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

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

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

Double-exchange model: phase separation versus canted spins

We study the competition between different possible ground states of the double-exchange model with strong ferromagnetic exchange interaction between itinerant electrons and local spins. Both for classical and quantum treatment of the local spins the homogeneous canted state is shown to be unstable against a phase separation. The conditions for the phase separation into the mixture of the antiferromagnetic and ferromagnetic/canted states are given. We also discuss another possible realization of the phase-separated state: ferromagnetic polarons embedded into an antiferromagnetic surrounding. The general picture of a percolated state, which emerges from these considerations, is discussed and compared with results of recent experiments on doped manganaties.Comment: 10 pages, revtex, modified text and 2 new figure

Stability and phase coherence of trapped 1D Bose gases

We discuss stability and phase coherence of 1D trapped Bose gases and find that inelastic decay processes, such as 3-body recombination, are suppressed in the strongly interacting (Tonks-Girardeau) and intermediate regimes. This is promising for achieving these regimes with a large number of particles. "Fermionization" of the system reduces the phase coherence length, and at T=0 the gas is fully phase coherent only deeply in the weakly interacting (Gross-Pitaevskii) regime.Comment: published versio