13 research outputs found
Three-photon states in nonlinear crystal superlattices
It has been a longstanding goal in quantum optics to realize controllable
sources generating joint multiphoton states, particularly, photon triplet with
arbitrary spectral characteristics. We demonstrate that such sources can be
realized via cascaded parametric down-conversion (PDC) in superlattice
structures of nonlinear and linear segments. We consider scheme that involves
two parametric processes: ,
under pulsed pump and investigate
spontaneous creation of photon triplet as well as generation of high-intensity
mode in intracavity three-photon splitting. We show preparation of
Greenberger-Horne-Zeilinger polarization entangled states in cascaded type-II
and type-I PDC in framework of consideration dual-grid structure that involves
two periodically-poled crystals. We demonstrate the method of compensation of
the dispersive effects in non-linear segments by appropriately chosen linear
dispersive segments of superlattice for preparation heralded joint states of
two polarized photons. In the case of intracavity three-photon splitting, we
concentrate on investigation of photon-number distributions, third-order
photon-number correlation function as well as the Wigner functions. These
quantities are observed both for short interaction time intervals and in over
transient regime, when dissipative effects are essential.Comment: 15 pages, 6 figure
Exactly solvable Ising--Heisenberg chain with triangular XXZ-Heisenberg plaquettes
A mixed Ising-Heisenberg spin system consisting of triangular XXZ-Heisenberg
spin clusters assembled into a chain by alternating with Ising spins
interacting to all three spins in the triangle is considered. The exact
solution of the model is given in terms of the generalized
decoration--iteration map and within the transfer-matrix technique. Exact
expressions for thermodynamic functions are derived. Ground state phase
diagrams, thermodynamic and magnetic properties of the system are examined.Comment: 16 pages, 12 figure
Chirped quasi-phase-matching with Gauss sums for production of biphotons
We study the theory of linearly chirped biphoton wave-packets produced in two
basic quasi-phase-matching configurations: chirped photonic-like crystals and
aperiodically poled crystals. The novelty is that these structures are
considered as definite assembles of nonlinear layers that leads to detailed
description of spontaneous parametric down-conversion (SPDC) processes through
the discrete Gauss sums. We demonstrate that biphoton spectra for chirped
photonic crystals involving a small number of layers consist from definite
well-resolved spectral lines. We also discuss the forming of broadband spectra
of signal (idler) waves in SPDC for both configurations as number of layers
increases as well as in dependence of chirping parameters .Comment: 7 pages, 3 figure
Lattice distortions in a sawtooth chain with Heisenberg and Ising bonds
An exactly solvable model of the sawtooth chain with Ising and Heisenberg
bonds and with coupling to lattice distortion for Heisenberg bonds is
considered in the magnetic field. Using the direct transfer-matrix formalism an
exact description of the thermodynamic functions is obtained. The ground state
phase diagrams for all regions of parameters values containing phases
corresponding to the magnetization plateaus at and 1/2 have been
obtained. Exact formulas for bond distortions for various ground states are
presented. A novel mechanism of magnetization plateau stabilization
corresponding to state is reported.Comment: 16 pages, 12 figure
Magnetic properties and concurrence for fluid 3He on kagome lattice
We present the results of magnetic properties and entanglement for kagome
lattice using Heisenberg model with two-, and three-site exchange interactions
in strong magnetic field. Kagome lattice correspond to the third layer of fluid
3He absorbed on the surface of graphite. The magnetic properties and
concurrence as a measure of pairwise thermal entanglement are studied by means
of variational mean-field like treatment based on Gibbs-Bogoliubov inequality.
The system exhibits different magnetic behaviors, depending on the values of
the exchange parameters (J2, J3). We have obtained the magnetization plateaus
at low temperatures. The central theme of the paper is the comparing the
entanglement and magnetic behavior for kagome lattice. We have found that in
the antiferromagnetic region behaviour of the concurrence coincides with the
magnetization one.Comment: Physics of Atomic Nuclei (accepted for publication) 201
THE DISORDERING EFFECT ON THE ONE-DIMENSIONAL APPERIODIC OPTICAL SUPER-LATTICE IN MULTI-FREQUENCY SHG
MULTI-FREQUENCY SECOND HARMONIC GENERATION IN IRREGULAR TWO DIMENSIONAL APERIODIC OPTICAL SUPERLATTICES
Prevalence of uncoupling protein one genetic polymorphisms and their relationship with cardiovascular and metabolic health.
Contribution of UCP1 single nucleotide polymorphisms (SNPs) to susceptibility for cardiometabolic pathologies (CMP) and their involvement in specific risk factors for these conditions varies across populations. We tested whether UCP1 SNPs A-3826G, A-1766G, Ala64Thr and A-112C are associated with common CMP and their risk factors across Armenia, Greece, Poland, Russia and United Kingdom. This case-control study included genotyping of these SNPs, from 2,283 Caucasians. Results were extended via systematic review and meta-analysis. In Armenia, GA genotype and A allele of Ala64Thr displayed ~2-fold higher risk for CMP compared to GG genotype and G allele, respectively (p0.05). Concluding, the studied SNPs could be associated with the most common CMP and their risk factors in some populations