1,146 research outputs found
Photon correlations in a two-site non-linear cavity system under coherent drive and dissipation
We calculate the normalized second-order correlation function for a system of
two tunnel-coupled photonic resonators, each one exhibiting a single-photon
nonlinearity of the Kerr type. We employ a full quantum formulation: the master
equation for the model, which takes into account both a coherent continuous
drive and radiative as well as non-radiative dissipation channels, is solved
analytically in steady state through a perturbative approach, and the results
are compared to exact numerical simulations. The degree of second-order
coherence displays values between 0 and 1, and divides the diagram identified
by the two energy scales of the system - the tunneling and the nonlinear Kerr
interaction - into two distinct regions separated by a crossover. When the
tunneling term dominates over the nonlinear one, the system state is
delocalized over both cavities and the emitted light is coherent. In the
opposite limit, photon blockade sets in and the system shows an insulator-like
state with photons locked on each cavity, identified by antibunching of emitted
light.Comment: 9 pages, 4 figures, to appear in Phys. Rev.
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
Generating functions for generalized binomial distributions
In a recent article a generalization of the binomial distribution associated
with a sequence of positive numbers was examined. The analysis of the
nonnegativeness of the formal expressions was a key-point to allow to give them
a statistical interpretation in terms of probabilities. In this article we
present an approach based on generating functions that solves the previous
difficulties: the constraints of nonnegativeness are automatically fulfilled, a
complete characterization in terms of generating functions is given and a large
number of analytical examples becomes available.Comment: PDFLaTex, 27 pages, 5 figure
Squeezed Phonon States: Modulating Quantum Fluctuations of Atomic Displacements
We study squeezed quantum states of phonons, which allow the possibility of
modulating the quantum fluctuations of atomic displacements below the
zero-point quantum noise level of coherent phonon states. We calculate the
corresponding expectation values and fluctuations of both the atomic
displacement and the lattice amplitude operators, and also investigate the
possibility of generating squeezed phonon states using a three-phonon
parametric amplification process based on phonon-phonon interactions.
Furthermore, we also propose a detection scheme based on reflectivity
measurements.Comment: 4 pages, RevTeX. The previous entry had a wrong page number in the
Journal-ref fiel
Quantum Interference of Tunably Indistinguishable Photons from Remote Organic Molecules
We demonstrate two-photon interference using two remote single molecules as
bright solid-state sources of indistinguishable photons. By varying the
transition frequency and spectral width of one molecule, we tune and explore
the effect of photon distinguishability. We discuss future improvements on the
brightness of single-photon beams, their integration by large numbers on chips,
and the extension of our experimental scheme to coupling and entanglement of
distant molecules
Direct experimental evidence of free fermion antibunching
Fermion antibunching was observed on a beam of free noninteracting neutrons.
A monochromatic beam of thermal neutrons was first split by a graphite single
crystal, then fed to two detectors, displaying a reduced coincidence rate. The
result is a fermionic complement to the Hanbury Brown and Twiss effect for
photons.Comment: 4 pages, 2 figure
Long-range surface plasmon polariton excitation at the quantum level
We provide the quantum mechanical description of the excitation of long-range
surface plasmon polaritons (LRSPPs) on thin metallic strips. The excitation
process consists of an attenuated-reflection setup, where efficient
photon-to-LRSPP wavepacket-transfer is shown to be achievable. For calculating
the coupling, we derive the first quantization of LRSPPs in the polaritonic
regime. We study quantum statistics during propagation and characterize the
performance of photon-to-LRSPP quantum state transfer for single-photons,
photon-number states and photonic coherent superposition states.Comment: 9 pages, 6 figures, RevTeX4; Accepted versio
Stability of 1-D Excitons in Carbon Nanotubes under High Laser Excitations
Through ultrafast pump-probe spectroscopy with intense pump pulses and a wide
continuum probe, we show that interband exciton peaks in single-walled carbon
nanotubes (SWNTs) are extremely stable under high laser excitations. Estimates
of the initial densities of excitons from the excitation conditions, combined
with recent theoretical calculations of exciton Bohr radii for SWNTs, suggest
that their positions do not change at all even near the Mott density. In
addition, we found that the presence of lowest-subband excitons broadens all
absorption peaks, including those in the second-subband range, which provides a
consistent explanation for the complex spectral dependence of pump-probe
signals reported for SWNTs.Comment: 4 pages, 4 figure
Noncovariant gauge fixing in the quantum Dirac field theory of atoms and molecules
Starting from the Weyl gauge formulation of quantum electrodynamics (QED),
the formalism of quantum-mechanical gauge fixing is extended using techniques
from nonrelativistic QED. This involves expressing the redundant gauge degrees
of freedom through an arbitrary functional of the gauge-invariant transverse
degrees of freedom. Particular choices of functional can be made to yield the
Coulomb gauge and Poincar\'{e} gauge representations. The Hamiltonian we derive
therefore serves as a good starting point for the description of atoms and
molecules by means of a relativistic Dirac field. We discuss important
implications for the ontology of noncovariant canonical QED due to the gauge
freedom that remains present in our formulation.Comment: 8 pages, 0 figure
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