9,019 research outputs found
Novel vortex structures in dipolar condensates
We investigate the properties of single vortices and of vortex lattice in a
rotating dipolar condensate. We show that vortices in this system possess many
novel features induced by the long-range anisotropic dipolar interaction
between particles. For example, when the dipoles are polarized along the
rotation axis, vortices may display a crater-like structure; when dipoles are
polarized orthogonal to the rotation axis, vortex cores takes an elliptical
shape and the vortex lattice no longer possesses hexagonal symmetry.Comment: 4 pages, 5 figure
User's guide to four-body and three-body trajectory optimization programs
A collection of computer programs and subroutines written in FORTRAN to calculate 4-body (sun-earth-moon-space) and 3-body (earth-moon-space) optimal trajectories is presented. The programs incorporate a variable step integration technique and a quadrature formula to correct single step errors. The programs provide capability to solve initial value problem, two point boundary value problem of a transfer from a given initial position to a given final position in fixed time, optimal 2-impulse transfer from an earth parking orbit of given inclination to a given final position and velocity in fixed time and optimal 3-impulse transfer from a given position to a given final position and velocity in fixed time
Phase space deformation of a trapped dipolar Fermi gas
We consider a system of quantum degenerate spin polarized fermions in a
harmonic trap at zero temperature, interacting via dipole-dipole forces. We
introduce a variational Wigner function to describe the deformation and
compression of the Fermi gas in phase space and use it to examine the stability
of the system. We emphasize the important roles played by the Fock exchange
term of the dipolar interaction which results in a non-spherical Fermi surface.Comment: 5 pages, 5 figure
A consistent description of kinetic equation with triangle anomaly
We provide a consistent description of the kinetic equation with triangle
anomaly which is compatible with the entropy principle of the second law of
thermodynamics and the charge/energy-momentum conservation equations. In
general an anomalous source term is necessary to ensure that the equations for
the charge and energy-momentum conservation are satisfied and that the
correction terms of distribution functions are compatible to these equations.
The constraining equations from the entropy principle are derived for the
anomaly-induced leading order corrections to the particle distribution
functions. The correction terms can be determined for minimum number of unknown
coefficients in one charge and two charge cases by solving the constraining
equations.Comment: RevTex 4, 11 pages; With minor changes: typos are corrected and one
reference is added. Accepted version to PR
Fermi liquid features of the one-dimensional Luttinger liquid
We show that the one-dimensional (1D) electron systems can also be described
by Landau's phenomenological Fermi-liquid theory. Most of the known results
derived from the Luttinger-liquid theory can be retrieved from the 1D
Fermi-liquid theory.
Exact correspondence between the Landau parameters and Haldane parameters is
established. The exponents of the dynamical correlation functions and the
impurity problem are also discussed based on the finite size corrections of
elementary excitations with the predictions of the conformal field theory,
which provides a bridge between the 1D Fermi-liquid and the Luttinger liquid.Comment: RevTeX, 5 pages, published versio
Making vortices in dipolar spinor condensates via rapid adiabatic passage
We propose to the create vortices in spin-1 condensates via magnetic
dipole-dipole interaction. Starting with a polarized condensate prepared under
large axial magnetic field, we show that by gradually inverting the field,
population transfer among different spin states can be realized in a controlled
manner. Under optimal condition, we generate a doubly quantized vortex state
containing nearly all atoms in the condensate. The resulting vortex state is a
direct manifestation of the dipole-dipole interaction and spin textures in
spinor condensates. We also point out that the whole process can be
qualitatively described by a simple rapid adiabatic passage model.Comment: 4 pages, 4 figure
Q -permutable subgroups of finite groups
A subgroup H of a group G is called Q-permutable in G if there exists a subgroup B of G such that (1) G=HB and (2) if H1 is a maximal subgroup of H containing HQG, then H1B=BH1<G, where HQG is the largest permutable subgroup of G contained in H. In this paper we prove that: Let F be a saturated formation containing U and G be a group with a normal subgroup H such that G/H∈F. If every maximal subgroup of every noncyclic Sylow subgroup of F∗(H) having no supersolvable supplement in G is Q-permutable in G, then G∈F.Пiдгрупу H групи G називають Q-переставною в G, якщо iснує пiдгрупа B групи G така, що: 1) G=HB та 2) якщо H1 — максимальна пiдгрупа H, що мiстить HQG, то H1B=BH1<G, де HQG є найбiльшою переставною пiдгрупою G, що мiститься в H. У цiй роботi доведено наступне твердження. Нехай F — насичена формацiя, що мiстить U, а G — група з нормальною пiдгрупою H такою, що G/H∈F. Якщо кожна максимальна пiдгрупа кожної нециклiчної силовської пiдгрупи F∗(H), що не має надрозв’язного доповнення в G, є Q-переставною в G, то G∈F
Does stability of relativistic dissipative fluid dynamics imply causality?
We investigate the causality and stability of relativistic dissipative fluid
dynamics in the absence of conserved charges. We perform a linear stability
analysis in the rest frame of the fluid and find that the equations of
relativistic dissipative fluid dynamics are always stable. We then perform a
linear stability analysis in a Lorentz-boosted frame. Provided that the ratio
of the relaxation time for the shear stress tensor, , to the sound
attenuation length, , fulfills a certain
asymptotic causality condition, the equations of motion give rise to stable
solutions. Although the group velocity associated with perturbations may exceed
the velocity of light in a certain finite range of wavenumbers, we demonstrate
that this does not violate causality, as long as the asymptotic causality
condition is fulfilled. Finally, we compute the characteristic velocities and
show that they remain below the velocity of light if the ratio
fulfills the asymptotic causality condition.Comment: 30 pages, 10 figures
Self-trapping of a Fermi super-fluid in a double-well potential in the BEC-unitarity crossover
We derive a generalized Gross-Pitaevskii density-functional equation
appropriate to study the Bose-Einstein condensate (BEC) of dimers formed of
singlet spin-half Fermi pairs in the BEC-unitarity crossover while the
dimer-dimer scattering length changes from 0 to . Using an
effective one-dimensional form of this equation, we study the phenomenon of
dynamical self-trapping of a cigar-shaped Fermi super-fluid in the entire
BEC-unitarity crossover in a double-well potential. A simple two-mode model is
constructed to provide analytical insights. We also discuss the consequence of
our study on the self-trapping of an atomic BEC in a double-well potential.Comment: 10 pages, 9 figure
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