44,620 research outputs found
M-body Pure State Entanglement
The simple entanglement of N-body N-particle pure states is extended to the
more general M-body or M-body N-particle states where . Some new
features of the M-body N-particle pure states are discussed. An application of
the measure to quantify quantum correlations in a Bose-Einstien condensate
model is demonstrated.Comment: 9 pages, 2 figure
Exact solutions of an extended Bose-Hubbard model with E2 symmetry
An extended Bose-Hubbard (BH) model with number-dependent multi-site and
infinite-range hopping is proposed, which, similar to the original BH model,
describes a phase transition between the delocalized super-fluid (SF) phase and
localized Mott insulator (MI) phase. It is shown that this extended model with
local Euclidean E2 symmetry is exactly solvable when on-site local potential or
disorder is included, while the model without local potential or disorder is
quasi-exactly solvable, which means only a part of the excited states including
the ground state being exactly solvable. As applications of the exact solution
for the ground state, phase diagram of the model in 1D without local potential
and on-site disorder for filling factor rho = 1 with M = 6 sites and that with
M = 10 are obtained. The probabilities to detect n particles on a single site,
Pn, for n = 0, 1, 2 as functions of the control parameter U/t in these two
cases are also calculated. It is shown that the critical point in Pn and in the
entanglement measure is away from that of the SF-MI transition determined in
the phase analysis. It is also shown that the the model-independent
entanglement measure is related with Pn, which, therefore, may be practically
useful because Pn is measurable experimentally.Comment: 5 pages, 3 figures, LaTe
A simple entanglement measure for multipartite pure states
A simple entanglement measure for multipartite pure states is formulated
based on the partial entropy of a series of reduced density matrices. Use of
the proposed new measure to distinguish disentangled, partially entangled, and
maximally entangled multipartite pure states is illustrated.Comment: 8 pages LaTe
Suppression of low-energy Andreev states by a supercurrent in YBa_2Cu_3O_7-delta
We report a coherence-length scale phenomenon related to how the high-Tc
order parameter (OP) evolves under a directly-applied supercurrent. Scanning
tunneling spectroscopy was performed on current-carrying YBa_2Cu_3O_7-delta
thin-film strips at 4.2K. At current levels well below the theoretical
depairing limit, the low-energy Andreev states are suppressed by the
supercurrent, while the gap-like structures remain unchanged. We rule out the
likelihood of various extrinsic effects, and propose instead a model based on
phase fluctuations in the d-wave BTK formalism to explain the suppression. Our
results suggest that a supercurrent could weaken the local phase coherence
while preserving the pairing amplitude. Other possible scenarios which may
cause the observed phenomenon are also discussed.Comment: 6 pages, 4 figures, to appear in Physical Review
The induced representations of Brauer algebra and the Clebsch-Gordan coefficients of SO(n)
Induced representations of Brauer algebra from with are discussed. The induction coefficients
(IDCs) or the outer-product reduction coefficients (ORCs) of with up to a normalization factor are
derived by using the linear equation method. Weyl tableaus for the
corresponding Gel'fand basis of SO(n) are defined. The assimilation method for
obtaining CG coefficients of SO(n) in the Gel'fand basis for no modification
rule involved couplings from IDCs of Brauer algebra are proposed. Some
isoscalar factors of for the resulting irrep
with
$\sum\limits_{i=1}^{4}\lambda_{i}\leq .Comment: 48 pages latex, submitted to Journal of Phys.
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