68,894 research outputs found
Calculating the relative entropy of entanglement
We extend Vedral and Plenio's theorem (theorem 3 in Phys. Rev. A 57, 1619) to
a more general case, and obtain the relative entropy of entanglement for a
class of mixed states, this result can also follow from Rains' theorem 9 in
Phys. Rev. A 60, 179.Comment: 2 pages, RevTex, an important reference adde
Theory of point contact spectroscopy in electron-doped cuprates
In the hole-doped -wave cuprate superconductor, due to the
midgap surface state (MSS), a zero bias conductance peak (ZBCP) is widely
observed in [110] interface point contact spectroscopy (PCS). However, ZBCP of
this geometry is rarely observed in the electron-doped cuprates, even though
their pairing symmetry is still likely the -wave. We argue
that this is due to the coexistence of antiferromagnetic (AF) and the
superconducting (SC) orders. Generalizing the Blonder-Tinkham-Klapwijk (BTK)
formula to include an AF coupling, it is shown explicitly that the MSS is
destroyed by the AF order. The calculated PCS is in good agreement with the
experiments.Comment: 5 pages, 2 figures. Replaced with published versio
Fractional statistic
We improve Haldane's formula which gives the number of configurations for
particles on states in a fractional statistic defined by the coupling
. Although nothing is changed in the thermodynamic limit, the new
formula makes sense for finite with integer and A
geometrical interpretation of fractional statistic is given in terms of
''composite particles''.Comment: flatex hald.tex, 3 files Submitted to: Phys. Rev.
Interplay between antiferromagnetic order and spin polarization in ferromagnetic metal/electron-doped cuprate superconductor junctions
Recently we proposed a theory of point-contact spectroscopy and argued that
the splitting of zero-bias conductance peak (ZBCP) in electron-doped cuprate
superconductor point-contact spectroscopy is due to the coexistence of
antiferromagnetic (AF) and d-wave superconducting orders [Phys. Rev. B {\bf
76}, 220504(R) (2007)]. Here we extend the theory to study the tunneling in the
ferromagnetic metal/electron-doped cuprate superconductor (FM/EDSC) junctions.
In addition to the AF order, the effects of spin polarization, Fermi-wave
vector mismatch (FWM) between the FM and EDSC regions, and effective barrier
are investigated. It is shown that there exits midgap surface state (MSS)
contribution to the conductance to which Andreev reflections are largely
modified due to the interplay between the exchange field of ferromagnetic metal
and the AF order in EDSC. Low-energy anomalous conductance enhancement can
occur which could further test the existence of AF order in EDSC. Finally, we
propose a more accurate formula in determining the spin polarization value in
combination with the point-contact conductance data.Comment: 9 pages, 8 figure
Phase separation of the Potts model in que square lattice
When the two dimensional q-color Potts model in the square lattice is
quenched at zero temperature with Glauber dynamics, the energy decreases in
time following an Allen-Cahn power law, and the system converges to a phase
with energy higher than the ground state energy after an arbitrary large time
when q>4. At low but finite temperature, it cesses to obey the power-law regime
and orders after a very long time, which increases with q, and before which it
performs a domain growth process which tends to be slower as q increases. We
briefly present and comment numerical results on the ordering at nonzero
temperature.Comment: 3 pages, 1 figure, proceedings of the "International Workshop on
Complex sytems", June 2006 in Santander (Spain
Twisted SUSY Invariant Formulation of Chern-Simons Gauge Theory on a Lattice
We propose a twisted SUSY invariant formulation of Chern-Simons theory on a
Euclidean three dimensional lattice. The SUSY algebra to be realized on the
lattice is the N=4 D=3 twisted algebra that was recently proposed by D'Adda et
al.. In order to keep the manifest anti-hermiticity of the action, we introduce
oppositely oriented supercharges. Accordingly, the naive continuum limit of the
action formally corresponds to the Landau gauge fixed version of Chern-Simons
theory with complex gauge group which was originally proposed by Witten. We
also show that the resulting action consists of parity even and odd parts with
different coefficients.Comment: 22 pages, 5 figures; v2,v3 added references, v4 added two paragraphs
and one figure in the summar
`Composite particles' and the eigenstates of Calogero-Sutherland and Ruijsenaars-Schneider
We establish a one-to-one correspondance between the ''composite particles''
with particles and the Young tableaux with at most rows. We apply this
correspondance to the models of Calogero-Sutherland and Ruijsenaars-Schneider
and we obtain a momentum space representation of the ''composite particles'' in
terms of creation operators attached to the Young tableaux. Using the technique
of bosonisation, we obtain a position space representation of the ''composite
particles'' in terms of products of vertex operators. In the special case where
the ''composite particles'' are bosons and if we add one extra quasiparticle or
quasihole, we construct the ground state wave functions corresponding to the
Jain series of the fractional quantum Hall effect.Comment: latex calcomp2.tex, 5 files, 30 pages [SPhT-T99/080], submitted to J.
Math. Phy
Exclusonic Quasiparticles and Thermodynamics of Fractional Quantum Hall Liquids
Quasielectrons and quasiholes in the fractional quantum Hall liquids obey
fractional (including nontrivial mutual) exclusion statistics. Their statistics
matrix can be determined from several possible state-counting scheme, involving
different assumptions on statistical correlations. Thermal activation of
quasiparticle pairs and thermodynamic properties of the fractional quantum Hall
liquids near fillings ( odd) at low temperature are studied in the
approximation of generalized ideal gas. The existence of hierarchical states in
the fractional quantum Hall effect is shown to be a manifestation of the
exclusonic nature of the relevant quasiparticles. For magnetic properties, a
paramagnetism-diamagnetism transition appears to be possible at finite
temperature.Comment: latex209, REVTE
Action Principle for the Classical Dual Electrodynamics
The purpose of this paper is to formulate an action principle which allows
for the construction of a classical lagrangean including both electric and
magnetic currents. The lagrangean is non-local and shown to yield all the
expected (local) equations for dual electrodynamics.Comment: latex, 8 pages, no figure
Half-metallicity and efficient spin injection in AlN/GaN:Cr (0001) heterostructure
First-principles investigations of the structural, electronic and magnetic
properties of Cr-doped AlN/GaN (0001) heterostructures reveal that Cr
segregates into the GaN region, that these interfaces retain their important
half-metallic character and thus yield efficient (100 %) spin polarized
injection from a ferromagnetic GaN:Cr electrode through an AlN tunnel barrier -
whose height and width can be controlled by adjusting the Al concentration in
the graded bandgap engineered Al(1-x)Ga(x)N (0001) layers.Comment: submitted for publicatio
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