21,620 research outputs found
Photon-Photon Correlations as a Probe of Vacuum Induced Coherence Effects
We present new experimental implications of the effects of vacuum induced
coherence on the photon -photon correlation in the pi-polarized fluorescence in
j = 1/2 to j = 1/2 transition. These effects should be thus observable in
measurements of photon statistics in for example Hg and Ba ion traps.Comment: 7 pages, 6 figures, submitted to Physical Review
Inseparability inequalities for higher-order moments for bipartite systems
There are several examples of bipartite entangled states of continuous
variables for which the existing criteria for entanglement using the
inequalities involving the second order moments are insufficient. We derive new
inequalities involving higher order correlation, for testing entanglement in
non-Gaussian states. In this context we study an example of a non-Gaussian
state, which is a bipartite entangled state of the form .
Our results open up an avenue to search for new inequalities to test
entanglement in non-Gaussian states.Comment: 7 pages, Submitte
Mesoscopic superpositions of states - approach to classicality and diagonalization in coherent state basis
I consider the interaction of a superposition of mesoscopic coherent states
and its approach to a mixed state as a result of a suitably controlled
environment. I show how the presence of a gain medium in a cavity can lead to
diagonalization in coherent state basis in contrast to the standard model of
decoherence. I further show how the new model of decoherence can lead to the
generation of ordered quasi distributions.Comment: 10 pages, two figure pages, RevTe
Nonclassical Correlation of Polarization Entangled Photons in a Biexciton-Exciton Cascade
We develop a theoretical model to study the Intensity-Intensity correlation
of polarization entangled photons emitted in a biexciton-exciton cascade. We
calculate the degree of correlation and show how polarization correlation are
affected by the presence of dephasing and energy level splitting of the
excitonic states. Our theoretical calculations are in agreement with the recent
observation of polarization dependent Intensity-Intensity correlations from a
single semiconductor quantum dot [R. M. Stevenson et. al., Nature 439, 179
(2006)] . Our model can be extended to study polarization entangled photon
emission in coupled quantum dot systems
Magneto-optical rotation of spectrally impure fields and its nonlinear dependence on optical density
We calculate magneto-optical rptation of spectrally impure fileds in an
optically thick cold atmic medium. We show that the spectral impurity leads to
non-linear dependence of the rotation angle on optical density. Using our
calculations, we provide a quanttative analysis of the recent experimental
results of G. Labeyrie et al. [Phys. Rev. A 64, 033402 (2001)] using cold
Rb atoms.Comment: 6 pages, 5 Figures, ReVTeX4, Submitted to PR
Measuring arbitrary-order coherences: Tomography of single-mode multiphoton polarization-entangled states
A scheme is discussed for measuring Nth-order coherences of two orthogonally
polarized light fields in a single spatial mode at very limited experimental
cost. To implement the scheme, the only measurements needed are the Nth-order
intensity moments after the light beam has passed through two quarter-wave
plates, one half-wave plate, and a polarizing beam splitter for specific
settings of the wave plates. It is shown that this method can be applied for
arbitrarily large N. A set of explicit values is given for the settings of the
wave plates, constituting an optimal measurement of the Nth-order coherences
for any N. For Fock states the method introduced here corresponds to a full
state tomography. Applications of the scheme to systems other than polarization
optics are discussed.Comment: 6 pages, 1 figure, 1 table, published versio
Nonclassical Imaging for a quantum search of trapped ions
We discuss a simple search problem which can be pursued with different
methods, either on a classical or on a quantum basis. The system is represented
by a chain of trapped ions. The ion to be searched is a member of that chain,
consists, however, of an isotopic species different to the others. It is shown
that the classical imaging may lead as fast to the final result as the quantum
imaging. However, for the discussed case the quantum method gives more
flexibility and higher precision when the number of ions considered in the
chain is increasing. In addition, interferences are observable even when the
distances between the ions is smaller than half a wavelength of the incident
light.Comment: 5 pages, 5 figure
Analysis of MAGSAT and surface data of the Indian region
Techniques and significant results of an analysis of MAGSAT and surface data of the Indian region are described. Specific investigative tasks included: (1) use of the multilevel data at different altitudes to develop a model for variation of magnetic anomaly with altitude; (2) development of the regional model for the description of main geomagnetic field for the Indian sub-continent using MAGSAT and observatory data; (3) development of regional mathematical model of secular variations over the Indian sub-continent; and (4) downward continuation of the anomaly field obtained from MAGSAT and its combination with the existing observatory data to produce a regional anomaly map for elucidating tectonic features of the Indian sub-continent
Heisenberg limited Sagnac interferometry
We show how the entangled photons produced in parametric down conversion can
be used to improve the sensitivity of a Sagnac interferometer. Two-photon and
four-photon coincidences increases the sensitivity by a factor of two and four
respectively. Our results apply to sources with arbitrary pumping and squeezing
parameters.Comment: 11 pages, 5 figure
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