5,766 research outputs found
Emergence of Topological and Strongly Correlated Ground States in trapped Rashba Spin-Orbit Coupled Bose Gases
We theoretically study an interacting few-body system of Rashba spin-orbit
coupled two-component Bose gases confined in a harmonic trapping potential. We
solve the interacting Hamiltonian at large Rashba coupling strengths using
Exact Diagonalization scheme, and obtain the ground state phase diagram for a
range of interatomic interactions and particle numbers. At small particle
numbers, we observe that the bosons condense to an array of topological states
with n+1/2 quantum angular momentum vortex configurations, where n = 0, 1, 2,
3... At large particle numbers, we observe two distinct regimes: at weaker
interaction strengths, we obtain ground states with topological and symmetry
properties that are consistent with mean-field theory computations; at stronger
interaction strengths, we report the emergence of strongly correlated ground
states.Comment: 14 pages, 9 figure
In vitro assembly of xenotropic murine leukemia virus-related virus CA-NC protein
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Probing anisotropic superfluidity of rashbons in atomic Fermi gases
Motivated by the prospect of realizing a Fermi gas of K atoms with a
synthetic non-Abelian gauge field, we investigate theoretically a strongly
interacting Fermi gas in the presence of a Rashba spin-orbit coupling. As the
two-fold spin degeneracy is lifted by spin-orbit interaction, bound pairs with
mixed singlet and triplet pairings (referred to as rashbons) emerge, leading to
an anisotropic superfluid. We show that this anisotropic superfluidity can be
probed via measuring the momentum distribution and single-particle spectral
function in a trapped atomic K cloud near a Feshbach resonance.Comment: 4 pages, 5 figure
Probing Majorana fermions in spin-orbit coupled atomic Fermi gases
We examine theoretically the visualization of Majorana fermions in a
two-dimensional trapped ultracold atomic Fermi gas with spin-orbit coupling. By
increasing an external Zeeman field, the trapped gas transits from
non-topological to topological superfluid, via a mixed phase in which both
types of superfluids coexist. We show that the zero-energy Majorana fermion,
supported by the topological superfluid and localized at the vortex core, is
clearly visible through (i) the core density and (ii) the local density of
states, which are readily measurable in experiment. We present a realistic
estimate on experimental parameters for ultracold K atoms.Comment: 4 pages, 4 figure
Gapless topological Fulde-Ferrell superfluidity induced by in-plane Zeeman field
Topological superfluids are recently discovered quantum matters that host
topologically protected gapless edge states known as Majorana fermions - exotic
quantum particles that act as their own anti-particles and obey non-Abelian
statistics. Their realizations are believed to lie at the heart of future
technologies such as fault-tolerant quantum computation. To date, the most
efficient scheme to create topological superfluids and Majorana fermions is
based on the Sau-Lutchyn-Tewari-Das Sarma model with a Rashba-type spin-orbit
coupling on the }\textbf{\textit{x-y}}\textbf{ plane and a large out-of-plane
(perpendicular) Zeeman field along the }\textbf{\textit{z}}\textbf{-direction.
Here we propose an alternative setup, where the topological superfluid phase is
driven by applying an in-plane Zeeman field. This scheme offers a number of new
features, notably Cooper pairings at finite centre-of-mass momentum (i.e.,
Fulde-Ferrell pairing) and gapless excitations in the bulk. As a result, a
novel gapless topological quantum matter with inhomogeneous pairing order
parameter appears. It features unidirected Majorana surface states at
boundaries, which propagate in the same direction and connect two Weyl nodes in
the bulk. We demonstrate the emergence of such an exotic topological matter and
the associated Majorana fermions in spin-orbit coupled atomic Fermi gases and
determine its parameter space. The implementation of our scheme in
semiconductor/superconductor heterostructures is briefly discussed.Comment: 8 pages, 5 figure
Universal impurity-induced bound state in topological superfluids
We predict a universal mid-gap bound state in topological superfluids,
induced by either non-magnetic or magnetic impurities in the strong scattering
limit. This universal state is similar to the lowest-energy Caroli-de
Gennes-Martricon bound state in a vortex core, but is bound to localized
impurities. We argue that the observation of such a universal bound state can
be a clear signature for identifying topological superfluids. We theoretically
examine our argument for a spin-orbit coupled ultracold atomic Fermi gas
trapped in a two-dimensional harmonic potential, by performing extensive
self-consistent calculations within the mean-field Bogoliubov-de Gennes theory.
A realistic scenario for observing universal bound state in ultracold K
atoms is proposed.Comment: 5 pages + 4 figures; published in PRL; see the relevant study in 1D:
Phys. Rev. A 87, 013622 (2013); see also the accompanying Physics Synopsis:
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.110.02040
Radio-frequency spectroscopy of weakly bound molecules in spin-orbit coupled atomic Fermi gases
We investigate theoretically radio-frequency spectroscopy of weakly bound
molecules in an ultracold spin-orbit-coupled atomic Fermi gas. We consider two
cases with either equal Rashba and Dresselhaus coupling or pure Rashba
coupling. The former system has been realized very recently at Shanxi
University [Wang et al., arXiv:1204.1887] and MIT [Cheuk et al.,
arXiv:1205.3483]. We predict realistic radio-frequency signals for revealing
the unique properties of anisotropic molecules formed by spin-orbit coupling.Comment: 11 pages, 7 figure
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