371 research outputs found
Optimal States for Bell inequality Violations using Quadrature Phase Homodyne Measurements
We identify what ideal correlated photon number states are to required to
maximize the discrepancy between local realism and quantum mechanics when a
quadrature homodyne phase measurement is used. Various Bell inequality tests
are considered.Comment: 6 pages, 5 Figure
s-ordered phase-sum and phase-difference distribuitons of entangled coherent states
The -ordered phase-sum and phase-difference distributions are considered
for Bell-like superpositions of two-mode coherent states. The distributions are
sensitive, respectively, to the sum and difference of the phases of the
entangled coherent states. They show loss of information about the entangled
state and may take on negative values for some orderings .Comment: 8 pages, 2 figures, iopart. accepted for publication in J. Opt. B:
Quantum Semiclass Op
Engineering cavity-field states by projection synthesis
We propose a reliable scheme for engineering a general cavity-field state.
This is different from recently presented strategies,where the cavity is
supposed to be initially empty and the field is built up photon by photon
through resonant atom-field interactions. Here, a coherent state is previously
injected into the cavity. So, the Wigner distribution function of the desired
state is constructed from that of the initially coherent state. Such an
engineering process is achieved through an adaptation of the recently proposed
technique of projection synthesis to cavity QED phenomena.Comment: 5 ps pages plus 3 included figure
The Heavy Photon Search beamline and its performance
The Heavy Photon Search (HPS) is an experiment to search for a hidden sector
photon, aka a heavy photon or dark photon, in fixed target electroproduction at
the Thomas Jefferson National Accelerator Facility (JLab). The HPS experiment
searches for the ee decay of the heavy photon with bump hunt and
detached vertex strategies using a compact, large acceptance forward
spectrometer, consisting of a silicon microstrip detector (SVT) for tracking
and vertexing, and a PbWO electromagnetic calorimeter for energy
measurement and fast triggering. To achieve large acceptance and good vertexing
resolution, the first layer of silicon detectors is placed just 10 cm
downstream of the target with the sensor edges only 500 m above and below
the beam. Placing the SVT in such close proximity to the beam puts stringent
requirements on the beam profile and beam position stability. As part of an
approved engineering run, HPS took data in 2015 and 2016 at 1.05 GeV and 2.3
GeV beam energies, respectively. This paper describes the beam line and its
performance during that data taking
Search for flavor-changing neutral currents and lepton-family-number violation in two-body D0 decays
Results of a search for the three neutral charm decays, D0 -> mu e, D0 -> mu
mu, and D0 -> e e, are presented. This study was based on data collected in
Experiment 789 at the Fermi National Accelerator Laboratory using 800 GeV/c
proton-Au and proton-Be interactions. No evidence is found for any of the
decays. Upper limits on the branching ratios, at the 90% confidence level, are
obtained.Comment: 28 pages, 18 figures. Submitted to Physical Review
Gaussian Wigner distributions and hierarchies of nonclassical states in quantum optics-The single mode case
A recently introduced hierarchy of states of a single mode quantised
radiation field is examined for the case of centered Guassian Wigner
distributions. It is found that the onset of squeezing among such states
signals the transition to the strongly nonclassical regime. Interesting
consequences for the photon number distribution, and explicit representations
for them, are presented.Comment: 11 Pages Revtex one eps figure. Replaced with minor changes in ref
Quantum Nondemolition State Measurement via Atomic Scattering in Bragg Regime
We suggest a quantum nondemolition scheme to measure a quantized cavity field
state using scattering of atoms in general Bragg regime. Our work extends the
QND measurement of a cavity field from Fock state, based on first order Bragg
deflection [9], to any quantum state based on Bragg deflection of arbitrary
order. In addition a set of experimental parameters is provided to perform the
experiment within the frame work of the presently available technology.Comment: 11 pages text, 4 eps figures, to appear in letter section of journal
of physical society of Japa
Third Generation Familons, B Factories, and Neutrino Cosmology
We study the physics of spontaneously broken family symmetries acting on the
third generation. Massless familons (or Majorons) associated with such
broken symmetries are motivated especially by cosmological scenarios with
decaying tau neutrinos. We first note that, in marked contrast with the case
for the first two generations, constraints on third generation familon
couplings are poor, and are, in fact, non-existent at present in the hadronic
sector. We derive new bounds from -- mixing, , , and astrophysics. The resulting constraints on
familon decay constants are still much weaker than those for the first and
second generation. We then discuss the promising prospects for significant
improvements from searches for , , and with the current CLEO, ARGUS, and LEP data. Finally, we note that
future constraints from CLEO III and the factories will probe decay
constants beyond 10^8 GeV, well within regions of parameter space favored by
proposed scenarios in neutrino cosmology.Comment: ReVTeX, 33 pages, 6 figures, notation improved, references added,
revised to conform to pubished versio
The Haroche-Ramsey experiment as a generalized measurement
A number of atomic beam experiments, related to the Ramsey experiment and a
recent experiment by Brune et al., are studied with respect to the question of
complementarity. Three different procedures for obtaining information on the
state of the incoming atom are compared. Positive operator-valued measures are
explicitly calculated. It is demonstrated that, in principle, it is possible to
choose the experimental arrangement so as to admit an interpretation as a joint
non-ideal measurement yielding interference and ``which-way'' information.
Comparison of the different measurements gives insight into the question of
which information is provided by a (generalized) quantum mechanical
measurement. For this purpose the subspaces of Hilbert-Schmidt space, spanned
by the operators of the POVM, are determined for different measurement
arrangements and different values of the parameters.Comment: REVTeX, 22 pages, 5 figure
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