6,378 research outputs found
Fermions in Deep Optical Lattice under p-wave Feshbach Resonance
We investigate theoretically the energy levels of two identical Fermions in a
harmonic potential well under p-wave Feshbach resonance. The magnetic fields
needed to affect the energy levels differ strongly among the levels, and they
can be at values far from the free space resonant field.Comment: 2 figure
Supercurrent and noise in point contact between two different superconductors
We show that, for a quantum point contact between two superconductors of
different gap magnitudes, Andreev bound states do not exist for certain phase
differences and gap ratios. Continuum states may dominate the transport, and
the supercurrent noise is qualitatively different from the case of equal gaps.Comment: to appear in PR
A dilute mixture of atoms and molecules
We study a dilute gas with two species of Fermionic atoms of unequal
concentrations, interacting via a short-range interaction with one deeply bound
state. We study the properties of this system under the mean-field
approximation. We obtain the effective interaction among the fermions and
bosons, and discuss the collective modes of the system.Comment: errors removed, reference not update
Local stability conditions for asymmetric Fermi superfluid
Two different local stability conditions for an asymmetric superfluid has
been discussed in the literature. We here consider the relations between them
Kinetic equation and magneto-conductance for Weyl metal in the clean limit
We discuss the semi-classical kinetic equation in the clean limit, with the
presence of Berry curvatures and magnetic field B, with the aim of applying to
Weyl semi-metals. Special attention is given to the conservation laws for the
collision integrals. It is found that the magneto-resistance second order in B
is in general negative, with or without Weyl points, though in the later case
it is in general much smaller.Comment: 10 page
Comment on "Classifying Novel Phases of Spinor Atoms"
Comment on "Classifying Novel Phases of Spinor Atoms", Phys. Rev. Lett. 97,
180412 (2006) by R. Barnett, A. Turner and E. DemlerComment: 1 pag
Anisotropic Fermi Superfluid via p-wave Feshbach Resonance
We investigate theoretically Fermionic superfluidity induced by Feshbach
resonance in the orbital p-wave channel. We show that, due to the dipole
interaction, the pairing is extremely anisotropic. When this dipole interaction
is relatively strong, the pairing has symmetry . When it is relatively
weak, it is of symmetry (up to a rotation about ,
here ). A phase transition between these two states can occur under
a change in the magnetic field or the density of the gas.Comment: 4 pages, 2 figure
Effects of voltage fluctuations on the current correlations in mesoscopic Y-shaped conductors
We study current fluctuations in a phase coherent Y-shaped conductor
connected to external leads and voltage probes. The voltage probes are taken to
have finite impedances and thus can cause voltage fluctuations in the circuit.
Applying the Keldysh formulation and a saddle point approximation appropriate
for slow fluctuations, we examine at zero temperature the feedback effects on
the current fluctuations due to the fluctuating voltages. We consider
mesoscopic Y-shaped conductors made of tunnel junctions and of diffusive wires.
Unlike two-terminal conductors, we find that for the Y-shaped conductors the
current moments in the presence of external impedances cannot be obtained from
simple rescaling of the bare moments already in the second moments. As a direct
consequence, we find that the cross correlation between the output terminals
can become positive due to the impedances in the circuit. We provide formulas
for the range of parameters that can cause positive cross correlations.Comment: Figures 2(b)(c) left out due to file size constraints (which,
however, can be requested from authors). Submitted to Phys. Rev.
Current response of a topological insulator to a static Zeeman field
We study the magnetoelectric coupling at the surface of a topological
insulator. We are in particular interested in the surface current induced by a
static Zeeman/exchange field. This surface current can be related to the
orbital magnetization of the system. For an insulator with zero Chern number,
the orbital magnetization is independent of the details at the boundary. With
the appearance of surface states in the topological insulator, it is not
immediately obvious if the response is not affected by the conditions at the
surface. We investigate this question using exact diagonalization to a lattice
model. By applying a time-reversal symmetry-breaking term near the boundary, no
matter if the surface states are gapped out, we still find no change in the
surface current. This arises from cancelations between Pauli and Van-Vleck
contributions between surface and bulk scattering states. We also show that the
surface current response is independent of the chemical potential when it is
within the bulk gap. Our results are consistent with the claim that orbital
magnetization is a bulk property
Mesoscopic p-wave superconductor near the phase transition temperature
We study the finite-size and boundary effects on a p-wave superconductor in a
mesoscopic rectangular sample using Ginzburg-Landau (GL) and quasi-classical
(QC) Green's function theory. Except for a square sample with parameters far
away from the isotropic weak-coupling limit, the ground state near the critical
temperature always prefers a time-reversal symmetric state, where the order
parameter can be represented by a real vector. For large aspect ratio, this
vector is parallel to the long side of the rectangle. Within a critical aspect
ratio, it has instead a vortex-like structure, vanishing at the sample center.Comment: Revised version published in Physical Review
- …