23,374 research outputs found
Reversible and irreversible evolution of a condensed bosonic gas
We have formulated a kinetic theory for a condensed atomic gas in a trap,
i.e., a generalized Gross-Pitaevskii equation, as well as a quantum-Boltzmann
equation for the normal and anomalous fluctuations [R. Walser et al., Phys.
Rev. A, 59, 3878 (1999)]. In this article, the theory is applied to the case of
an isotropic configuration and we present numerical and analytical results for
the reversible real-time propagation, as well as irreversible evolution towards
equilibrium.Comment: 15 pages RevTeX, 8 figures, reviewed PRA resubmissio
Quantum Kinetic Theory for a Condensed Bosonic Gas
We present a kinetic theory for Bose-Einstein condensation of a weakly
interacting atomic gas in a trap. Starting from first principles, we establish
a Markovian kinetic description for the evolution towards equilibrium. In
particular, we obtain a set of self-consistent master equations for mean
fields, normal densities, and anomalous fluctuations. These kinetic equations
generalize the Gross-Pitaevskii mean-field equations, and merge them
consistently with a quantum-Boltzmann equation approach.Comment: 15 pages, no figures; reviewed version; to be published in PR
Direct combination: a new user interaction principle for mobile and ubiquitous HCI
Direct Combination (DC) is a recently introduced user interaction principle. The principle (previously applied to desktop computing) can greatly reduce the degree of search, time, and attention required to operate user interfaces. We argue that Direct Combination applies particularly aptly to mobile computing devices, given appropriate interaction techniques, examples of which are presented here. The reduction in search afforded to users can be applied to address several issues in mobile and ubiquitous user interaction including: limited feedback bandwidth; minimal attention situations; and the need for ad-hoc spontaneous interoperation and dynamic reconfiguration of multiple devices. When Direct Combination is extended and adapted to fit the demands of mobile and ubiquitous HCI, we refer to it as Ambient Combination (AC) . Direct Combination allows the user to exploit objects in the environment to narrow down the range of interactions that need be considered (by system and user). When the DC technique of pairwise or n-fold combination is applicable, it can greatly lessen the demands on users for memorisation and interface navigation. Direct Combination also appears to offers a new way of applying context-aware information. In this paper, we present Direct Combination as applied ambiently through a series of interaction scenarios, using an implemented prototype system
The deconfinement phase transition in Yang-Mills theory with general Lie group G
We present numerical results for the deconfinement phase transition in Sp(2)
and Sp(3) Yang-Mills theories in (2+1)-D and (3+1)-D. We then make a conjecture
on the order of this phase transition in Yang-Mills theories with general Lie
groups G = SU(N), SO(N), Sp(N) and with exceptional groups G = G(2), F(4),
E(6), E(7), E(8).Comment: Lattice2003(Topology and Confinement), 3 pages, 3 figure
When is the deconfinement phase transition universal?
Pure Yang-Mills theory has a finite-temperature phase transition, separating
the confined and deconfined bulk phases. Svetitsky and Yaffe conjectured that
if this phase transition is of second order, it belongs to the universality
class of transitions for particular scalar field theories in one lower
dimension. We examine Yang-Mills theory with the symplectic gauge groups Sp(N).
We find new evidence supporting the Svetitsky-Yaffe conjecture and make our own
conjecture as to which gauge theories have a universal second order
deconfinement phase transition.Comment: 5 pages, 4 figures; Contribution to Confinement 2003, Tokyo, Japan,
July 21-24, 200
Thermodynamics of Multi-Component Fermi Vapors
We study the thermodynamical properties of Fermi vapors confined in a
harmonic external potential. In the case of the ideal Fermi gas, we compare
exact density profiles with their semiclassical approximation in the conditions
of recent experiments. Then, we consider the phase-separation of a
multi-component Fermi vapor. In particular, we analyze the phase-separation as
a function of temperature, number of particles and scattering length. Finally,
we discuss the effect of rotation on the stability and thermodynamics of the
trapped vapors.Comment: 15 pages, 5 figures, to be published in J. Phys. B (Atom. Mol.) as a
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