2,428 research outputs found
Proposal for entangling remote micromechanical oscillators via optical measurements
We propose an experiment to create and verify entanglement between remote
mechanical objects by use of an optomechanical interferometer. Two optical
cavities, each coupled to a separate mechanical oscillator, are coherently
driven such that the oscillators are laser cooled to the quantum regime. The
entanglement is induced by optical measurement and comes about by combining the
output from the two cavities to erase which-path information. It can be
verified through measurements of degrees of second-order coherence of the
optical output field. The experiment is feasible in the regime of weak
optomechanical coupling. Realistic parameters for the membrane-in-the-middle
geometry suggest entangled state lifetimes on the order of milliseconds.Comment: 4 pages, 2 figures + supplementary material (7 pages, 2 figs).
Updates in v2: New Eq. (7) and Fig. 1 - results unchanged. Added
supplementary material with various details. Updates in v3: Minor changes,
journal ref. adde
Modulational instability of partially coherent signals in electrical transmission lines
We present an investigation of the modulational instability of partially
coherent signals in electrical transmission lines. Starting from the modified
Ginzburg-Landau equations and the Wigner-Moyal representation, we derive a
nonlinear dispersion relation for the modulational instability. It is found
that the effect of signal broadbandness reduces the growth rate of the
modulational instability.Comment: 5 pages, 1 figure, to appear in Physical Review
Propagation of nonclassical light through an absorbing and dispersive slab
We calculate the effects of perpendicular propagation through a dispersive and absorbing dielectric slab at arbitrary temperatures on specific nonclassical properties of an incident light field. The transmitted signal is assumed to be measured by a detector that receives radiation only from the direction normal to thr slab surfaces. Squeezing and nonclassical counting statistics of the transmitted light are evaluated for continuous-wave squeezed states incident on both sides of the slab. The degree of second-order coherence is instead evaluated for an N-photon incident pulse, and the effects of transmission through the slab on its antibunching are calculated. [S1050-2947(99)06701-3]
Effects of frequency correlation in linear optical entangling gate operated with independent photons
Bose-Einstein coalescence of independent photons at the surface of a beam
splitter is the physical process that allows linear optical quantum gates to be
built. When distinct parametric down-conversion events are used as an
independent photon source, distinguishability arises form the energy
correlation of each photon with its twin. We find that increasing the pump
bandwidth may help in improving the visibility of non-classical interference
and reaching a level of near perfect indistinguishability. PACS: 03.67.Mn,
42.65.Lm, 42.50.St.Comment: Replaced with published versio
Coherent flash of light emitted by a cold atomic cloud
When a resonant laser sent on an optically thick cold atomic cloud is
abruptly switched off, a coherent flash of light is emitted in the forward
direction. This transient phenomenon is observed due to the highly resonant
character of the atomic scatterers. We analyze quantitatively its
spatio-temporal properties and show very good agreement with theoretical
predictions. Based on complementary experiments, the phase of the coherent
field is reconstructed without interferometric tools.Comment: Submitted to Phys. Rev. Let
Broadening the bandwidth of entangled photons: a step towards the generation of extremely short biphotons
We demonstrate a technique that allows to fully control the bandwidth of
entangled photons independently of the frequency band of interest and of the
nonlinear crystal. We show that this technique allows to generate nearly
transform-limited biphotons with almost one octave of bandwidth (hundreds of
THz) which corresponds to correlation times of just a few femtoseconds. The
presented method becomes an enabling tool for attosecond entangled-photons
quantum optics. The technique can also be used to generate paired photons with
a very high degree of entanglement.Comment: 4 page
Backgrounds of squeezed relic photons and their spatial correlations
We discuss the production of multi-photons squeezed states induced by the
time variation of the (Abelian) gauge coupling constant in a string
cosmological context. Within a fully quantum mechanical approach we solve the
time evolution of the mean number of produced photons in terms of the squeezing
parameters and in terms of the gauge coupling. We compute the first (amplitude
interference) and second order (intensity interference) correlation functions
of the magnetic part of the photon background. The photons produced thanks to
the variation of the dilaton coupling are strongly bunched for the realistic
case where the growth of the dilaton coupling is required to explain the
presence of large scale magnetic fields and, possibly of a Faraday rotation of
the Cosmic Microwave Background.Comment: 9 pages in LaTex styl
On Wheeler's delayed-choice Gedankenexperiment and its laboratory realization
Here, we present an analysis and interpretation of the experiment performed
by Jacques et al. (2007 Science 315, 966), which represents a realization of
Wheeler's delayed-choice Gedankenexperiment. Our analysis is based on the
evolution of the photon state, since the photon enters into the Mach-Zehnder
interferometer with a removable beam-splitter until it exits. Given the same
incident photon state onto the output beam-splitter, BS_output, the photon's
state at the exit will be very different depending on whether BS_output is on
or off. Hence, the statistics of photon counts collected by the two detectors,
positioned along orthogonal directions at the exit of the interferometer, is
also going to be very different in either case. Therefore, it is not that the
choice of inserting (on) or removing (off) a beam-splitter leads to a delayed
influence on the photon behavior before arriving at the beam-splitter, but that
such a choice influences the photon state at and after BS_output, i.e., after
it has exited from the Mach-Zehnder interferometer. The random on/off choice at
BS_output has no delayed effect on the photon to behave as a wave or a
corpuscle at the entrance and inside the interferometer, but influences the
subsequent evolution of the photon state incident onto BS_output.Comment: 7 pages, 4 figure
Economic evaluation of the treatment of grade II haemorrhoids : a comparison of stapled haemorrhoidopexy and rubber band ligation.
The definitive version is available at www3.interscience.wiley.comPeer reviewedPostprin
Damped Population Oscillation in a Spontaneously Decaying Two-Level Atom Coupled to a Monochromatic Field
We investigate the time evolution of atomic population in a two-level atom
driven by a monochromatic radiation field, taking spontaneous emission into
account. The Rabi oscillation exhibits amplitude damping in time caused by
spontaneous emission. We show that the semiclassical master equation leads in
general to an overestimation of the damping rate and that a correct
quantitative description of the damped Rabi oscillation can thus be obtained
only with a full quantum mechanical theory.Comment: 5 pages, 5 figure
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