Conditional probabilities for a single photon at a beam splitter

Published versio

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 $s$-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 $s$.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 e$^+$e$^-$ 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$_4$ 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 $\mu$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) $f$ 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 $B^0$--$\bar{B}^0$ mixing, $B^0 \to l^+ l'^-$, $b\to s\nu\bar{\nu}$, 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 $\tau\to l f$, $B\to (\pi, K) f$, and $b\to (d,s) f$ with the current CLEO, ARGUS, and LEP data. Finally, we note that future constraints from CLEO III and the $B$ 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