6,333 research outputs found
Generalized W-Class State and its Monogamy Relation
We generalize the W class of states from qubits to qudits and prove
that their entanglement is fully characterized by their partial entanglements
even for the case of the mixture that consists of a W-class state and a product
state .Comment: 12 pages, 1 figur
Spheres and Prolate and Oblate Ellipsoids from an Analytical Solution of Spontaneous Curvature Fluid Membrane Model
An analytic solution for Helfrich spontaneous curvature membrane model (H.
Naito, M.Okuda and Ou-Yang Zhong-Can, Phys. Rev. E {\bf 48}, 2304 (1993); {\bf
54}, 2816 (1996)), which has a conspicuous feature of representing the circular
biconcave shape, is studied. Results show that the solution in fact describes a
family of shapes, which can be classified as: i) the flat plane (trivial case),
ii) the sphere, iii) the prolate ellipsoid, iv) the capped cylinder, v) the
oblate ellipsoid, vi) the circular biconcave shape, vii) the self-intersecting
inverted circular biconcave shape, and viii) the self-intersecting nodoidlike
cylinder. Among the closed shapes (ii)-(vii), a circular biconcave shape is the
one with the minimum of local curvature energy.Comment: 11 pages, 11 figures. Phys. Rev. E (to appear in Sept. 1999
Conditional teleportation using optical squeezers and photon counting
We suggest a scheme of using two-mode squeezed vacuum for conditional
teleportation of quantum states of optical field. Alice mixes the input state
with one of the squeezed modes on another squeezing device and detects the
output photon numbers. The result is then communicated to Bob who shifts the
photon number of his part accordingly. This is a principally realizable
modification of the recent scheme [G.J. Milburn and S.L. Braunstein, Phys. Rev.
A 60, 937 (1999)] where measurements of photon number difference and phase sum
are considered. We show that for some classes of states this method can yield
very high fidelity of teleportation, nevertheless, the success probability may
be limited.Comment: 5 pages, 4 figures; notations simplified, more explicit explanatio
A Dispersive Analysis on the and Resonances in Processes
We estimate the di-photon coupling of , and
resonances in a coupled channel dispersive approach. The di-photon
coupling is also reinvestigated using a single channel matrix for
scattering with better analyticity property, and it is found to be
significantly smaller than that of a state. Especially we also
estimate the di-photon coupling of the third sheet pole located near
threshold, denoted as .
It is argued that this third sheet pole may be originated from a coupled
channel Breit-Wigner description of the resonance.Comment: 24 pages and 13 eps figures. A nuerical bug in previous version is
fixed. Some results changed. References and new figures added. Version to
appear in Phys. Rev.
Do topology and ferromagnetism cooperate at the EuS/BiSe interface?
We probe the local magnetic properties of interfaces between the insulating
ferromagnet EuS and the topological insulator BiSe using low energy
muon spin rotation (LE-SR). We compare these to the interface between EuS
and the topologically trivial metal, titanium. Below the magnetic transition of
EuS, we detect strong local magnetic fields which extend several nm into the
adjacent layer and cause a complete depolarization of the muons. However, in
both BiSe and titanium we measure similar local magnetic fields,
implying that their origin is mostly independent of the topological properties
of the interface electronic states. In addition, we use resonant soft X-ray
angle resolved photoemission spectroscopy (SX-ARPES) to probe the electronic
band structure at the interface between EuS and BiSe. By tuning the
photon energy to the Eu anti-resonance at the Eu pre-edge we are able to
detect the BiSe conduction band, through a protective AlO
capping layer and the EuS layer. Moreover, we observe a signature of an
interface-induced modification of the buried BiSe wave functions and/or
the presence of interface states
Approaching the Heisenberg limit with two mode squeezed states
Two mode squeezed states can be used to achieve Heisenberg limit scaling in
interferometry: a phase shift of can be
resolved. The proposed scheme relies on balanced homodyne detection and can be
implemented with current technology. The most important experimental
imperfections are studied and their impact quantified.Comment: 4 pages, 7 figure
Attenuation of light in different rock types and implications for rock surface luminescence dating
Narrowband frequency tunable light source of continuous quadrature entanglement
We report the observation of non-classical quantum correlations of continuous
light variables from a novel type of source. It is a frequency non-degenerate
optical parametric oscillator below threshold, where signal and idler fields
are separated by 740MHz corresponding to two free spectrum ranges of the
parametric oscillator cavity. The degree of entanglement observed, - 3.8 dB, is
the highest to-date for a narrowband tunable source suitable for atomic quantum
memory and other applications in atomic physics. Finally we use the latter to
visualize the Einstein-Podolsky-Rosen paradox.Comment: 11 pages, 9 figures, LaTe
Signaling, Entanglement, and Quantum Evolution Beyond Cauchy Horizons
Consider a bipartite entangled system half of which falls through the event
horizon of an evaporating black hole, while the other half remains coherently
accessible to experiments in the exterior region. Beyond complete evaporation,
the evolution of the quantum state past the Cauchy horizon cannot remain
unitary, raising the questions: How can this evolution be described as a
quantum map, and how is causality preserved? What are the possible effects of
such nonstandard quantum evolution maps on the behavior of the entangled
laboratory partner? More generally, the laws of quantum evolution under extreme
conditions in remote regions (not just in evaporating black-hole interiors, but
possibly near other naked singularities and regions of extreme spacetime
structure) remain untested by observation, and might conceivably be non-unitary
or even nonlinear, raising the same questions about the evolution of entangled
states. The answers to these questions are subtle, and are linked in unexpected
ways to the fundamental laws of quantum mechanics. We show that terrestrial
experiments can be designed to probe and constrain exactly how the laws of
quantum evolution might be altered, either by black-hole evaporation, or by
other extreme processes in remote regions possibly governed by unknown physics.Comment: Combined, revised, and expanded version of quant-ph/0312160 and
hep-th/0402060; 13 pages, RevTeX, 2 eps figure
Demonstration of Non-Deterministic Quantum Logic Operations using Linear Optical Elements
Knill, Laflamme, and Milburn recently showed that non-deterministic quantum
logic operations could be performed using linear optical elements, additional
photons (ancilla), and post-selection based on the output of single-photon
detectors [Nature 409, 46 (2001)]. Here we report the experimental
demonstration of two logic devices of this kind, a destructive controlled-NOT
(CNOT) gate and a quantum parity check. These two devices can be combined with
a pair of entangled photons to implement a conventional (non-destructive) CNOT
that succeeds with a probability of 1/4.Comment: 4 pages, 5 figures; Minor change
- …