, we introduce a new atom gyroscope using a butterfly geometry. We discuss the present sensitivity and the possible improvements. \\ ( http://arXiv.org/abs/physics/0604061 , 751kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604216 Date: Fri, 7 Apr 2006 23:46:01 GMT (67kb) Title: Optimal conversion of Bose condensed atoms into molecules via a Feshbach resonance Authors: Jaeyoon Jeong, Chris P. Search, and Ivana Djuric Subj-class: Other \\ In many experiments involving conversion of quantum degenerate atomic gases into molecular dimers via a Feshbach resonance, an external magnetic field is linearly swept from above the resonance to below resonance. In the adiabatic limit, the fraction of atoms converted into molecules is independent of the functional form of the sweep and is predicted to be 100%. However, for non-adiabatic sweeps through resonance, Landau-Zener theory predicts that a linear sweep will result in a negligible production of molecules. Here we employ a genetic algorithm to determine the functional time dependence of the magnetic field that produces the maximum number of molecules for sweep times that are comparable to the period of resonant atom-molecule oscillations, $2\pi\Omega_{Rabi}^{-1}$. The optimal sweep through resonance indicates that more than 95% of the atoms can be converted into molecules for sweep times as short as $2\pi\Omega_{Rabi}^{-1}$ while the linear sweep results in a conversion of only a few percent. We also find that the qualitative form of the optimal sweep is independent of the strength of the two-body interactions between atoms and molecules and the width of the resonance. \\ ( http://arXiv.org/abs/cond-mat/0604216 , 67kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604232 Date: Sun, 9 Apr 2006 09:43:22 GMT (346kb) Title: 3D strong localization of matter waves by scattering off atoms in a lattice with a confinement-induced resonance Authors: Pietro Massignan (LKB - Lhomond), Yvan Castin (LKB - Lhomond) Comments: 20 pages; 14 figures Proxy: ccsd ccsd-00022452 Subj-class: Disordered Systems and Neural Networks \\ The possibility of using ultracold atoms to observe strong localization of matter waves is now the subject of a great interest, as undesirable decoherence and interactions can be made negligible in these systems. It was proposed that a static disordered potential can be realized by trapping atoms of a given species in randomly chosen sites of a deep 3D optical lattice with no multiple occupation. We analyze in detail the prospects of this scheme for observing localized states in 3D for a matter wave of a different atomic species that interacts with the trapped particles and that is sufficiently far detuned from the optical lattice to be insensitive to it. We demonstrate that at low energy a large number of 3D strongly localized states can be produced for the matter wave, if the effective scattering length describing the interaction of the matter wave with a trapped atom is of the order of the mean distance between the trapped particles. Such high values of the effective scattering length can be obtained by using a Feshbach resonance to adjust the free space inter-species scattering length and by taking advantage of confinement-induced resonances induced by the trapping of the scatterers in the lattice. \\ ( http://arXiv.org/abs/cond-mat/0604232 , 347kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604236 Date: Sun, 9 Apr 2006 17:14:26 GMT (174kb) Title: What is a Cooper pair ? Authors: G. Ortiz and J. Dukelsky Comments: Proccedings of the International Workshop on Condensed Matter Theories held in Japan (Sept. 2005) Subj-class: Superconductivity \\ Recently, the nature of Cooper pairs in the BCS-BEC crossover has regained attention due to the observation of a large fraction of preformed fermion pairs on the BCS side of the Feshbach resonance in ultracold atomic Fermi gases. While several theoretical explanations were proposed, the interpretations are still controversial. The root of the controversy is understanding what represents a Cooper pair in a correlated Fermi system. This paper discusses these issues at the most elementary level. \\ ( http://arXiv.org/abs/cond-mat/0604236 , 174kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604241 Date: Mon, 10 Apr 2006 05:53:00 GMT (151kb) Title: Conserving Gapless Mean-Field Theory for Weakly Interacting Bose Gases Authors: Takafumi Kita Comments: 19 pages, 8 figures Subj-class: Statistical Mechanics Journal-ref: J. Phys. Soc. Jpn. 75, 044603 (2006) \\ This paper presents a conserving gapless mean-field theory for weakly interacting Bose gases. We first construct a mean-field Luttinger-Ward thermodynamic functional in terms of the condensate wave function $\Psi$ and the Nambu Green's function $\hat{G}$ for the quasiparticle field. Imposing its stationarity respect to $\Psi$ and $\hat{G}$ yields a set of equations to determine the equilibrium for general non-uniform systems. They have a plausible property of satisfying the Hugenholtz-Pines theorem to provide a gapless excitation spectrum. Also, the corresponding dynamical equations of motion obey various conservation laws. Thus, the present mean-field theory shares two important properties with the exact theory: ``conserving'' and ``gapless.'' The theory is then applied to a homogeneous weakly interacting Bose gas with s-wave scattering length $a$ and particle mass $m$ to clarify its basic thermodynamic properties under two complementary conditions of constant density $n$ and constant pressure $p$. The superfluid transition is predicted to be first-order because of the non-analytic nature of the order-parameter expansion near $T_{c}$ inherent in Bose systems, i.e., the Landau-Ginzburg expansion is not possible here. The transition temperature $T_{c}$ shows quite a different interaction dependence between the $n$-fixed and $p$-fixed cases. In the former case $T_{c}$ increases from the ideal gas value $T_{0}$ as $T_{c}/T_{0}= 1+ 2.33 an^{1/3}$, whereas it decreases in the latter as $T_{c}/T_{0}= 1- 3.84a(mp/2\pi\hbar^{2})^{1/5}$. Temperature dependences of basic thermodynamic quantities are clarified explicitly. \\ ( http://arXiv.org/abs/cond-mat/0604241 , 151kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604255 Date: Mon, 10 Apr 2006 16:33:05 GMT (33kb) Title: The Three-Boson System at Next-To-Next-To-Leading Order Authors: L. Platter, D. R. Phillips Comments: 20 pages, 3 eps figures Subj-class: Other \\ We discuss effective field theory treatments of the problem of three particles interacting via short-range forces (range R >> a_2, with a_2 the two-body scattering length). We show that forming a once-subtracted scattering equation yields a scattering amplitude whose low-momentum part is renormalization-group invariant up to corrections of O(R^3/a_2^3). Since corrections of O(R/a_2) and O(R^2/a_2^2) can be straightforwardly included in the integral equation's kernel, a unique solution for 1+2 scattering phase shifts and three-body bound-state energies can be obtained up to this accuracy. We use our equation to calculate the correlation between the binding energies of Helium-4 trimers and the atom-dimer scattering length. Our results are in excellent agreement with the recent three-dimensional Faddeev calculations of Roudnev and collaborators that used phenomenological inter-atomic potentials. \\ ( http://arXiv.org/abs/cond-mat/0604255 , 33kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0503264 replaced with revised version Mon, 10 Apr 2006 09:03:36 GMT (72kb) Title: Finite Temperature Excitations of a trapped Bose gas by Feynman-Kac path integral approach Authors: S. Datta Comments: 35pages,16figures Subj-class: Other \\ ( http://arXiv.org/abs/cond-mat/0503264 , 72kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0505374 replaced with revised version Sun, 9 Apr 2006 18:59:31 GMT (15kb) Title: Spin 1/2 Fermions in the Unitary Regime: A Superfluid of a New Type Authors: Aurel Bulgac, Joaquin E. Drut and Piotr Magierski Comments: 4 pages, 1 figure, published version Subj-class: Statistical Mechanics Journal-ref: Phys. Rev. Lett. 96, 090404 (2006) DOI: 10.1103/PhysRevLett.96.090404 \\ ( http://arXiv.org/abs/cond-mat/0505374 , 15kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0507233 replaced with revised version Mon, 10 Apr 2006 15:38:36 GMT (49kb) Title: Density distributions for trapped one-dimensional spinor gases Authors: Yajiang Hao, Yunbo Zhang, J. Q. Liang, and Shu Chen Comments: 6 pages, 3 figures, version to be published in Phys. Rev. A Subj-class: Strongly Correlated Electrons \\ ( http://arXiv.org/abs/cond-mat/0507233 , 49kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0509380 replaced with revised version Mon, 10 Apr 2006 19:58:31 GMT (27kb) Title: Vortex description of the fractionalized phase in exciton bose condensate Authors: Sung-Sik Lee, T. Senthil and Patrick A. Lee Comments: 8 pages, 6 figures; clarification made in introduction Subj-class: Strongly Correlated Electrons \\ ( http://arXiv.org/abs/cond-mat/0509380 , 27kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511675 replaced with revised version Sat, 8 Apr 2006 11:07:53 GMT (187kb) Title: Interference between independent fluctuating condensates Authors: Anatoli Polkovnikov, Ehud Altman, Eugene Demler Comments: 7 pages, 3 figures, published version Subj-class: Statistical Mechanics Journal-ref: PNAS 103, 6125 (2006) DOI: 10.1073/pnas.0510276103 \\ ( http://arXiv.org/abs/cond-mat/0511675 , 187kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604054 Date: Sun, 9 Apr 2006 05:30:09 GMT (9kb) Title: On the quantum master equation for fermions Authors: C. F. Huang and K.-N. Huang Comments: 15 pages \\ A quantum master equation is obtained for identical fermions by including a relaxation term in addition to the mean-field Hamiltonian. [C. F. Huang and K.-N. Huang, Chinese J. Phys. ${\bf 42}$, 221 (2004); Ralph Gebauer and Roberto Car, Phys. Rev. B ${\bf 70}$, 125324 (2004).] It is shown in this paper that both the positivity and Pauli exclusion principle are preserved under this quantum master equation when there exists an upper bound for the transition rate. Such an equation can be reduced to a Markoff master equation of Lindblad form in the low-density limit with respect to particles or holes. \\ ( http://arXiv.org/abs/quant-ph/0604054 , 9kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604055 Date: Sat, 8 Apr 2006 16:01:43 GMT (28kb) Title: About mathematical apparatus of many body quantum dynamics Authors: Y.I.Ozhigov Comments: 29 ges, Latex \\ We discuss the possibility to modify many-body Hilbert quantum formalism that is necessary for the representation of quantum systems dynamics. The notion of effective classical algorithm and visualization of quantum dynamics play the key role. \\ ( http://arXiv.org/abs/quant-ph/0604055 , 28kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604066 Date: Mon, 10 Apr 2006 12:06:54 GMT (1599kb) Title: Classical and Quantum Chaos in Atom Optics Authors: Farhan Saif Comments: 105 pages, 14 figures Journal-ref: Physics Reports 419, 207 (2005); Physics Reports 425, 369 (2006) \\ The interaction of an atom with an electromagnetic field is discussed in the presence of a time periodic external modulating force. It is explained that a control on atom by electromagnetic fields helps to design the quantum analog of classical optical systems. In these atom optical systems chaos may appear at the onset of external fields. The classical and quantum chaotic dynamics is discussed, in particular in an atom optics Fermi accelerator. It is found that the quantum dynamics exhibits dynamical localization and quantum recurrences. \\ ( http://arXiv.org/abs/quant-ph/0604066 , 1599kb) ------------------------------------------------------------------------------ \\ Paper: physics/0604079 Date: Mon, 10 Apr 2006 19:53:25 GMT (539kb) Title: Magnetic trapping of buffer-gas cooled chromium atoms and prospects for the extension to paramagnetic molecules Authors: Joost M. Bakker, Michael Stoll, Dennis R. Weise, Oliver Vogelsang, Gerard Meijer, and Achim Peters Comments: 8 pages, 4 Figures. Submitted to J.Phys. B, special issue on cold molecules/ Subj-class: Atomic Physics \\ We report the successful buffer-gas cooling and magnetic trapping of chromium atoms with densities exceeding 10^12 atoms per cm^3 at a temperature of 350 mK for the trapped sample. The possibilities to extend the method to buffer gas cool and magnetically trap molecules are discussed. To minimize the most important loss mechanism in magnetic trapping, molecules with a small spin-spin interaction and a large rotational constant are preferred. Both the CrH (6Sigma+ ground state) and MnH (7Sigma+) radicals appear to be suitable systems for future experiments. \\ ( http://arXiv.org/abs/physics/0604079 , 539kb) ------------------------------------------------------------------------------ \\ Paper: physics/0604077 Date: Mon, 10 Apr 2006 10:38:38 GMT (100kb) Title: Do we have enough air? Authors: V.Dorobantu Comments: 3 pages Subj-class: Physics Education \\ If only human beings would breathe the entire quantity of terrestrial air, then, at the present-day population on the Earth, one million years would exhaust that air. It seems we have enough air. Is it so? \\ ( http://arXiv.org/abs/physics/0604077 , 100kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604273 Date: Tue, 11 Apr 2006 12:24:20 GMT (267kb) Title: Topological constraints on magnetostatic traps Authors: R. Gerritsma and R. J. C. Spreeuw Comments: 7 pages, 5 figures Subj-class: Other \\ We theoretically investigate properties of magnetostatic traps for cold atoms that are subject to externally applied uniform fields. We show that Ioffe Pritchard traps and other stationary points of $B$ are confined to a two-dimensional curved manifold defined by $\det(\partial B_i/\partial x_j)=0$. We describe how stationary points can be moved over the manifold by applying external uniform fields. The manifold also plays an important role in the behavior of points of zero field. Field zeroes occur in two distinct types, in separate regions of space divided by the manifold. Pairs of zeroes of opposite type can be created or annihilated on the manifold. Finally, we give examples of the manifold for cases of practical interest. \\ ( http://arXiv.org/abs/cond-mat/0604273 , 267kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604282 Date: Tue, 11 Apr 2006 16:28:35 GMT (22kb) Title: Pair correlations of an expanding superfluid Fermi gas Authors: C. Lobo, I. Carusotto, S. Giorgini, A. Recati, S. Stringari Comments: 4 pages, 1 figure Subj-class: Soft Condensed Matter \\ The pair correlation function of an expanding gas is investigated with an emphasis on the BEC-BCS crossover of a superfluid Fermi gas at zero temperature. At unitarity quantum Monte Carlo simulations reveal the occurrence of a sizable bunching effect due to interactions in the spin up-down channel which, at short distances, is larger than that exhibited by thermal bosons in the Hanbury-Brown and Twiss effect. We propose a local equilibrium ansatz for the pair correlation function which we predict will remain isotropic during the expansion even if the trapping potential is anisotropic, contrary to what happens for non-interacting gases. This behavior is understood to be a consequence of the violation of scaling of the pair correlation function due to interactions. \\ ( http://arXiv.org/abs/cond-mat/0604282 , 22kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511709 replaced with revised version Tue, 11 Apr 2006 15:41:43 GMT (76kb) Title: Adiabatic-Impulse approximation for avoided level crossings: from phase transition dynamics to Landau-Zener evolutions and back again Authors: Bogdan Damski and Wojciech H. Zurek Comments: 12 pages & 6 figures, minor corrections, version accepted in Phys. Rev. A Report-no: LAUR# 05-8597 Subj-class: Other \\ ( http://arXiv.org/abs/cond-mat/0511709 , 76kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0602240 replaced with revised version Tue, 11 Apr 2006 08:53:21 GMT (155kb) Title: Bragg spectroscopy of trapped one dimensional strongly interacting bosons in optical lattices: Probing the cake-structure Authors: Guido Pupillo, Ana Maria Rey and G. George Batrouni Comments: 7 pages, 4 figures Subj-class: Other \\ ( http://arXiv.org/abs/cond-mat/0602240 , 155kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604074 Date: Tue, 11 Apr 2006 09:17:16 GMT (20kb) Title: Thermal limitation of far-field matter-wave interference Authors: Klaus Hornberger Comments: 8 pages, 2 figures; to appear in Phys Rev A \\ We asses the effect of the heat radiation emitted by mesoscopic particles on their ability to show interference in a double slit arrangement. The analysis is based on a stationary, phase-space based description of matter wave interference in the presence of momentum-exchange mediated decoherence. \\ ( http://arXiv.org/abs/quant-ph/0604074 , 20kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604080 Date: Tue, 11 Apr 2006 16:57:17 GMT (269kb) Title: Hawking radiation effect on fermions and information loss in black holes Authors: Doyeol Ahn Comments: Submittted to Nature on March 28, 2006 \\ Hawking radiation1-4 (quantum thermal radiation from the black hole) and its effect on information loss in black holes5-10 have been a serious challenge to modern physics because they require a clear understanding of phenomena ranging from gravity to quantum mechanics and particle physics to information theory. The essence of Hawking radiation on the scalar particles is that an observer at rest outside a black hole or a uniformly accelerated observer (Rindler spacetime) in the flat spacetime sees a thermal bath of particles11-13. On the other hand, Hawking radiation effect on fermions (particles with half-integer spin) and information loss is not so well understood. Here we report that the Hawking radiation effect on fermions is fundamentally different from the case of scalar particles. Our study shows that the intrinsic properties of fermions (exclusion principle and spin) affect strongly the interaction of fermions with both Hawking radiation and metric of the spacetime. In particular we have found the following: first, while the fermion vacuum state seen by the Rindler observer is an entangled state in which the right and left Rindler wedge states appear in correlated pairs as in the case of the scalar particles, the entanglement disappears in the excited state due to the exclusion principle; second, the spin of the fermion experiences a non-unitary Winger rotation14,15 under a uniform acceleration; and third, the quantum information of fermions is dissipated not by the Hawking radiation but by the Wigner rotation. As a result, information loss in a black hole is quite different for scalar particles and fermions. Part of the information survives for scalar particles16. For fermions, it is dissipated irreversibly into the curvature of the spacetime. \\ ( http://arXiv.org/abs/quant-ph/0604080 , 269kb) ------------------------------------------------------------------------------ \\ Paper (*cross-listing*): nucl-th/0601077 Date: Wed, 25 Jan 2006 09:04:35 GMT (88kb) Date (revised v2): Tue, 11 Apr 2006 15:18:13 GMT (90kb) Title: Nuclear quantum optics with x-ray laser pulses Authors: Thomas J. Buervenich, Joerg Evers, Christoph H. Keitel Comments: 5 pages, 3 eps figures, revised version Journal-ref: Phys. Rev. Lett. 96, 142501 (2006) \\ The direct interaction of nuclei with super-intense laser fields is studied. We show that present and upcoming high-frequency laser facilities, especially together with a moderate acceleration of the target nuclei, do allow for resonant laser-nucleus interaction. These direct interactions may be utilized for the optical measurement of nuclear properties such as the transition frequency and the dipole moment, thus opening the field of nuclear quantum optics. As ultimate goal, one may hope that direct laser-nucleus interactions could become a versatile tool to enhance preparation, control and detection in nuclear physics. \\ ( http://arXiv.org/abs/nucl-th/0601077 , 90kb) ------------------------------------------------------------------------------ \\ Paper: physics/0604082 Date: Tue, 11 Apr 2006 04:11:06 GMT (230kb) Title: Atom interferometer as a selective sensor of rotation or gravity Authors: B. Dubetsky and M. A. Kasevich Comments: 21 pages, 4 figures Subj-class: Atomic Physics \\ In the presence of Earth gravity and gravity-gradient forces, centrifugal and Coriolis forces caused by the Earth rotation, the phase of the time-domain atom interferometers is calculated with accuracy up to the terms proportional to the fourth degree of the time separation between pulses. We considered double-loop atom interferometers and found appropriate condition to eliminate their sensitivity to acceleration to get atomic gyroscope, or to eliminate the sensitivity to rotation to increase accuracy of the atomic gravimeter. Consequent use of these interferometers allows one to measure all components of the acceleration and rotation frequency projection on the plane perpendicular to gravity acceleration. Atom interference on the Raman transition driving by non-counterpropagating optical fields is proposed to exclude stimulated echo processes which can affect the accuracy of the atomic gyroscopes. Using non-counterpropagating optical fields allows one to get new type of the Ramsey fringes arising in the unidirectional Raman pulses and therefore centered at the two-quantum line center. Density matrix in the Wigner representation is used to perform calculations. It is shown that in the time between pulses, in the non-inertial frame, for atoms with fully quantized spatial degrees of freedom, this density matrix obeys classical Liouville equations. \\ ( http://arXiv.org/abs/physics/0604082 , 230kb) ------------------------------------------------------------------------------ \\ Paper: physics/0604087 Date: Tue, 11 Apr 2006 08:03:39 GMT (428kb) Title: A definitive number of atoms on demand: controlling the number of atoms in a-few-atom magneto-optical trap Authors: Seokchan Yoon, Youngwoon Choi, Sangbum Park, Jaisoon Kim, Jai-Hyung Lee, and Kyungwon An Comments: 3 pages, 4 figures Subj-class: Atomic Physics \\ A few 85Rb atoms were trapped in a micron-size magneto-optical trap with a high quadrupole magnetic-field gradient and the number of atoms was precisely controlled by suppressing stochastic loading and loss events via real-time feedback on the magnetic field gradient. The measured occupation probability of single atom was as high as 99%. Atoms up to five were also trapped with high occupation probabilities. The present technique could be used to make a deterministic atom source. \\ ( http://arXiv.org/abs/physics/0604087 , 428kb) ------------------------------------------------------------------------------ \\ Paper: physics/0604088 Date: Tue, 11 Apr 2006 10:12:43 GMT (711kb) Title: Dependence of fluorescence-level statistics on bin time size in a few-atom magneto-optical trap Authors: Sungsam Kang, Seokchan Yoon, Youngwoon Choi, Jai-Hyung Lee, and Kyungwon An Comments: 9 pages, 9 figures Subj-class: Atomic Physics \\ We have analyzed the statistical distribution of the fluorescence signal levels in a magneto-optical trap containing a few atoms and observed that it strongly depends on the relative size of the bin time with respect to the trap decay time. We derived analytic expressions for the signal distributions in two limiting cases, long and short bin time limits, and found good agreement with numerical simulations performed regardless of the size of the bin time. We found an optimal size of the bin time for minimizing the probability of indeterminate atom numbers while providing accurate information on the instantaneous number of atoms in the trap. These theoretical results are compared with actual experimental data. We observed super-Poisson counting statistics for the fluorescence from trapped atoms, which might be attributed to uncorrelated motion of trapped atoms in the inhomogeneous magnetic field in the trap. \\ ( http://arXiv.org/abs/physics/0604088 , 711kb) ------------------------------------------------------------------------------ \\ Paper: physics/0408088 replaced with revised version Tue, 11 Apr 2006 15:34:52 GMT (426kb) Title: Classical diffusion in double-delta-kicked particles Authors: M.M.A. Stocklin and T.S. Monteiro Comments: 14 pages, 10 figures Subj-class: Atomic Physics \\ ( http://arXiv.org/abs/physics/0408088 , 426kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604311 Date: Wed, 12 Apr 2006 12:58:18 GMT (27kb) Title: The exciton many-body theory extended to arbitrary composite bosons Authors: M. Combescot, O.Betbeder-Matibet, F. Dubin Subj-class: Mesoscopic Systems and Quantum Hall Effect \\ We have recently constructed a many-body theory for composite excitons, in which the possible carrier exchanges between $N$ excitons can be treated exactly through a set of dimensionless ``Pauli scatterings'' between two excitons. Many-body effects with excitons turn out to be rather simple because excitons are the exact one-electron-hole-pair eigenstates of the semiconductor Hamiltonian, thus forming a complete orthogonal set for one-pair states. It can however be of interest to extend this new many-body theory to more complicated composite bosons, \emph{i. e.}, ``cobosons'', which are not necessarily the one-pair eigenstates of the system Hamiltonian, nor even orthogonal. The purpose of this paper is to derive the ``Pauli scatterings'' and the ``interaction scatterings'' of these cobosons formally, \emph{i. e.}, just in terms of their wave functions and the interaction potentials which exist between the fermions from which they are constructed. We also explain how to derive many-body effects in this very general system of composite bosons. \\ ( http://arXiv.org/abs/cond-mat/0604311 , 27kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604312 Date: Wed, 12 Apr 2006 13:22:15 GMT (191kb) Title: Analysis of light-induced frequency shifts in the photoassociation of ultracold metastable helium atoms Authors: Maximilien Portier (LKB - Lhomond), Steven Moal (LKB - Lhomond), Jaewan Kim (LKB - Lhomond), Mich\`{e}le Leduc (LKB - Lhomond), Claude Cohen-Tannoudji (LKB - Lhomond), Olivier Dulieu (LAC) Comments: 28 pages, 7 figures, submitted to the special issue on Cold Molecules of J. Phys. B Proxy: ccsd ccsd-00022678 Subj-class: Other \\ We present an exhaustive analysis of the light-induced frequency shifts of the photoassociation lines of ultracold metastable 4He* atoms in a magnetic trap. The measurements of the shifts of several vibrational levels bound in the purely long-range J=1,0u+ potential linked to the 23S1-23P0 asymptote were reported in a previous paper and are analyzed here. The simplicity of this system makes it very appropriate for a detailed study. Indeed, the purely long-range character of the excited potential allows one to calculate exact excited molecular wavefunctions and to use asymptotic expansions at large internuclear distances of the ground state wavefunctions appearing in Franck-Condon type integrals. Moreover, the number of collisional channels to be considered is strongly reduced by the absence of hyperfine structure for 4He* and the use of polarized ultracold atoms and polarized light. This allows us to derive semi-analytical expressions for the shifts showing explicitly their linear dependences on the s-wave scattering length a of spin polarized metastable 4He* atoms. This explains how it is possible to derive the measurement of a from these shifts. \\ ( http://arXiv.org/abs/cond-mat/0604312 , 191kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604082 Date: Wed, 12 Apr 2006 08:08:21 GMT (112kb) Title: Aspects of quantum coherence in the optical Bloch equations Authors: A. S. Sanz, H. Han, and P. Brumer Comments: 18 pages, 6 figures; to appear in J Chem Phys \\ Aspects of coherence and decoherence are analyzed within the optical Bloch equations. By rewriting the analytic solution in an alternate form, we are able to emphasize a number of unusual features: (a) despite the Markovian nature of the bath, coherence at long times can be retained; (b) the long-time asymptotic degree of coherence in the system is intertwined with the asymptotic difference in level populations; (c) the traditional population-relaxation and decoherence times, $T_1$ and $T_2$, lose their meaning when the system is in the presence of an external field, and are replaced by more general overall timescales; (d) increasing the field strength, quantified by the Rabi frequency, $\Omega$, increases the rate of decoherence rather than reducing it, as one might expect; and (e) maximum asymptotic coherence is reached when the system parameters satisfy $\Omega^2 = 1/(T_1 T_2)$. \\ ( http://arXiv.org/abs/quant-ph/0604082 , 112kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604330 Date: Thu, 13 Apr 2006 01:52:19 GMT (150kb) Title: Bragg scattering of Cooper pairs in an ultra-cold Fermi gas Authors: K. J. Challis, R. J. Ballagh, and C. W. Gardiner Subj-class: Other \\ We present a theoretical treatment of Bragg scattering of a degenerate Fermi gas, based on the time-dependent Bogoliubov de Gennes equations. Numerical solutions show that, in addition to the expected single-particle Bragg scattering, correlated scattering of atom pairs occurs via a grating formed in the pair potential. The correlated-pair Bragg scattering has a sharp frequency threshold, beyond which the scattered pairs form a spherical shell in momentum space that is centered at half the usual Bragg momentum transfer. We develop an analytic model that explains key features of correlated-pair Bragg scattering. \\ ( http://arXiv.org/abs/cond-mat/0604330 , 150kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604339 Date: Thu, 13 Apr 2006 13:05:11 GMT (586kb) Title: Generic Phase Diagram of Fermion Superfluids with Population Imbalance Authors: K. Machida, T. Mizushima, M. Ichioka Comments: 5 pages, 5 figuess Subj-class: Superconductivity \\ It is shown by microscopic calculations for trapped imbalanced Fermi superfluids that the gap function has always sign changes, or is Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state like, up to a critical imbalance $P_c$ at temperature T=0. A phase diagram is constructed in $T$ vs $P$, where the BCS state without sign change is stable only at $T \neq 0$. We reproduce the observed bimodality in the density profile to identify its origin and evaluate $P_c$ as functions of $T$ and the coupling strength. These dependencies match with the recent experiments. \\ ( http://arXiv.org/abs/cond-mat/0604339 , 586kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604348 Date: Thu, 13 Apr 2006 15:55:58 GMT (252kb) Title: Realization of a single Josephson junction for Bose-Einstein condensates Authors: Rudolf Gati, Micheal Albiez, Jonas Foelling, Boerge Hemmerling, Markus K. Oberthaler Subj-class: Other Journal-ref: Appl. Phys. B 82, 207 (2006) DOI: 10.1007/s00340-005-2059-z \\ We report on the realization of a double-well potential for Rubidium-87 Bose-Einstein condensates. The experimental setup allows the investigation of two different dynamical phenomena known for this system - Josephson oscillations and self-trapping. We give a detailed discussion of the experimental setup and the methods used for calibrating the relevant parameters. We compare our experimental findings with the predictions of an extended two-mode model and find quantitative agreement. \\ ( http://arXiv.org/abs/cond-mat/0604348 , 252kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604357 Date: Thu, 13 Apr 2006 18:19:25 GMT (10kb) Title: Anyon-fermion mapping and applications to ultracold gases in tight waveguides Authors: M. D. Girardeau Comments: 4 pages, revtex4, submitted to Phys. Rev. Lett Subj-class: Soft Condensed Matter \\ The Fermi-Bose mapping method for one-dimensional (1D) Bose and Fermi gases with zero-range interactions is generalized to an anyon-fermion mapping and applied to exact solution of several models of ultracold gases with anyonic exchange symmetry in tight waveguides: anyonic Calogero-Sutherland model, anyons with point hard core interaction ("anyonic TG gas"), and spin-aligned anyon gas with infinite zero-range odd-wave attractions ("anyonic FTG gas"). It is proved that for even $N\ge 4$ there are states of the anyonic FTG gas on a ring, with anyonic phase slips which are odd integral multiples of $\pi/(N-1)$, of energy lower than that of the corresponding fermionic ground state. A generalization to a spinor Fermi gas state with anyonic symmetry under purely spatial exchange enables energy lowering by the same mechanism. \\ ( http://arXiv.org/abs/cond-mat/0604357 , 10kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511647 replaced with revised version Thu, 13 Apr 2006 08:44:03 GMT (21kb) Title: Thermodynamic properties of a trapped Bose gas : A diffusion Monte Carlo study Authors: S Datta Comments: 9 pages, 12 figures Subj-class: Statistical Mechanics \\ ( http://arXiv.org/abs/cond-mat/0511647 , 21kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0601147 replaced with revised version Thu, 13 Apr 2006 12:23:49 GMT (888kb) Title: LOFF Pairing vs. Breached Pairing in Asymmetric Fermion Superfluids Authors: Lianyi He, Meng Jin and Pengfei Zhuang Comments: 11 pages, 13 figures, error corrected, numerical results for different regularization shemes checked. Submitted for publication Subj-class: Superconductivity \\ ( http://arXiv.org/abs/cond-mat/0601147 , 888kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0602483 replaced with revised version Thu, 13 Apr 2006 02:42:23 GMT (83kb) Title: Ground state properties of finite ultracold Bose gases in a hard-wall trap Authors: Yajiang Hao, Yunbo Zhang, J.-Q. Liang and Shu Chen Comments: 7 pages, 6 figures, significant extensions made and a new figure added Subj-class: Strongly Correlated Electrons \\ ( http://arXiv.org/abs/cond-mat/0602483 , 83kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603754 replaced with revised version Thu, 13 Apr 2006 04:46:53 GMT (17kb) Title: Bose-Einstein Condensation with Entangled Order Parameter Authors: Yu Shi, Qian Niu Comments: V1: 5 pages, 4 figures. Accepted by Phys. Rev. Lett.; V2: A couple of very minor typos corrected, published Subj-class: Other Journal-ref: Phys. Rev. Lett. 96, 140401 (2006) DOI: 10.1103/PhysRevLett.96.140401 \\ ( http://arXiv.org/abs/cond-mat/0603754 , 17kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604097 Date: Thu, 13 Apr 2006 12:47:03 GMT (117kb) Title: Quantum criticality in a generalized Dicke model Authors: Y. Li, Z. D. Wang, and C. P. Sun Comments: 4 pages, 3 figures \\ We employ a generalized Dicke model to study theoretically the quantum criticality of an extended two-level atomic ensemble interacting with a single-mode quantized light field. Effective Hamiltonians are derived and digonalized to investigate numerically their eigenfrequencies for different quantum phases in the system. Based on the analysis of the eigenfrequencies, an intriguing quantum phase transition from a normal phase to a super-radiant phase is revealed clearly, which is quite different from that observed with a standard Dicke model. \\ ( http://arXiv.org/abs/quant-ph/0604097 , 117kb) ------------------------------------------------------------------------------ \\ Paper (*cross-listing*): cond-mat/0603754 Date: Tue, 28 Mar 2006 12:43:54 GMT (17kb) Date (revised v2): Thu, 13 Apr 2006 04:46:53 GMT (17kb) Title: Bose-Einstein Condensation with Entangled Order Parameter Authors: Yu Shi, Qian Niu Comments: V1: 5 pages, 4 figures. Accepted by Phys. Rev. Lett.; V2: A couple of very minor typos corrected, published Subj-class: Other Journal-ref: Phys. Rev. Lett. 96, 140401 (2006) DOI: 10.1103/PhysRevLett.96.140401 \\ We propose a practically accessible non-mean-field ground state of Bose-Einstein condensation (BEC), which occurs in an interspecies two-particle entangled state, and is thus described by an entangled order parameter. A suitably defined entanglement entropy is used as the characterization of the non-mean-field nature, and is found to persist in a wide parameter regime. The interspecies entanglement leads to novel interference terms in the dynamical equations governing the single particle orbital wavefunctions. Experimental feasibility and several methods of probe are discussed. We urge the study of multi-channel scattering between different species of atoms. \\ ( http://arXiv.org/abs/cond-mat/0603754 , 17kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0604371 Date: Fri, 14 Apr 2006 13:03:58 GMT (32kb) Title: The origin of phase in the interference of Bose-Einstein condensates Authors: W. J. Mullin, R. Krotkov, and F. Lalo\"{e} Comments: 22 pages 4 figures Subj-class: Other; Statistical Mechanics \\ We consider the interference of two overlapping ideal Bose-Einstein condensates. The usual description of this phenomenon involves the introduction of a so-called condensate wave functions having a definite phase. We investigate the origin of this phase and the theoretical basis of treating interference. It is possible to construct a phase state, for which the particle number is uncertain, but phase is known. However, how one would prepare such a state before an experiment is not obvious. We show that a phase can also arise from experiments using condensates in Fock states, that is, having known particle numbers. Analysis of measurements in such states also gives us a prescription for preparing phase states. The connection of this procedure to questions of ``spontaneously broken gauge symmetry'' and to ``hidden variables'' is mentioned. \\ ( http://arXiv.org/abs/cond-mat/0604371 , 32kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0601604 replaced with revised version Fri, 14 Apr 2006 09:34:11 GMT (187kb) Title: Thermal fluctuations of vortex clusters in quasi two-dimensional Bose-Einstein condensate Authors: W. V. Pogosov and K. Machida Comments: 8 pages, 4 figures Subj-class: Statistical Mechanics; Other \\ ( http://arXiv.org/abs/cond-mat/0601604 , 187kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604103 Date: Fri, 14 Apr 2006 05:50:18 GMT (130kb) Title: A novel interferometer to beat the standard quantum limit using optical transverse modes in multimode waveguide Authors: Jian Fu Comments: 9 pages, 5 figures \\ We propose a novel interferometer by using optical transverse modes in multimode waveguide that can beat the standard quantum limit. In the scheme, the classical simulation of $N$-partical quantum entangled states is generated by using $N$ independent classical fields and linear optical elements. Similar to the quantum-enhanced measurements, the classical simulation can also achieve $\sqrt{N}$ enhancement over the precision of the measurement $N$ times for independent fields. Due to only using classical fields and linear optical elements, the scheme can be realized much more easily. \\ ( http://arXiv.org/abs/quant-ph/0604103 , 130kb) ------------------------------------------------------------------------------ \\ Paper (*cross-listing*): nlin.PS/0504061 Date: Fri, 29 Apr 2005 11:06:48 GMT (39kb) Date (revised v2): Wed, 25 Jan 2006 13:22:53 GMT (69kb) Title: Spatial dispersive shock waves generated in supersonic flow of Bose-Einstein condensate past slender body Authors: G.A. El and A.M. Kamchatnov Comments: 10 pages, revised version with additions and corrections Subj-class: Pattern Formation and Solitons; Soft Condensed Matter Journal-ref: Phys. Lett. A 350, 192-196 (2006) \\ Supersonic flow of Bose-Einstein condensate past macroscopic obstacles is studied theoretically. It is shown that in the case of large obstacles the Cherenkov cone transforms into a stationary spatial shock wave which consists of a number of spatial dark solitons. Analytical theory is developed for the case of obstacles having a form of a slender body. This theory explains qualitatively the properties of such shocks observed in recent experiments on nonlinear dynamics of condensates of dilute alkali gases. \\ ( http://arXiv.org/abs/nlin/0504061 , 69kb) ------------------------------------------------------------------------------ \\ Paper (*cross-listing*): nucl-th/0604028 Date: Wed, 12 Apr 2006 12:47:16 GMT (108kb) Title: Two-body correlation functions in nuclear matter with $np$ condensate Authors: A.A. Isayev Comments: Prepared with RevTeX4, 5p., 4 figures Subj-class: Nuclear Theory; Other \\ The density, spin and isospin correlation functions in nuclear matter with a neutron-proton ($np$) condensate are calculated to study the possible signatures of the BEC-BCS crossover in the low-density region. It is shown that the criterion of the crossover (Phys. Rev. Lett. {\bf 95}, 090402 (2005)), consisting in the change of the sign of the density correlation function at low momentum transfer, fails to describe correctly the density-driven BEC-BCS transition at finite isospin asymmetry or finite temperature. As an unambiguous signature of the BEC-BCS transition, there can be used the presence (BCS regime) or absence (BEC regime) of the singularity in the momentum distribution of the quasiparticle density of states. \\ ( http://arXiv.org/abs/nucl-th/0604028 , 108kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511514 replaced with revised version Mon, 17 Apr 2006 13:22:45 GMT (30kb) Title: Effect of the Zero-Mode on the Response of a Trapped Bose-Condensed Gas Authors: Makoto Mine, Tomoi Koide, Masahiko Okumura, Yoshiya Yamanaka Comments: 18 pages, 3 figures Subj-class: Other \\ ( http://arXiv.org/abs/cond-mat/0511514 , 30kb) ------------------------------------------------------------------------------ \\ Paper (*cross-listing*): nlin.PS/0507025 replaced with revised version Sun, 16 Apr 2006 23:52:53 GMT (906kb) Title: Feshbach Resonance Management of Bose-Einstein Condensates in Optical Lattices Authors: Mason A. Porter, Marina Chugunova, and Dmitry E. Pelinovsky Comments: 8 pages, 5 figures (1 with six parts, 4 with two parts), submitted to Physical Review E Subj-class: Pattern Formation and Solitons; Other; Atomic Physics; Dynamical Systems \\ ( http://arXiv.org/abs/nlin/0507025 , 906kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0604110 Date: Sat, 15 Apr 2006 23:12:16 GMT (174kb) Title: Observation of high-order quantum resonances in the kicked rotor Authors: J.F. Kanem, S. Maneshi, M. Partlow, M. Spanner and A.M. Steinberg \\ Quantum resonances in the kicked rotor are characterized by a dramatically increased energy absorption rate, in stark contrast to the momentum localization generally observed. These resonances occur when the scaled Planck's constant hbar=(r/s)*4pi, for any integers r and s. However only the hbar=r*2pi resonances are easily observable. We have observed high-order quantum resonances (s>2) utilizing a sample of low temperature, non-condensed atoms and a pulsed optical standing wave. Resonances are observed for hbar=(r/16)*4pi r=2-6. Quantum numerical simulations suggest that our observation of high-order resonances indicates a larger coherence length than expected from an initially thermal atomic sample. \\ ( http://arXiv.org/abs/quant-ph/0604110 , 174kb) ------------------------------------------------------------------------------Received on Tue Apr 18 2006 - 15:12:42 EST
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