700 research outputs found
Mean parity of single quantum excitation of some optical fields in thermal environments
The mean parity (the Wigner function at the origin) of excited binomial
states, excited coherent states and excited thermal states in thermal channel
is investigated in details. It is found that the single-photon excited binomial
state and the single-photon excited coherent state exhibit certain similarity
in the aspect of their mean parity in the thermal channel. We show the negative
mean parity can be regarded as an indicator of nonclassicality of single-photon
excitation of optical fields with a little coherence, especially for the
single-photon excited thermal states.Comment: 4 pages, 4 figures, RevTex4; PACS numbers: 42.50.Dv, 03.65.Yz,
05.40.Ca; Three typo errors have been correcte
Single-shot measurement of quantum optical phase
Although the canonical phase of light, which is defined as the complement of
photon number, has been described theoretically by a variety of distinct
approaches, there have been no methods proposed for its measurement. Indeed
doubts have been expressed about whether or not it is measurable. Here we show
how it is possible, at least in principle, to perform a single-shot measurement
of canonical phase using beam splitters, mirrors, phase shifters and
photodetectors.Comment: This paper was published in PRL in 2002 but, at the time, was not
placed on the archive. It is included now to make accessing this paper easie
Coherent and squeezed states of quantum Heisenberg algebras
Starting from deformed quantum Heisenberg Lie algebras some realizations are
given in terms of the usual creation and annihilation operators of the standard
harmonic oscillator. Then the associated algebra eigenstates are computed and
give rise to new classes of deformed coherent and squeezed states. They are
parametrized by deformed algebra parameters and suitable redefinitions of them
as paragrassmann numbers. Some properties of these deformed states also are
analyzed.Comment: 32 pages, 3 figure
Scaling and Duality in Semi-exclusive Processes
We discuss extending scaling and duality studies to semi-exclusive processes.
We show that semi-exclusive hard pion photoproduction should exhibit scaling
behavior in kinematic regions where the photon and pion both interact directly
with the same quark. We show that such kinematic regions exist. We also show
that the constancy with changing momentum transfer of the resonance
peak/scaling curve ratio, familiar for many resonances in deep inelastic
scattering, is also expected in the semi-exclusive case.Comment: 8 pages, 4 figures, submitted to Phys.Rev.
Theory Support for the Excited Baryon Program at the Jlab 12 GeV Upgrade
This document outlines major directions in theoretical support for the
measurement of nucleon resonance transition form factors at the JLab 12 GeV
upgrade with the CLAS12 detector. Using single and double meson production,
prominent resonances in the mass range up to 2 GeV will be studied in the range
of photon virtuality up to 12 GeV where quark degrees of freedom are
expected to dominate. High level theoretical analysis of these data will open
up opportunities to understand how the interactions of dressed quarks create
the ground and excited nucleon states and how these interactions emerge from
QCD. The paper reviews the current status and the prospects of QCD based model
approaches that relate phenomenological information on transition form factors
to the non-perturbative strong interaction mechanisms, that are responsible for
resonance formation.Comment: 52 pages, 19 figures, White Paper of the Electromagnetic N-N*
Transition Form Factor Workshop at Jefferson Lab, October 13-15, 2008,
Newport News, VA, US
Cosmological Perturbations of Quantum-Mechanical Origin and Anisotropy of the Microwave Background
Cosmological perturbations generated quantum-mechanically (as a particular
case, during inflation) possess statistical properties of squeezed quantum
states. The power spectra of the perturbations are modulated and the angular
distribution of the produced temperature fluctuations of the CMBR is quite
specific. An exact formula is derived for the angular correlation function of
the temperature fluctuations caused by squeezed gravitational waves. The
predicted angular pattern can, in principle, be revealed by the COBE-type
observations.Comment: 9 pages, WUGRAV-92-17 Accepted for Publication in Phys. Rev. Letters
(1993
Statistics of Raman-Active Excitations via Masurement of Stokes-Anti-Stokes Correlations
A general fundamental relation connecting the correlation of Stokes and
anti-Stokes modes to the quantum statistical behavior of vibration and pump
modes in Raman-active materials is derived. We show that under certain
conditions this relation can be used to determine the equilibrium number
variance of phonons.Time and temperature ranges for which such conditions can
be satisfied are studied and found to be available in todays' experimental
standards. Furthermore, we examine the results in the presence of multi-mode
pump as well as for the coupling of pump to the many vibration modes and
discuss their validity in these cases.Comment: 12 pages, 1 figure, accepted for publication in Phys.Rev.
States interpolating between number and coherent states and their interaction with atomic systems
Using the eigenvalue definition of binomial states we construct new
intermediate number-coherent states which reduce to number and coherent states
in two different limits. We reveal the connection of these intermediate states
with photon-added coherent states and investigate their non-classical
properties and quasi-probability distributions in detail. It is of interest to
note that these new states, which interpolate between coherent states and
number states, neither of which exhibit squeezing, are nevertheless squeezed
states. A scheme to produce these states is proposed. We also study the
interaction of these states with atomic systems in the framework of the
two-photon Jaynes-Cummings model, and describe the response of the atomic
system as it varies between the pure Rabi oscillation and the collapse-revival
mode and investigate field observables such as photon number distribution,
entropy and the Q-function.Comment: 26 pages, 29 EPS figures, Latex, Accepted for publication in J.Phys.
Approach to Perturbative Results in the N-Delta Transition
We show that constraints from perturbative QCD calculations play a role in
the nucleon to Delta(1232) electromagnetic transition even at moderate momentum
transfer scales. The pQCD constraints, tied to real photoproduction data and
unseparated resonance response functions, lead to explicit forms for the
helicity amplitudes wherein the E2/M1 ratio remains small at moderately large
momentum transfer.Comment: 4 pages, 2 figures, ReVTe
SU(2) and SU(1,1) algebra eigenstates: A unified analytic approach to coherent and intelligent states
We introduce the concept of algebra eigenstates which are defined for an
arbitrary Lie group as eigenstates of elements of the corresponding complex Lie
algebra. We show that this concept unifies different definitions of coherent
states associated with a dynamical symmetry group. On the one hand, algebra
eigenstates include different sets of Perelomov's generalized coherent states.
On the other hand, intelligent states (which are squeezed states for a system
of general symmetry) also form a subset of algebra eigenstates. We develop the
general formalism and apply it to the SU(2) and SU(1,1) simple Lie groups.
Complete solutions to the general eigenvalue problem are found in the both
cases, by a method that employs analytic representations of the algebra
eigenstates. This analytic method also enables us to obtain exact closed
expressions for quantum statistical properties of an arbitrary algebra
eigenstate. Important special cases such as standard coherent states and
intelligent states are examined and relations between them are studied by using
their analytic representations.Comment: LaTeX, 24 pages, 1 figure (compressed PostScript, available at
http://www.technion.ac.il/~brif/abstracts/AES.html ). More information on
http://www.technion.ac.il/~brif/science.htm
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