8,903 research outputs found
Influence of Cooper pairing on the inelastic processes in a gas of Fermi atoms
Correlation properties in ultracold Fermi gas with negative scattering length
and its impact on the three-body recombination is analyzed. We find that Cooper
pairing enhances the recombination rate in contrast to the decrease of this
rate accompanying Bose-Einstein condensation in a Bose gas. This trend is
characteristic for all interval of temperatures T<Tc
Supercurrent Stability in a Quasi-1D Weakly Interacting Bose Gas
We discuss a possibility of observing superfluid phenomena in a quasi-1D
weakly interacting Bose gas at finite temperatures. The weakness of interaction
in combination with generic properties of 1D liquids can result in a situation
when relaxational time of supercurrent is essentially larger than the time of
experimental observation, and the behavior of the system is indistinguishable
from that of a genuine superfluid.Comment: Revtex, 4 pages, no figures; Submitted to Phys. Rev. A (Brief
Reports
BCS - BEC crossover and quantum hydrodynamics in p-wave superfluids with a symmetry of the A1 - phase
We solve the Leggett equations for the BCS - BEC crossover in the three
dimension resonance p-wave superfluid with the symmetry of the A1 - phase. We
calculate the sound velocity, the normal density, and the specific heat for the
BCS-domain (\mu > 0), BEC-domain (\mu < 0), and close to important point \mu =
0 in 100% polarized case. We find the indications of quantum phase - transition
close to the point \mu(T = 0) = 0. Deep in the BCS and BEC-domains the
crossover ideas of Leggett and Nozieres, Schmitt-Rink work pretty well. We
discuss the spectrum of orbital waves, the paradox of intrinsic angular
momentum and complicated problem of chiral anomaly in the BCS A1 - phase at T =
0. We present two different approaches to a chiral anomaly: one based on
supersymmetric hydrodynamics, another one on the formal analogy with the Dirac
equation in quantum electrodynamics. We evaluate the damping of nodal fermions
due to different decay processes in superclean case at T = 0 and find that we
are in a ballistic regime \omega\tau >> 1. We propose to use aerogel or
nonmagnetic impurities to reach hydrodynamic regime \omega\tau<< 1 at T = 0. We
discuss the concept of the spectral flow and exact cancellations between
time-derivatives of anomalous and quasiparticle currents in the equation for
the total linear momentum conservation. We propose to derive and solve the
kinetic equation for the nodal quasiparticles both in the hydrodynamic and in
the ballistic regimes to demonstrate this cancellation explicitly. We briefly
discuss the role of the other residual interactions different from damping and
invite experimentalists to measure the spectrum and damping of orbital waves in
A-phase of 3He at low temperatures.Comment: 14 pages, 10 figure
Critical Dynamics of a Two-dimensional Superfluid near a Non-Thermal Fixed Point
Critical dynamics of an ultracold Bose gas far from equilibrium is studied in
two spatial dimensions. Superfluid turbulence is created by quenching the
equilibrium state close to zero temperature. Instead of immediately
re-thermalizing, the system approaches a meta-stable transient state,
characterized as a non-thermal fixed point. A focus is set on the vortex
density and vortex-antivortex correlations which characterize the evolution
towards the non-thermal fixed point and the departure to final
(quasi-)condensation. Two distinct power-law regimes in the vortex-density
decay are found and discussed in terms of a vortex binding-unbinding transition
and a kinetic description of vortex scattering. A possible relation to decaying
turbulence in classical fluids is pointed out. By comparing the results to
equilibrium studies of a two-dimensional Bose gas, an intuitive understanding
of the location of the non-thermal fixed point in a reduced phase space is
developed.Comment: 11 pages, 13 figures; PRA versio
Finite temperature correlations and density profiles of an inhomogeneous interacting 1D Bose gas
We calculate the density profiles and density correlation functions of the
one-dimensional Bose gas in a harmonic trap, using the exact finite-temperature
solutions for the uniform case, and applying a local density approximation. The
results are valid for a trapping potential which is slowly varying relative to
a correlation length. They allow a direct experimental test of the transition
from the weak coupling Gross-Pitaevskii regime to the strong coupling,
'fermionic' Tonks-Girardeau regime. We also calculate the average two-particle
correlation which characterizes the bulk properties of the sample, and find
that it can be well approximated by the value of the local pair correlation in
the trap center.Comment: Final published version; updated references; 19 pages, 12 figure
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