8,779 research outputs found
Dissipative preparation of entanglement in optical cavities
We propose a novel scheme for the preparation of a maximally entangled state
of two atoms in an optical cavity. Starting from an arbitrary initial state, a
singlet state is prepared as the unique fixed point of a dissipative quantum
dynamical process. In our scheme, cavity decay is no longer undesirable, but
plays an integral part in the dynamics. As a result, we get a qualitative
improvement in the scaling of the fidelity with the cavity parameters. Our
analysis indicates that dissipative state preparation is more than just a new
conceptual approach, but can allow for significant improvement as compared to
preparation protocols based on coherent unitary dynamics.Comment: 4 pages, 2 figure
On the Observation of Phase Transitions in Collisions of Elementary Matter
We investigate the excitation function of directed flow, which can provide a
clear signature of the creation of the QGP and demonstrate that the minimum of
the directed flow does not correspond to the softest point of the EoS for
isentropic expansion. A novel technique measuring the compactness is introduced
to determine the QGP transition in relativistic-heavy ion collisions: The QGP
transition will lead to higher compression and therefore to higher compactness
of the source in coordinate space. This effect can be observed by pion
interferometry. We propose to measure the compactness of the source in the
appropriate principal axis frame of the compactness tensor in coordinate space.Comment: LaTeX, 8 pages, 6 figures, Conference proceedings to CRIS 2000, 3rd
Catania Relativistic Ion Studie
Entropy Production in Collisions of Relativistic Heavy Ions -- a signal for Quark-Gluon Plasma phase transition?
Entropy production in the compression stage of heavy ion collisions is
discussed within three distinct macroscopic models (i.e. generalized RHTA,
geometrical overlap model and three-fluid hydrodynamics). We find that within
these models \sim 80% or more of the experimentally observed final-state
entropy is created in the early stage. It is thus likely followed by a nearly
isentropic expansion. We employ an equation of state with a first-order phase
transition. For low net baryon density, the entropy density exhibits a jump at
the phase boundary. However, the excitation function of the specific entropy
per net baryon, S/A, does not reflect this jump. This is due to the fact that
for final states (of the compression) in the mixed phase, the baryon density
\rho_B increases with \sqrt{s}, but not the temperature T. Calculations within
the three-fluid model show that a large fraction of the entropy is produced by
nuclear shockwaves in the projectile and target. With increasing beam energy,
this fraction of S/A decreases. At \sqrt{s}=20 AGeV it is on the order of the
entropy of the newly produced particles around midrapidity. Hadron ratios are
calculated for the entropy values produced initially at beam energies from 2 to
200 AGeV.Comment: 17 pages, 8 figures, uses epsfig.sty; Submitted to Nucl.Phys.
Reasonable Accommodation Under the ADA
This brochure is one of a series on human resources practices and workplace accommodations for persons with disabilities edited by Susanne M. Bruyère, Ph.D., CRC, SPHR, Director, Program on Employment and Disability, School of Industrial and Labor Relations – Extension Division, Cornell University. Cornell University was funded in the early 1990’s by the U.S. Department of Education National Institute on Disability and Rehabilitation Research as a National Materials Development Project on the employment provisions (Title I) of the ADA (Grant #H133D10155). These updates, and the development of new brochures, have been funded by Cornell’s Program on Employment and Disability, the Pacific Disability and Business Technical Assistance Center, and other supporters
Deuteron Momentum Distribution in KD2HPO4
The momentum distribution in KD2PO4(DKDP) has been measured using neutron
Compton scattering above and below the weakly first order
paraelectric-ferroelectric phase transition(T=229K). There is very litte
difference between the two distributions, and no sign of the coherence over two
locations for the proton observed in the paraelectric phase, as in KH2PO4(KDP).
We conclude that the tunnel splitting must be much less than 20mev. The width
of the distribution indicates that the effective potential for DKDP is
significantly softer than that for KDP. As electronic structure calculations
indicate that the stiffness of the potential increases with the size of the
coherent region locally undergoing soft mode fluctuations, we conclude that
there is a mass dependent quantum coherence length in both systems.Comment: 6 pages 5 figure
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