1,275 research outputs found
Interference of Spontaneous Emission of Light from two Solid-State Atomic Ensembles
We report an interference experiment of spontaneous emission of light from
two distant solid-state ensembles of atoms that are coherently excited by a
short laser pulse. The ensembles are Erbium ions doped into two LiNbO3 crystals
with channel waveguides, which are placed in the two arms of a Mach-Zehnder
interferometer. The light that is spontaneously emitted after the excitation
pulse shows first-order interference. By a strong collective enhancement of the
emission, the atoms behave as ideal two-level quantum systems and no which-path
information is left in the atomic ensembles after emission of a photon. This
results in a high fringe visibility of 95%, which implies that the observed
spontaneous emission is highly coherent
Orbital Control on Carbonate-Lignite Cycles in the Ptolemais Basin, Northern Greece - An Integrated Stratigraphic Approach
Interference of multi-mode photon echoes generated in spatially separated solid-state atomic ensembles
High-visibility interference of photon echoes generated in spatially
separated solid-state atomic ensembles is demonstrated. The solid state
ensembles were LiNbO waveguides doped with Erbium ions absorbing at 1.53
m. Bright coherent states of light in several temporal modes (up to 3) are
stored and retrieved from the optical memories using two-pulse photon echoes.
The stored and retrieved optical pulses, when combined at a beam splitter, show
almost perfect interference, which demonstrates both phase preserving storage
and indistinguishability of photon echoes from separate optical memories. By
measuring interference fringes for different storage times, we also show
explicitly that the visibility is not limited by atomic decoherence. These
results are relevant for novel quantum repeaters architectures with photon echo
based multimode quantum memories
Universal description of S-wave meson spectra in a renormalized light-cone QCD-inspired model
A light-cone QCD-inspired model, with the mass squared operator consisting of
a harmonic oscillator potential as confinement and a Dirac-delta interaction,
is used to study the S-wave meson spectra. The two parameters of the harmonic
potential and quark masses are fixed by masses of rho(770), rho(1450), J/psi,
psi(2S), K*(892) and B*. We apply a renormalization method to define the model,
in which the pseudo-scalar ground state mass fixes the renormalized strength of
the Dirac-delta interaction. The model presents an universal and satisfactory
description of both singlet and triplet states of S-wave mesons and the
corresponding radial excitations.Comment: RevTeX, 17 pages, 7 eps figures, to be published in Phys. Rev.
The structure of hot gas in Cepheus B
By observing radiation-affected gas in the Cepheus B molecular cloud we probe
whether the sequential star formation in this source is triggered by the
radiation from newly formed stars. We used the dual band receiver GREAT onboard
SOFIA to map [C II] and CO 13--12 and 11--10 in Cep B and compared the spatial
distribution and the spectral profiles with complementary ground-based data of
low- transitions of CO isotopes, atomic carbon, and the radio continuum. The
interaction of the radiation from the neighboring OB association creates a
large photon-dominated region (PDR) at the surface of the molecular cloud
traced through the photoevaporation of C^+. Bright internal PDRs of hot gas are
created around the embedded young stars, where we detect evidence of the
compression of material and local velocity changes; however, on the global
scale we find no indications that the dense molecular material is dynamically
affected.Comment: Accepted for publication in A&A (SOFIA/GREAT special issue
Measurement of ultrashort bi-photon correlation times with an integrated two-colour broadband SU(1,1)-interferometer
The bi-photon correlation time, a measure for the conditional uncertainty in
the temporal arrival of two photons from a photon pair source, is a key
performance identifier for many quantum spectroscopy applications, with shorter
correlation times typically yielding better performance. Furthermore, it
provides fundamental insight into the effects of dispersion on the bi-photon
state. Here, we retrieve ultrashort bi-photon correlation times of around
by measuring simultaneously spectral and temporal
interferograms at the output of an SU(1,1) interferometer based on an
integrated broadband parametric down-conversion source in a
waveguideComment: 8 pages, 5 figure
Baryon spectra with instanton induced forces
Except the vibrational excitations of and mesons, the main features
of spectra of mesons composed of quarks , , and can be quite well
described by a semirelativistic potential model including instanton induced
forces. The spectra of baryons composed of the same quarks is studied using the
same model. The results and the limitations of this approach are described.
Some possible improvements are suggested.Comment: 5 figure
The Inception of Star Cluster Formation Revealed by [CII] Emission Around an Infrared Dark Cloud
We present SOFIA-upGREAT observations of [CII] emission of Infrared Dark
Cloud (IRDC) G035.39-00.33, designed to trace its atomic gas envelope and thus
test models of the origins of such clouds. Several velocity components of [CII]
emission are detected, tracing structures that are at a wide range of distances
in the Galactic plane. We find a main component that is likely associated with
the IRDC and its immediate surroundings. This strongest emission component has
a velocity similar to that of the CO(2-1) emission of the IRDC, but
offset by and with a larger velocity width of
. The spatial distribution of the [CII] emission of
this component is also offset predominantly to one side of the dense
filamentary structure of the IRDC. The CII column density is estimated to be of
the order of . We compare these results to
the [CII] emission from numerical simulations of magnetized, dense gas
filaments formed from giant molecular cloud (GMC) collisions, finding similar
spatial and kinematic offsets. These observations and modeling of [CII] add
further to the evidence that IRDC G035.39-00.33 has been formed by a process of
GMC-GMC collision, which may thus be an important mechanism for initiating star
cluster formation.Comment: 5 pages, 4 figures, submitted to MNRAS Letter
FMNH2-dependent monooxygenases initiate catabolism of sulfonamides in Microbacterium sp. strain BR1 subsisting on sulfonamide antibiotics
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