401 research outputs found
Properties of bright squeezed vacuum at increasing brightness
A bright squeezed vacuum (BSV) is a nonclassical macroscopic state of light, which is generated through high-gain parametric down-conversion or four-wave mixing. Although the BSV is an important tool in quantum optics and has a lot of applications, its theoretical description is still not complete. In particular, the existing description in terms of Schmidt modes with gain-independent shapes fails to explain the spectral broadening observed in the experiment as the mean number of photons increases. Meanwhile, the semiclassical description accounting for the broadening does not allow us to decouple the intermodal photon-number correlations. In this work, we present a new generalized theoretical approach to describe the spatial properties of a multimode BSV. In the multimode case, one has to take into account the complicated interplay between all involved modes: each plane-wave mode interacts with all other modes, which complicates the problem significantly. The developed approach is based on exchanging the (k, t ) and (ω, z) representations and solving a system of integrodifferential equations. Our approach predicts correctly the dynamics of the Schmidt modes and the broadening of the angular distribution with the increase in the BSV mean photon number due to a stronger pumping. Moreover, the model correctly describes various properties of a widely used experimental configuration with two crystals and an air gap between them, namely, an SU(1,1) interferometer. In particular, it predicts the narrowing of the intensity distribution, the reduction and shift of the side lobes, and the decline in the interference visibility as the mean photon number increases due to stronger pumping. The presented experimental results confirm the validity of the new approach. The model can be easily extended to the case of the frequency spectrum, frequency Schmidt modes, and other experimental configurations
Projective filtering of a single spatial radiation eigenmode
Lossless filtering of a single coherent (Schmidt) mode from spatially
multimode radiation is a problem crucial for optics in general and for quantum
optics in particular. It becomes especially important in the case of
nonclassical light that is fragile to optical losses. An example is bright
squeezed vacuum generated via high-gain parametric down conversion or four-wave
mixing. Its highly multiphoton and multimode structure offers a huge increase
in the information capacity provided that each mode can be addressed
separately. However, the nonclassical signature of bright squeezed vacuum,
photon-number correlations, are highly susceptible to losses. Here we
demonstrate lossless filtering of a single spatial Schmidt mode by projecting
the spatial spectrum of bright squeezed vacuum on the eigenmode of a
single-mode fiber. Moreover, we show that the first Schmidt mode can be
captured by simply maximizing the fiber-coupled intensity. Importantly, the
projection operation does not affect the targeted mode and leaves it usable for
further applications.Comment: 10 pages, 9 figure
Grain boundary assembly in a 316 L steel produced by selective laser melting and annealing
The effect of recrystallization annealing on the grain boundary assembly of a 316 L-type austenitic stainless steel produced by selective laser melting was studie
Semiclassical description of multiphoton processes
We analyze strong field atomic dynamics semiclassically, based on a full
time-dependent description with the Hermann-Kluk propagator. From the
properties of the exact classical trajectories, in particular the accumulation
of action in time, the prominent features of above threshold ionization (ATI)
and higher harmonic generation (HHG) are proven to be interference phenomena.
They are reproduced quantitatively in the semiclassical approximation.
Moreover, the behavior of the action of the classical trajectories supports the
so called strong field approximation which has been devised and postulated for
strong field dynamics.Comment: 10 pages, 11 figure
Properties of Neutral Charmed Mesons in Proton--Nucleus Interactions at 70 GeV
The results of treatment of data obtained in the SERP-E-184experiment
"Investigation of mechanisms of the production of charmed particles in
proton-nucleus interactions at 70 GeV and their decays" by irradiating the
active target of the SVD-2 facility consisting of carbon, silicon, and lead
plates, are presented. After separating a signal from the two-particle decay of
neutral charmed mesons and estimating the cross section for charm production at
a threshold energy {\sigma}(c\v{c})=7.1 \pm 2.4(stat.) \pm 1.4(syst.)
\mub/nucleon, some properties of D mesons are investigated. These include the
dependence of the cross section on the target mass number (its A dependence);
the behavior of the differential cross sections d{\sigma}/dpt2 and
d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical
variables xF, pt2, and plab. The experimental results in question are compared
with predictions obtained on the basis of the FRITIOF7.02 code.Comment: 9 pages, 9 figures,3 table
Observation of narrow baryon resonance decaying into in pA-interactions at with SVD-2 setup
SVD-2 experiment data have been analyzed to search for an exotic baryon
state, the -baryon, in a decay mode at on IHEP
accelerator. The reaction with a limited multiplicity was
used in the analysis. The invariant mass spectrum shows a resonant
structure with and . The statistical significance of this peak was estimated to be of . The mass and width of the resonance is compatible with the recently
reported - baryon with positive strangeness which was predicted as an
exotic pentaquark () baryon state. The total cross section for
production in pN-interactions for was estimated to be
and no essential deviation from A-dependence for inelastic
events was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some
references added, minor typos correcte
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