2,076 research outputs found
Thermodynamic Properties of Rashba Spin-Orbit-Coupled Fermi Gas
We investigate the thermodynamic properties of a superfluid Fermi gas subject
to Rashba spin-orbit coupling and effective Zeeman field. We adopt a T-matrix
scheme that takes beyond-mean-field effects, which are important for strongly
interacting systems, into account. We focus on the calculation of two important
quantities: the superfluid transition temperature and the isothermal
compressibility. Our calculation shows very distinct influences of the
out-of-plane and the in-plane Zeeman fields on the Fermi gas. We also confirm
that the in-plane Zeeman field induces a Fulde-Ferrell superfluid below the
critical temperature and an exotic finite-momentum pseudo-gap phase above the
critical temperature.Comment: 8 pages, 9 figure
Effective p-wave interaction and topological superfluids in s-wave quantum gases
P-wave interaction in cold atoms may give rise to exotic topological
superfluids. However, the realization of p-wave interaction in cold atom system
is experimentally challenging. Here we propose a simple scheme to synthesize
effective -wave interaction in conventional -wave interacting quantum
gases. The key idea is to load atoms into spin-dependent optical lattice
potential. Using two concrete examples involving spin-1/2 fermions, we show how
the original system can be mapped into a model describing spinless fermions
with nearest neighbor p-wave interaction, whose ground state can be a
topological superfluid that supports Majorana fermions under proper conditions.
Our proposal has the advantage that it does not require spin-orbit coupling or
loading atoms onto higher orbitals, which is the key in earlier proposals to
synthesize effective -wave interaction in -wave quantum gases, and may
provide a completely new route for realizing -wave topological superfluids.Comment: 5 pages, 4 figure
Field-induced topological pair-density wave states in a multilayer optical lattice
We study the superfluid phases of a Fermi gas in a multilayer optical lattice
system in the presence of out-of-plane Zeeman field, as well as spin-orbit (SO)
coupling. We show that the Zeeman field combined with the SO coupling leads to
exotic topological pair-density wave (PDW) phases in which different layers
possess different superfluid order parameters, even though each layer
experiences the same Zeeman field and the SO coupling. We elucidate the
mechanism of the emerging PDW phases, and characterize their topological
properties by calculating the associated Chern numbers.Comment: 7 pages, 6 figures, accepted by Phys. Rev.
Hartree-Fock-Bogoliubov Theory of Dipolar Fermi Gases
We construct a fully self-consistent Hartree-Fock-Bogoliubov theory that
describes a spinless Fermi gas with long-range interaction. We apply this
theory to a system of uniform dipolar fermionic polar molecules, which has
attracted much attention recently, due to rapid experimental progress in
achieving such systems. By calculating the anisotropic superfluid order
parameter, and the critical temperature , we show that, "hign "
superfluid can be achieved with a quite modest value of interaction strength
for polar molecules. In addition, we also show that the presence of the Fock
exchange interaction enhances superfluid pairing.Comment: 4.1 pages, 4 figure
Object Discovery From a Single Unlabeled Image by Mining Frequent Itemset With Multi-scale Features
TThe goal of our work is to discover dominant objects in a very general
setting where only a single unlabeled image is given. This is far more
challenge than typical co-localization or weakly-supervised localization tasks.
To tackle this problem, we propose a simple but effective pattern mining-based
method, called Object Location Mining (OLM), which exploits the advantages of
data mining and feature representation of pre-trained convolutional neural
networks (CNNs). Specifically, we first convert the feature maps from a
pre-trained CNN model into a set of transactions, and then discovers frequent
patterns from transaction database through pattern mining techniques. We
observe that those discovered patterns, i.e., co-occurrence highlighted
regions, typically hold appearance and spatial consistency. Motivated by this
observation, we can easily discover and localize possible objects by merging
relevant meaningful patterns. Extensive experiments on a variety of benchmarks
demonstrate that OLM achieves competitive localization performance compared
with the state-of-the-art methods. We also evaluate our approach compared with
unsupervised saliency detection methods and achieves competitive results on
seven benchmark datasets. Moreover, we conduct experiments on fine-grained
classification to show that our proposed method can locate the entire object
and parts accurately, which can benefit to improving the classification results
significantly
Artificial topological models based on a one-dimensional spin-dependent optical lattice
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