2,529 research outputs found
Nonseparability and squeezing of continuous polarization variables
The impact of the operator-valued commutator on nonclassical properties of
continuous polarization variables is discussed. The definition of polarization
squeezing is clarified to exclude those squeezed states which do not contain
any new physics beyond quadrature squeezing. We present a consistent derivation
of the general nonseparability criterion for the continuous variables with the
operator-valued commutator, and apply it to the polarization variables.Comment: Replaced with revised version, more explanations included, Appendix
adde
The Bragg regime of the two-particle Kapitza-Dirac effect
We analyze the Bragg regime of the two-particle Kapitza-Dirac arrangement,
completing the basic theory of this effect. We provide a detailed evaluation of
the detection probabilities for multi-mode states, showing that a complete
description must include the interaction time in addition to the usual
dimensionless parameter w. The arrangement can be used as a massive
two-particle beam splitter. In this respect, we present a comparison with
Hong-Ou-Mandel-type experiments in quantum optics. The analysis reveals the
presence of dips for massive bosons and a differentiated behavior of
distinguishable and identical particles in an unexplored scenario. We suggest
that the arrangement can provide the basis for symmetrization verification
schemes
Correlated two-photon scattering in cavity optomechanics
We present an exact analytical solution of the two-photon scattering in a
cavity optomechanical system. This is achieved by solving the quantum dynamics
of the total system, including the optomechanical cavity and the cavity-field
environment, with the Laplace transform method. The long-time solution reveals
detailed physical processes involved as well as the corresponding resonant
photon frequencies. We characterize the photon correlation induced in the
scattering process by calculating the two-photon joint spectrum of the
long-time state. Clear evidence for photon frequency anti-correlation can be
observed in the joint spectrum. In addition, we calculate the equal-time
second-order correlation function of the cavity photons. The results show that
the radiation pressure coupling can induce photon blockade effect, which is
strongly modulated by the phonon sideband resonance. In particular, we obtain
an explicit expression of optomechanical coupling strength determining these
sideband modulation peaks based on the two-photon resonance condition.Comment: 10 pages, 6 figure
Quantum interference and entanglement induced by multiple scattering of light
We report on the effects of quantum interference induced by transmission of
an arbitrary number of optical quantum states through a multiple scattering
medium. We identify the role of quantum interference on the photon correlations
and the degree of continuous variable entanglement between two output modes. It
is shown that the effect of quantum interference survives averaging over all
ensembles of disorder and manifests itself as increased photon correlations
giving rise to photon anti-bunching. Finally, the existence of continuous
variable entanglement correlations in a volume speckle pattern is predicted.
Our results suggest that multiple scattering provides a promising way of
coherently interfering many independent quantum states of light of potential
use in quantum information processing.Comment: 5 pages including 4 figure
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
Interference of an Array of Independent Bose-Einstein Condensates
Interference of an array of independent Bose-Einstein condensates, whose
experiment has been performed recently, is theoretically studied in detail.
Even if the number of the atoms in each gas is kept finite and the phases of
the gases are not well defined, interference fringes are observed on each
snapshot. The statistics of the snapshot interference patterns, i.e., the
average fringe amplitudes and their fluctuations (covariance), are computed
analytically, and concise formulas for their asymptotic values for long time of
flight are derived. Processes contributing to these quantities are clarified
and the relationship with the description on the basis of the symmetry-breaking
scenario is revealed.Comment: 13 pages, 3 figure
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
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]
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