3,723 research outputs found
Vortex structures and zero energy states in the BCS-to-BEC evolution of p-wave resonant Fermi gases
Multiply quantized vortices in the BCS-to-BEC evolution of p-wave resonant
Fermi gases are investigated theoretically. The vortex structure and the
low-energy quasiparticle states are discussed, based on the self-consistent
calculations of the Bogoliubov-de Gennes and gap equations. We reveal the
direct relation between the macroscopic structure of vortices, such as particle
densities, and the low-lying quasiparticle state. In addition, the net angular
momentum for multiply quantized vortices with a vorticity is found to
be expressed by a simple equation, which reflects the chirality of the Cooper
pairing. Hence, the observation of the particle density depletion and the
measurement of the angular momentum will provide the information on the
core-bound state and -wave superfluidity. Moreover, the details on the zero
energy Majorana state are discussed in the vicinity of the BCS-to-BEC
evolution. It is demonstrated numerically that the zero energy Majorana state
appears in the weak coupling BCS limit only when the vortex winding number is
odd. There exist the branches of the core bound states for a vortex
state with vorticity , whereas only one of them can be the zero energy.
This zero energy state vanishes at the BCS-BEC topological phase transition,
because of interference between the core-bound and edge-bound states.Comment: 15 pages, 9 figures, published versio
Coreless and singular vortex lattices in rotating spinor Bose-Einstein condensates
We theoretically investigate vortex-lattice phases of rotating spinor
Bose-Einstein condensates (BEC) with the ferromagnetic spin-interaction by
numerically solving the Gross-Pitaevskii equation. The spinor BEC under slow
rotation can sustain a rich variety of exotic vortices due to the
multi-component order parameters, such as the Mermin-Ho and Anderson-Toulouse
coreless vortices (the 2-dimensional skyrmion and meron) and the
non-axisymmetric vortices with the sifting vortex cores. Here, we present the
spin texture of various vortex-lattice states at higher rotation rates and in
the presence of the external magnetic field. In addition, the vortex phase
diagram is constructed in the plane by the total magnetization and the
external rotation frequency by comparing the free energies of possible
vortices. It is shown that the vortex phase diagram in a - plane may
be divided into two categories; (i) the coreless vortex lattice formed by the
several types of Mermin-Ho vortices and (ii) the vortex lattice filling in the
cores with the pure polar (antiferromagnetic) state. In particular, it is found
that the type-(ii) state forms the composite lattices of coreless and
polar-core vortices. The difference between the type-(i) and type-(ii) results
from the existence of the singularity of the spin textures, which may be
experimentally confirmed by the spin imaging within polarized light recently
proposed by Carusotto and Mueller. We also discussed on the stability of
triangular and square lattice states for rapidly rotating condensates.Comment: to be published in Phys. Rev.
Spin textures in condensates with large dipole moments
We have solved numerically the ground states of a Bose-Einstein condensate in
the presence of dipolar interparticle forces using a semiclassical approach.
Our motivation is to model, in particular, the spontaneous spin textures
emerging in quantum gases with large dipole moments, such as 52Cr or Dy
condensates, or ultracold gases consisting of polar molecules. For a
pancake-shaped harmonic (optical) potential, we present the ground state phase
diagram spanned by the strength of the nonlinear coupling and dipolar
interactions. In an elongated harmonic potential, we observe a novel helical
spin texture. The textures calculated according to the semiclassical model in
the absence of external polarizing fields are predominantly analogous to
previously reported results for a ferromagnetic F = 1 spinor Bose-Einstein
condensate, suggesting that the spin textures arising from the dipolar forces
are largely independent of the value of the quantum number F or the origin of
the dipolar interactions.Comment: 9 pages, 6 figure
Generic Phase Diagram of Fermion Superfluids with Population Imbalance
It is shown by microscopic calculations for trapped imbalanced Fermi
superfluids that the gap function has always sign changes, i.e., the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state like, up to a critical imbalance
, beyond which normal state becomes stable, at temperature T=0. A phase
diagram is constructed in vs , where the BCS state without sign change
is stable only at . We reproduce the observed bimodality in the
density profile to identify its origin and evaluate as functions of
and the coupling strength. These dependencies match with the recent
experiments.Comment: 5 pages, 5 figures, replaced by the version to appear in PR
Vortex structure in spinor F=2 Bose-Einstein condensates
Extended Gross-Pitaevskii equations for the rotating F=2 condensate in a
harmonic trap are solved both numerically and variationally using trial
functions for each component of the wave function. Axially-symmetric vortex
solutions are analyzed and energies of polar and cyclic states are calculated.
The equilibrium transitions between different phases with changing of the
magnetization are studied. We show that at high magnetization the ground state
of the system is determined by interaction in "density" channel, and at low
magnetization spin interactions play a dominant role. Although there are five
hyperfine states, all the particles are always condensed in one, two or three
states. Two novel types of vortex structures are also discussed.Comment: 6 pages, 3 figure
Relocation of active acetylcholinesterase to liposome-gel conjugate
ArticleJOURNAL OF COLLOID AND INTERFACE SCIENCE. 307(1): 296-299 (2007)journal articl
Quantum Numbers for Excitations of Bose-Einstein Condensates in 1D Optical Lattices
The excitation spectrum and the band structure of a Bose-Einstein condensate
in a periodic potential are investigated. Analyses within full 3D systems,
finite 1D systems, and ideal periodic 1D systems are compared. We find two
branches of excitations in the spectra of the finite 1D model. The band
structures for the first and (part of) the second band are compared between a
finite 1D and the fully periodic 1D systems, utilizing a new definition of a
effective wavenumber and a phase-slip number. The upper and lower edges of the
first gap coincide well between the two cases. The remaining difference is
explained by the existence of the two branches due to the finite-size effect.Comment: 5 pages, 9 figure
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