1,023 research outputs found
Exact results for a tunnel-coupled pair of trapped Bose-Einstein condensates
A model describing coherent quantum tunneling between two trapped
Bose-Einstein condensates is shown to admit an exact solution. The spectrum is
obtained by the algebraic Bethe ansatz. An asymptotic analysis of the Bethe
ansatz equations leads us to explicit expressions for the energies of the
ground and first excited states in the limit of {\it weak} tunneling and all
energies for {\it strong} tunneling. The results are used to extract the
asymptotic limits of the quantum fluctuations of the boson number difference
between the two Bose-Einstein condensates and to characterize the degree of
coherence in the system.Comment: 5 pages, RevTex, No figure
Hole Doping Dependence of the Coherence Length in Thin Films
By measuring the field and temperature dependence of magnetization on
systematically doped thin films, the critical current
density and the collective pinning energy are determined in
single vortex creep regime. Together with the published data of superfluid
density, condensation energy and anisotropy, for the first time we derive the
doping dependence of the coherence length or vortex core size in wide doping
regime directly from the low temperature data. It is found that the coherence
length drops in the underdoped region and increases in the overdoped side with
the increase of hole concentration. The result in underdoped region clearly
deviates from what expected by the pre-formed pairing model if one simply
associates the pseudogap with the upper-critical field.Comment: 4 pages, 4 figure
Dynamical Properties of Multi-Armed Global Spirals in Rayleigh-Benard Convection
Explicit formulas for the rotation frequency and the long-wavenumber
diffusion coefficients of global spirals with arms in Rayleigh-Benard
convection are obtained. Global spirals and parallel rolls share exactly the
same Eckhaus, zigzag and skewed-varicose instability boundaries. Global spirals
seem not to have a characteristic frequency or a typical size ,
but their product is a constant under given experimental
conditions. The ratio of the radii of any two dislocations (,
) inside a multi-armed spiral is also predicted to be constant. Some of
these results have been tested by our numerical work.Comment: To appear in Phys. Rev. E as Rapid Communication
Quantum Criticality of 1D Attractive Fermi Gas
We obtain an analytical equation of state for one-dimensional strongly
attractive Fermi gas for all parameter regime in current experiments. From the
equation of state we derive universal scaling functions that control whole
thermodynamical properties in quantum critical regimes and illustrate physical
origin of quantum criticality. It turns out that the critical properties of the
system are described by these of free fermions and those of mixtures of
fermions with mass and . We also show how these critical properties of
bulk systems can be revealed from the density profile of trapped Fermi gas at
finite temperatures and can be used to determine the T=0 phase boundaries
without any arbitrariness.Comment: extended version, 9 pages, 7 eps figures, corrections of few typo
Wilson Ratio of Fermi gases in One Dimension
We calculate the Wilson ratio of the one-dimensional Fermi gas with spin imbalance. The Wilson ratio of attractively interacting fermions is solely determined by the density stiffness and sound velocity of pairs and of excess fermions for the two-compone
Enhanced Orbital Degeneracy in Momentum Space for LaOFeAs
The Fermi surfaces (FS) of LaOFeAs (in =0 plane) consist of two
hole-type circles around point, which do not touch each other, and two
electron-type co-centered ellipses around M point, which are degenerate along
the M-X line. By first-principles calculations, here we show that additional
degeneracy exists for the two electron-type FS, and the crucial role of
F-doping and pressure is to enhance this orbital degeneracy. It is suggested
that the inter-orbital fluctuation is the key point to understand the
unconventional superconductivity in these materials.Comment: 4 pages, 5 figure
Single chargino production via gluon-gluon fusion in a supersymmetric theory with an explicit R-parity violation
We studied the production of single chargino
accompanied by lepton via gluon-gluon fusion at the LHC. The
numerical analysis of their production rates is carried out in the mSUGRA
scenario with some typical parameter sets. The results show that the cross
sections of the productions via gluon-gluon
collision are in the order of femto barn quantitatively at the
CERN LHC, and can be competitive with production mechanism via quark-antiquark
annihilation process.Comment: LaTex file, 18 pages, 4 EPS file
Lipschitz equivalence of subsets of self-conformal sets
We give sufficient conditions to guarantee that if two self-conformal sets E
and F have Lipschitz equivalent subsets of positive measure, then there is a
bilipschitz map of E into, or onto, F
One-dimensional multicomponent fermions with delta function interaction in strong and weak coupling limits: Two-component Fermi gas
The Fredholm equations for one-dimensional two-component Fermions with
repulsive and with attractive delta-function interactions are solved by an
asymptotic expansion for A) strong repulsion, B) weak repulsion, C) weak
attraction and D) strong attraction. Consequently, we obtain the first few
terms of the expansion of ground state energy for the Fermi gas with
polarization for these regimes. We also prove that the two sets of the Fredhom
equations for weakly repulsive and attractive interactions are identical as
long as the integration boundaries match each other between the two sides. Thus
the asymptotic expansions of the energies of the repulsive and attractive
Fermions are identical to all orders in this region. The identity of the
asymptotic expansions may not mean that the energy analytically connects.Comment: 2 figures, 10 page
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