3,949 research outputs found
Coherent transport of matter waves
A transport theory for atomic matter waves in low-dimensional waveguides is
outlined. The thermal fluctuation spectrum of magnetic near fields leaking out
of metallic microstructures is estimated. The corresponding scattering rate for
paramagnetic atoms turns out to be quite large in micrometer-sized waveguides
(approx. 100/s). Analytical estimates for the heating and decoherence of a cold
atom cloud are given. We finally discuss numerical and analytical results for
the scattering from static potential imperfections and the ensuing spatial
diffusion process.Comment: 9 pages incl. 10 PostScript figures (.eps), LaTeX using Springer
style file svjour, submitted to Appl. Phys.
Two-time autocorrelation function in phase-ordering kinetics from local scale-invariance
The time-dependent scaling of the two-time autocorrelation function of spin
systems without disorder undergoing phase-ordering kinetics is considered. Its
form is shown to be determined by an extension of dynamical scaling to a local
scale-invariance which turns out to be a new version of conformal invariance.
The predicted autocorrelator is in agreement with Monte-Carlo data on the
autocorrelation function of the 2D kinetic Ising model with Glauber dynamics
quenched to a temperature below criticality.Comment: Latex2e, 7 pages with 2 figures, with epl macro, final from, to
appear in EP
On the feasibility of studying vortex noise in 2D superconductors with cold atoms
We investigate the feasibility of using ultracold neutral atoms trapped near
a thin superconductor to study vortex noise close to the
Kosterlitz-Thouless-Berezinskii transition temperature. Alkali atoms such as
rubidium probe the magnetic field produced by the vortices. We show that the
relaxation time of the Zeeman sublevel populations can be conveniently
adjusted to provide long observation times. We also show that the transverse
relaxation times for Zeeman coherences are ideal for studying the vortex
noise. We briefly consider the motion of atom clouds held close to the surface
as a method for monitoring the vortex motion.Comment: 4 pages, 1 figur
On the spectral distribution of photons between planar interfaces
Using a phenomenological approach to field quantization, an expression for
the Keldysh function of photons between two planar interfaces (Casimir
geometry) is found for any stationary quantum state of the two bodies. The case
of one interface sliding against the other is considered in detail
Thermal effects in the magnetic Casimir-Polder interaction
We investigate the magnetic dipole coupling between a metallic surface and an
atom in a thermal state, ground state and excited hyperine state. This
interaction results in a repulsive correction and - unlike the electrical
dipole contribution - depends sensitively on the Ohmic dissipation in the
material
Kinetics of the long-range spherical model
The kinetic spherical model with long-range interactions is studied after a
quench to or to . For the two-time response and correlation
functions of the order-parameter as well as for composite fields such as the
energy density, the ageing exponents and the corresponding scaling functions
are derived. The results are compared to the predictions which follow from
local scale-invariance.Comment: added "fluctuation-dissipation ratios"; fixed typo
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