38,447 research outputs found
Simple Scheme for Efficient Linear Optics Quantum Gates
We describe the construction of a conditional quantum control-not (CNOT) gate
from linear optical elements following the program of Knill, Laflamme and
Milburn [Nature {\bf 409}, 46 (2001)]. We show that the basic operation of this
gate can be tested using current technology. We then simplify the scheme
significantly.Comment: Problems with PDF figures correcte
A New Young Diagrammatic Method For Kronecker Products of O(n) and Sp(2m)
A new simple Young diagrammatic method for Kronecker products of O(n) and
Sp(2m) is proposed based on representation theory of Brauer algebras. A general
procedure for the decomposition of tensor products of representations for O(n)
and Sp(2m) is outlined, which is similar to that for U(n) known as the
Littlewood rules together with trace contractions from a Brauer algebra and
some modification rules given by King.Comment: Latex, 11 pages, no figure
On the slowly time dependent problem of squeeze film bearings
Time dependency of spherical squeeze-film bearing for use in suspension of precision gyroscope outpu
Dynamic response of a double squeeze-film thrust plate
Dynamic response of gaseous double squeeze film thrust plate for bearing
A burst from the direction of UZ Fornacis with XMM-Newton
The XMM-Newton pointing towards the magnetic cataclysmic variable UZ For
finds the source to be a factor > 10^3 fainter than previous EXOSAT and ROSAT
observations. The source was not detected for the majority of a 22 ksec
exposure with the EPIC cameras, suggesting that the accretion rate either
decreased, or stopped altogether. However a 1.1 ksec burst was detected from UZ
For during the observation. Spectral fits favour optically thin, kT = 4.4 keV
thermal emission. Detection of the burst by the on-board Optical Monitor
indicates that this was most probably an accretion event. The 0.1-10 keV
luminosity of 2.1 x 10^30 erg/s is typical for accretion shock emission from
high state polars and would result from the potential energy release of ~ 10^16
g of gas. There is no significant soft excess due to reprocessing in the white
dwarf atmosphere.Comment: 7 pages, 2 postscript figures, ApJL, in pres
Dense-coding quantum key distribution based on continuous-variable entanglement
We proposed a scheme of continuous-variable quantum key distribution, in
which the bright Einstein-Podolsky-Rosen entangled optical beams are utilized.
The source of the entangled beams is placed inside the receiving station, where
half of the entangled beams are transmitted with round trip and the other half
are retained by the receiver. The amplitude and phase signals modulated on the
signal beam by the sender are simultaneously extracted by the authorized
receiver with the scheme of the dense-coding correlation measurement for
continuous quantum variables, thus the channel capacity is significantly
improved. Two kinds of possible eavesdropping are discussed. The mutual
information and the secret key rates are calculated and compared with those of
unidirectional transmission schemes
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