110 research outputs found
Multi-particle composites in density-imbalanced quantum fluids
We consider two-component one-dimensional quantum gases with density
imbalance. While generically such fluids are two-component Luttinger liquids,
we show that if the ratio of the densities is a rational number, p/q, and mass
asymmetry between components is sufficiently strong, one of the two eigenmodes
acquires a gap. The gapped phase corresponds to (algebraic) ordering of
(p+q)-particle composites. In particular, for attractive mixtures, this implies
that the superconducting correlations are destroyed. We illustrate our
predictions by numerical simulations of the fermionic Hubbard model with
hopping asymmetry.Comment: 4+ pages, 1 figure, published versio
Momentum relaxation of a mobile impurity in a one-dimensional quantum gas
We investigate the time evolution of the momentum of an impurity atom
injected into a degenerate Tonks-Girardeau gas. We establish that given an
initial momentum the impurity relaxes to a steady state with a
non-vanishing momentum The nature of the steady state is found to
depend drastically on whether the masses of the impurity and the host are equal
or not. This is due to multiple coherent scattering processes leading to a
resonant interaction between the impurity and the host in the case of equal
masses. The dependence of on remains non-trivial even in the
limit of vanishing interaction between the impurity and host particles. In this
limit is found explicitly
Luttinger liquid of trimers in Fermi gases with unequal masses
We investigate one dimensional attractive Fermi gases in spin-dependent
optical lattices. We show that three-body bound states - "trimers" - exist as
soon as the two tunneling rates are different. We calculate the binding energy
and the effective mass of a single trimer. We then show numerically that for
finite and commensurate densities an energy gap
appears, implying that the gas is a one-component Luttinger liquid of trimers
with suppressed superfluid ordering. The boundaries of this novel phase are
given. We discuss experimental situations to test our predictions.Comment: 4 pages, 4 figures. Final accepted versio
Thermodynamics of localized magnetic moments in a Dirac conductor
We show that the magnetic susceptibility of a dilute ensemble of magnetic
impurities in a conductor with a relativistic electronic spectrum is
non-analytic in the inverse tempertature at . We derive a general
theory of this effect and construct the high-temperature expansion for the
disorder averaged susceptibility to any order, convergent at all tempertaures
down to a possible ordering transition. When applied to Ising impurities on a
surface of a topological insulator, the proposed general theory agrees with
Monte Carlo simulations, and it allows us to find the critical temperature of
the ferromagnetic phase transition.Comment: 5 pages, 1 figure, 2 tables, RevTe
Thermodynamics of the 3D Hubbard model on approach to the Neel transition
We study the thermodynamic properties of the 3D Hubbard model for
temperatures down to the Neel temperature using cluster dynamical mean-field
theory. In particular we calculate the energy, entropy, density, double
occupancy and nearest-neighbor spin correlations as a function of chemical
potential, temperature and repulsion strength. To make contact with cold-gas
experiments, we also compute properties of the system subject to an external
trap in the local density approximation. We find that an entropy per particle
at is sufficient to achieve a Neel state in the
center of the trap, substantially higher than the entropy required in a
homogeneous system. Precursors to antiferromagnetism can clearly be observed in
nearest-neighbor spin correlators.Comment: 4 pages, 6 figure
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