1,312 research outputs found
Quantum Entanglement Initiated Super Raman Scattering
It has now been possible to prepare chain of ions in an entangled state and
thus question arises --- how the optical properties of a chain of entangled
ions differ from say a chain of independent particles. We investigate nonlinear
optical processes in such chains. We explicitly demonstrate the possibility of
entanglement produced super Raman scattering. Our results in contrast to
Dicke's work on superradiance are applicable to stimulated processes and are
thus free from the standard complications of multimode quantum electrodynamics.
Our results suggest the possibility of similar enhancement factors in other
nonlinear processes like four wave mixing.Comment: 4 pages, 1 figur
Thermal breakdown of coherent backscattering: a case study of quantum duality
We investigate coherent backscattering of light by two harmonically trapped
atoms in the light of quantitative quantum duality. Including recoil and
Doppler shift close to an optical resonance, we calculate the interference
visibility as well as the amount of which-path information, both for zero and
finite temperature.Comment: published version with minor changes and an added figur
Non-classical photon pair generation in atomic vapours
A scheme for the generation of non-classical pairs of photons in atomic
vapours is proposed. The scheme exploits the fact that the cross correlation of
the emission of photons from the extreme transitions of a four-level cascade
system shows anti-bunching which has not been reported earlier and which is
unlike the case of the three level cascade emission which shows bunching. The
Cauchy-Schwarz inequality which is the ratio of cross-correlation to the auto
correlation function in this case is estimated to be for
controllable time delay, and is one to four orders of magnitude larger compared
to previous experiments. The choice of Doppler free geometry in addition to the
fact that at three photon resonance the excitation/deexcitation processes occur
in a very narrow frequency band, ensures cleaner signals.Comment: 18 pages, 7 figure
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
Quantum Frequency Translation of Single-Photon States in Photonic Crystal Fiber
We experimentally demonstrate frequency translation of a nonclassical optical
field via the Bragg scattering four-wave mixing process in a photonic crystal
fiber (PCF). The high nonlinearity and the ability to control dispersion in PCF
enable efficient translation between photon channels within the visible
to-near-infrared spectral range, useful in quantum networks. Heralded single
photons at 683 nm were translated to 659 nm with an efficiency of percent. Second-order correlation measurements on the 683-nm and 659-nm
fields yielded and respectively, showing the nonclassical nature of both fields.Comment: 5 pages, 3 figure
Strong extinction of a laser beam by a single molecule
We present an experiment where a single molecule strongly affects the
amplitude and phase of a laser field emerging from a subwavelength aperture. We
achieve a visibility of -6% in direct and +10% in cross-polarized detection
schemes. Our analysis shows that a close to full extinction should be possible
using near-field excitation.Comment: 5 pages, 4 figures, submitted to PR
Nonlinear Interferometry via Fock State Projection
We use a photon-number resolving detector to monitor the photon number
distribution of the output of an interferometer, as a function of phase delay.
As inputs we use coherent states with mean photon number up to seven. The
postselection of a specific Fock (photon-number) state effectively induces
high-order optical non-linearities. Following a scheme by Bentley and Boyd
[S.J. Bentley and R.W. Boyd, Optics Express 12, 5735 (2004)] we explore this
effect to demonstrate interference patterns a factor of five smaller than the
Rayleigh limit.Comment: 4 pages, 5 figure
Theory and it ab initio calculation of radiative lifetime of excitons in semiconducting carbon nanotubes
We present theoretical analysis and first-principles calculation of the
radiative lifetime of excitons in semiconducting carbon nanotubes. An intrinsic
lifetime of the order of 10 ps is computed for the lowest optically active
bright excitons. The intrinsic lifetime is however a rapid increasing function
of the exciton momentum. Moreover, the electronic structure of the nanotubes
dictates the existence of dark excitons nearby in energy to each bright
exciton. Both effects strongly influence measured lifetime. Assuming a thermal
occupation of bright and dark exciton bands, we find an effective lifetime of
the order of 10 ns at room temperature, in good accord with recent experiments.Comment: 12 pages, 3 figure
Canonical, squeezed and fermionic coherent states in a right quaternionic Hilbert space with a left multiplication on it
Using a left multiplication defined on a right quaternionic Hilbert space, we
shall demonstrate that various classes of coherent states such as the canonical
coherent states, pure squeezed states, fermionic coherent states can be defined
with all the desired properties on a right quaternionic Hilbert space. Further,
we shall also demonstrate squeezed states can be defined on the same Hilbert
space, but the noncommutativity of quaternions prevents us in getting the
desired results.Comment: Conference paper. arXiv admin note: text overlap with
arXiv:1704.02946; substantial text overlap with arXiv:1706.0068
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