2,463 research outputs found
Generating and probing a two-photon Fock state with a single atom in a cavity
A two-photon Fock state is prepared in a cavity sustaining a "source mode "
and a "target mode", with a single circular Rydberg atom. In a third-order
Raman process, the atom emits a photon in the target while scattering one
photon from the source into the target. The final two-photon state is probed by
measuring by Ramsey interferometry the cavity light shifts induced by the
target field on the same atom. Extensions to other multi-photon processes and
to a new type of micromaser are briefly discussed
Exploring Oxidation in the Remote Free Troposphere: Insights from Atmospheric Tomography (ATom)
Earth's atmosphere oxidizes the greenhouse gas methane and other gases, thus determining their lifetimes and oxidation products. Much of this oxidation occurs in the remote, relatively clean free troposphere above the planetary boundary layer, where the oxidation chemistry is thought to be much simpler and better understood than it is in urban regions or forests. The NASA airborne Atmospheric Tomography study (ATom) was designed to produce cross sections of the detailed atmospheric composition in the remote atmosphere over the Pacific and Atlantic Oceans during four seasons. As part of the extensive ATom data set, measurements of the atmosphere's primary oxidant, hydroxyl (OH), and hydroperoxyl (HO₂) are compared to a photochemical box model to test the oxidation chemistry. Generally, observed and modeled median OH and HO₂ agree to with combined uncertainties at the 2σ confidence level, which is ~±40%. For some seasons, this agreement is within ~±20% below 6 km altitude. While this test finds no significant differences, OH observations increasingly exceeded modeled values at altitudes above 8 km, becoming ~35% greater, which is near the combined uncertainties. Measurement uncertainty and possible unknown measurement errors complicate tests for unknown chemistry or incorrect reaction rate coefficients that would substantially affect the OH and HO₂ abundances. Future analysis of detailed comparisons may yield additional discrepancies that are masked in the median values
Kinetic theory of cluster impingement in the framework of statistical mechanics of rigid disks
The paper centres on the evaluation of the function n(theta)=N(theta)/N0,
that is the normalized number of islands as a function of coverage 0<theta<1,
given N0 initial nucleation centres (dots) having any degree of spatial
correlation. A mean field approach has been employed: the islands have the same
size at any coverage. In particular, as far as the random distribution of dots
is concerned, the problem has been solved by considering the contribution of
binary collisions between islands only. With regard to correlated dots, we
generalize a method previously applied to the random case only. In passing, we
have made use of the exclusion probability reported in [S. Torquato, B. Lu, J.
Rubinstein, Phys.Rev.A 41, 2059 (1990)], for determining the kinetics of
surface coverage in the case of correlated dots, improving our previous
calculation [M. Tomellini, M. Fanfoni, M. Volpe Phys. Rev.B 62, 11300, (2000)].Comment: 10 pages, 3 figure
Test of quantum nonlocality for cavity fields
There have been studies on formation of quantum-nonlocal states in spatially
separate two cavities. We suggest a nonlocal test for the field prepared in the
two cavities. We couple classical driving fields with the cavities where a
nonlocal state is prepared. Two independent two-level atoms are then sent
through respective cavities to interact off-resonantly with the cavity fields.
The atomic states are measured after the interaction. Bell's inequality can be
tested by the joint probabilities of two-level atoms being in their excited or
ground states. We find that quantum nonlocality can also be tested using a
single atom sequentially interacting with the two cavities. Potential
experimental errors are also considered. We show that with the present
experimental condition of 5% error in the atomic velocity distribution, the
violation of Bell's inequality can be measured.Comment: 14pages, 2figures. accepted to Phys. Rev.
Phase space tweezers for tailoring cavity fields by quantum Zeno dynamics
We discuss an implementation of Quantum Zeno Dynamics in a Cavity Quantum
Electrodynamics experiment. By performing repeated unitary operations on atoms
coupled to the field, we restrict the field evolution in chosen subspaces of
the total Hilbert space. This procedure leads to promising methods for
tailoring non-classical states. We propose to realize `tweezers' picking a
coherent field at a point in phase space and moving it towards an arbitrary
final position without affecting other non-overlapping coherent components.
These effects could be observed with a state-of-the-art apparatus
Quantum bit detector
We propose and analyze an experimental scheme of quantum nondemolition
detection of monophotonic and vacuum states in a superconductive toroidal
cavity by means of Rydberg atoms.Comment: 4 pages, 3 figure
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
Entanglement of a Mesoscopic Field with an Atom induced by Photon Graininess in a Cavity
We observe that a mesoscopic field made of several tens of microwave photons
exhibits quantum features when interacting with a single Rydberg atom in a
high-Q cavity. The field is split into two components whose phases differ by an
angle inversely proportional to the square root of the average photon number.
The field and the atomic dipole are phase-entangled. These manifestations of
photon graininess vanish at the classical limit. This experiment opens the way
to studies of large Schrodinger cat states at the quantum-classical boundary
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