115,376 research outputs found
Comment on "Spectroscopic Evidence for Multiple Order Parameter Components in the Heavy Fermion Superconductor CeCoIn"
Recently, Rourke et al. reported point-contact spectroscopy results on the
heavy-fermion superconductor CeCoIn [1]. They obtained conductance spectra
on the c-axis surfaces of CeCoIn single crystals. Their major claims are
two-fold: CeCoIn has i) d-wave pairing symmetry and ii) two coexisting
order parameter components. In this Comment, we show that these claims are not
warranted by the data presented. [1] Rourke et al., Phys. Rev. Lett. 94, 107005
(2005).Comment: accepted for publication in Phys. Rev. Lett., final for
Generalizing the DGLAP Evolution of Fragmentation Functions to the Smallest x Values
An approach which unifies the Double Logarithmic Approximation at small x and
the leading order DGLAP evolution of fragmentation functions at large x is
presented. This approach reproduces exactly the Modified Leading Logarithm
Approximation, but is more complete due to the degrees of freedom given to the
quark sector and the inclusion of the fixed order terms. We find that data from
the largest x values to the peak region can be better fitted than with other
approaches.Comment: 10 pages, 3 figure
Free boson representation of at level one
We construct a realization of the central extension of super-Yangian double
at level-one in terms of free boson fields with
a continuous parameter.Comment: 9 pages, latex, reference revise
First-principles calculations of a high-pressure synthesized compound PtC
First-principles density-functional method is used to study the recently
high-pressure synthesized compound PtC. It is confirmed by our calculations
that the platinum carbide has a zinc-blende ground-state phase at zero pressure
and the rock-salt structure is a high-pressure phase. The theoretical
transition pressure from zinc-blende to rock-salt is determined to be 52GPa.
Furthermore, our calculation shows the possibility that the experimentally
synthesized PtC by Ono et al. under high pressure condition might undergo a
transition from rock-salt structure to zinc-blende after the pressure quench to
ambient condition.Comment: A revised versio
Optimal transfer of an unknown state via a bipartite operation
A fundamental task in quantum information science is to transfer an unknown
state from particle to particle (often in remote space locations) by
using a bipartite quantum operation . We suggest the power of
for quantum state transfer (QST) to be the maximal average
probability of QST over the initial states of particle and the
identifications of the state vectors between and . We find the QST power
of a bipartite quantum operations satisfies four desired properties between two
-dimensional Hilbert spaces. When and are qubits, the analytical
expressions of the QST power is given. In particular, we obtain the exact
results of the QST power for a general two-qubit unitary transformation.Comment: 6 pages, 1 figur
Secondary "Smile"-gap in the density of states of a diffusive Josephson junction for a wide range of contact types
The superconducting proximity effect leads to strong modifications of the
local density of states in diffusive or chaotic cavity Josephson junctions,
which displays a phase-dependent energy gap around the Fermi energy. The
so-called minigap of the order of the Thouless energy is
related to the inverse dwell time in the diffusive region in the limit
, where is the superconducting energy gap.
In the opposite limit of a large Thouless energy , a
small new feature has recently attracted attention, namely, the appearance of a
further secondary gap, which is around two orders of magnitude smaller compared
to the usual superconducting gap. It appears in a chaotic cavity just below the
superconducting gap edge and vanishes for some value of the phase
difference between the superconductors. We extend previous theory restricted to
a normal cavity connected to two superconductors through ballistic contacts to
a wider range of contact types. We show that the existence of the secondary gap
is not limited to ballistic contacts, but is a more general property of such
systems. Furthermore, we derive a criterion which directly relates the
existence of a secondary gap to the presence of small transmission eigenvalues
of the contacts. For generic continuous distributions of transmission
eigenvalues of the contacts, no secondary gap exists, although we observe a
singular behavior of the density of states at . Finally, we provide a
simple one-dimensional scattering model which is able to explain the
characteristic "smile" shape of the secondary gap.Comment: 12 pages, 12 figure
"Smile"-gap in the density of states of a cavity between superconductors
The density of Andreev levels in a normal metal () in contact with two
superconductors () is known to exhibit an induced minigap related to the
inverse dwell time. We predict a small secondary gap just below the
superconducting gap edge---a feature that has been overlooked so far in
numerous studies of the density of states in structures. In a generic
structure with being a chaotic cavity, the secondary gap is the widest at
zero phase bias. It closes at some finite phase bias, forming the shape of a
"smile". Asymmetric couplings give even richer gap structures near the phase
difference \pi. All the features found should be amendable to experimental
detection in high-resolution low-temperature tunneling spectroscopy.Comment: 5 pages, 4 figure
Magneto-controlled nonlinear optical materials
We exploit theoretically a magneto-controlled nonlinear optical material
which contains ferromagnetic nanoparticles with a non-magnetic metallic
nonlinear shell in a host fluid. Such an optical material can have anisotropic
linear and nonlinear optical properties and a giant enhancement of
nonlinearity, as well as an attractive figure of merit.Comment: 11 pages, 2 figures. To be published in Appl. Phys. Let
- …