67,346 research outputs found
On the Triality Theory for a Quartic Polynomial Optimization Problem
This paper presents a detailed proof of the triality theorem for a class of
fourth-order polynomial optimization problems. The method is based on linear
algebra but it solves an open problem on the double-min duality left in 2003.
Results show that the triality theory holds strongly in a tri-duality form if
the primal problem and its canonical dual have the same dimension; otherwise,
both the canonical min-max duality and the double-max duality still hold
strongly, but the double-min duality holds weakly in a symmetrical form. Four
numerical examples are presented to illustrate that this theory can be used to
identify not only the global minimum, but also the largest local minimum and
local maximum.Comment: 16 pages, 1 figure; J. Industrial and Management Optimization, 2011.
arXiv admin note: substantial text overlap with arXiv:1104.297
Optimal Controlled Teleportation
We give the analytic expressions of maximal probabilities of successfully
controlled teleportating an unknown qubit via every kind of tripartite states.
Besides, another kind of localizable entanglement is also determined.
Furthermore, we give the sufficient and necessary condition that a three-qubit
state can be collapsed to an EPR pair by a measurement on one qubit, and
characterize the three-qubit states that can be used as quantum channel for
controlled teleporting a qubit of unknown information with unit probability and
with unit fidelity.Comment: 4 page
A Simultaneous Quantum Secure Direct Communication Scheme between the Central Party and Other M Parties
We propose a simultaneous quantum secure direct communication scheme between
one party and other three parties via four-particle GHZ states and swapping
quantum entanglement. In the scheme, three spatially separated senders, Alice,
Bob and Charlie, transmit their secret messages to a remote receiver Diana by
performing a series local operations on their respective particles according to
the quadripartite stipulation. From Alice, Bob, Charlie and Diana's Bell
measurement results, Diana can infer the secret messages. If a perfect quantum
channel is used, the secret messages are faithfully transmitted from Alice, Bob
and Charlie to Diana via initially shared pairs of four-particle GHZ states
without revealing any information to a potential eavesdropper. As there is no
transmission of the qubits carrying the secret message in the public channel,
it is completely secure for the direct secret communication. This scheme can be
considered as a network of communication parties where each party wants to
communicate secretly with a central party or server.Comment: 4 pages, no figur
Probabilistic teleportation of unknown two-particle state via POVM
We propose a scheme for probabilistic teleportation of unknown two-particle
state with partly entangled four-particle state via POVM. In this scheme the
teleportation of unknown two-particle state can be realized with certain
probability by performing two Bell state measurements, a proper POVM and a
unitary transformation.Comment: 5 pages, no figur
Analysis of interdiffusion between SmFeAsO0.92F0.08 and metals for ex situ fabrication of superconducting wire
We demonstrate the fabrication of superconducting SmFeAsO1-xFx (Sm-1111)
wires by using the ex-situ powder-in-tube technique. Sm-1111 powder and a
binder composed of SmF3, samarium arsenide, and iron arsenide were used to
synthesize the superconducting core. Although the F content of Sm-1111 is
reduced in the process of ex-situ fabrication, the binder compensates by
sufficiently supplementing the F content, thereby preventing a decrease in the
superconducting transition temperature and a shrinking of the superconducting
volume fraction. Thus, in the superconducting Sm-1111 wire with the binder, the
transport critical current density reaches the highest value of ~4000 A/cm2 at
4.2 K
Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
We report single-dish multi-transition measurements of the 12^CO, HCN, and
HCO^+ molecular line emission as well as HNC J=1-0 and HNCO in the two
ultraluminous infra-red galaxies Arp220 and NGC6240. Using this new molecular
line inventory, in conjunction with existing data in the literature, we
compiled the most extensive molecular line data sets to date for such galaxies.
The many rotational transitions, with their different excitation requirements,
allow the study of the molecular gas over a wide range of different densities
and temperatures with significant redundancy, and thus allow good constraints
on the properties of the dense gas in these two systems. The mass (~(1-2) x
10^10 Msun) of dense gas (>10^5-6 cm^-3) found accounts for the bulk of their
molecular gas mass, and is consistent with most of their IR luminosities
powered by intense star bursts while self-regulated by O,B star cluster
radiative pressure onto the star-forming dense molecular gas. The highly
excited HCN transitions trace a gas phase ~(10-100)x denser than that of the
sub-thermally excited HCO^+ lines (for both galaxies). These two phases are
consistent with an underlying density-size power law found for Galactic GMCs
(but with a steeper exponent), with HCN lines tracing denser and more compact
regions than HCO^+. Whether this is true in IR-luminous, star forming galaxies
in general remains to be seen, and underlines the need for observations of
molecular transitions with high critical densities for a sample of bright
(U)LIRGs in the local Universe -- a task for which the HI-FI instrument on
board Herschel is ideally suited to do.Comment: 38 pages (preprint ApJ style), 3 figures, accepted for Ap
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