198 research outputs found
The strong Bell inequalities: A proposed experimental test
All previous experimental tests of Bell inequalities have required additional assumptions. The strong Bell inequalities (i.e. those requiring no additional assumptions) have never been tested. An experiment has been designed that can, for the first time, provide a definitive test of the strong Bell inequalities. Not only will the detector efficiency loophole be closed; but the locality condition will also be rigorously enforced. The experiment involves producing two Hg-199 atoms by a resonant Raman dissociation of a mercury dimer ((199)Hg2) that is in an electronic and nuclear spin singlet state. Bell inequalities can be tested by measuring angular momentum correlations between the spin one-half nuclei of the two Hg-199 atoms. The method used to make these latter measurements will be described
Proposal for a Loophole-Free Test of the Bell Inequalities
Journals published by the American Physical Society can be found at http://publish.aps.org/A proposal for an experimental realization of Bohm's spin-1/2 particle version of the Einstein-Podolsky-Rosen experiment is described. Two Hg-199 atoms, each with nuclear spin 1/2, are produced in an entangled state with total nuclear spin zero. Such a state is obtained by dissociation of dimers of the Hg-199(2) isotopomer using a spectroscopically selective stimulated Raman process. The measurement of nuclear spin correlations between the two atoms in this entangled state is achieved by detection of the atoms using a spin state selective two-photon excitation-ionization scheme. The experiment will not only close the detector efficiency loophole, but in addition will permit enforcement of the locality condition
Observation of interference fringes in Autler-Townes line shapes
Journals published by the American Physical Society can be found at http://publish.aps.org/We observe Ramsey fringes in the absorption line shape for a weak optical field probing the transition between an unperturbed quantum state and one that is dynamically Stark shifted by a strong pump field
Ultra-Slow Light and Enhanced Nonlinear Optical Effects in a Coherently Driven Hot Atomic Gas
We report the observation of small group velocities of order 90 meters per
second, and large group delays of greater than 0.26 ms, in an optically dense
hot rubidium gas (~360 K). Media of this kind yield strong nonlinear
interactions between very weak optical fields, and very sharp spectral
features. The result is in agreement with previous studies on nonlinear
spectroscopy of dense coherent media
Enhancing Acceleration Radiation from Ground-State Atoms via Cavity Quantum Electrodynamics
When ground state atoms are accelerated through a high Q microwave cavity,
radiation is produced with an intensity which can exceed the intensity of Unruh
acceleration radiation in free space by many orders of magnitude. The cavity
field at steady state is described by a thermal density matrix under most
conditions. However, under some conditions gain is possible, and when the atoms
are injected in a regular fashion, the radiation can be produced in a squeezed
state
Analysis of Neptune's 2017 Bright Equatorial Storm
We report the discovery of a large (8500 km diameter) infrared-bright
storm at Neptune's equator in June 2017. We tracked the storm over a period of
7 months with high-cadence infrared snapshot imaging, carried out on 14 nights
at the 10 meter Keck II telescope and 17 nights at the Shane 120 inch reflector
at Lick Observatory. The cloud feature was larger and more persistent than any
equatorial clouds seen before on Neptune, remaining intermittently active from
at least 10 June to 31 December 2017. Our Keck and Lick observations were
augmented by very high-cadence images from the amateur community, which
permitted the determination of accurate drift rates for the cloud feature. Its
zonal drift speed was variable from 10 June to at least 25 July, but remained a
constant m s from 30 September until at least 15
November. The pressure of the cloud top was determined from radiative transfer
calculations to be 0.3-0.6 bar; this value remained constant over the course of
the observations. Multiple cloud break-up events, in which a bright cloud band
wrapped around Neptune's equator, were observed over the course of our
observations. No "dark spot" vortices were seen near the equator in HST imaging
on 6 and 7 October. The size and pressure of the storm are consistent with
moist convection or a planetary-scale wave as the energy source of convective
upwelling, but more modeling is required to determine the driver of this
equatorial disturbance as well as the triggers for and dynamics of the observed
cloud break-up events.Comment: 42 pages, 14 figures, 6 tables; Accepted to Icaru
Ultrasensitive detection of waste products in water using fluorescence emission cavity-enhanced spectroscopy
Clean water is paramount to human health. In this article, we present a technique for detection of trace amounts of human or animal waste products in water using fluorescence emission cavity-enhanced spectroscopy. The detection of femtomolar concentrations of urobilin, a metabolic byproduct of heme metabolism that is excreted in both human and animal waste in water, was achieved through the use of an integrating cavity. This technique could allow for real-time assessment of water quality without the need for expensive laboratory equipment
GUT Baryogenesis after Preheating
At the end of inflation the universe is frozen in a near zero-entropy state
with energy density in a coherent scalar field and must be ``defrosted'' to
produce the observed entropy and baryon number. We propose that the baryon
asymmetry is generated by the decay of supermassive Grand Unified Theory (GUT)
bosons produced non-thermally in a preheating phase after inflation. We show
that baryogenesis is possible for an inflaton masses of order 10^{13} GeV and a
GUT Higgs boson mass of order 10^{14} GeV, thus solving many drawbacks facing
GUT baryogenesis in the old reheating scenario.Comment: 4 pages, version to be published in Phys. Rev. Let
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