329 research outputs found
Selective excitations of a Kerr-nonlinear resonator: exactly solvable approach
We study Kerr nonlinear resonators (KNR) driven by a continuous wave field in
quantum regimes where strong Kerr interactions give rise to selective resonant
excitations of oscillatory modes. We use an exact quantum theory of KNR in the
framework of the Fokker-Planck equation without any quantum state truncation or
perturbation procedure. This approach allows non-perturbative consideration of
KNR for various quantum operational regimes including cascaded processes
between oscillatory states. We focus on understanding of multi-photon
non-resonant and selective resonant excitations of introcavity mode depending
on the detuning, the amplitude of the driving field and the strength of
nonlinearity. The analysis is provided on the base of photon number
distributions, the photon-number correlation function and the Wigner function.Comment: 8 pages, 9 figure
Quantum statistics in time-modulated exciton-photon system
We consider a system consisting of a large individual quantum dot with
excitonic resonance coupled to a single mode photonic cavity in the nonlinear
regime when exciton- exciton interaction becomes important. We show that in the
presence of time-modulated external coherent pumping the system demonstrates
essentially non classical behavior reflected in sub-Poissonian statistics of
exciton- and photon-modes and the Wigner functions with negative values in
phase-space for time-intervals exceeding the characteristic time of dissipative
processes, . It is shown that these results are cardinally
different from the analogous results in the regime of the monomode
continues-wave (cw) excitation.Comment: 8 pages, 6 figure
Phase-locking at low-level of quanta
We discuss phase-locking phenomena at low-level of quanta for parametrically
driven nonlinear Kerr resonator (PDNR) in strong quantum regime. Oscillatory
mode of PDNR is created in the process of a degenerate down-conversion of
photons under interaction with a train of external Gaussian pulses. We
calculate the Wigner functions of cavity mode showing two-fold symmetry in
phase space and analyse formation of phase-locked states in the regular as well
as the quantum chaotic regime.Comment: 6 pages, 4 figure
Bistability and chaos at low-level of quanta
We study nonlinear phenomena of bistability and chaos at a level of few
quanta. For this purpose we consider a single-mode dissipative oscillator with
strong Kerr nonlinearity with respect to dissipation rate driven by a
monochromatic force as well as by a train of Gaussian pulses. The quantum
effects and decoherence in oscillatory mode are investigated on the framework
of the purity of states and the Wigner functions calculated from the master
equation. We demonstrate the quantum chaotic regime by means of a comparison
between the contour plots of the Wigner functions and the strange attractors on
the classical Poincar\'e section. Considering bistability at low-limit of
quanta, we analyze what is the minimal level of excitation numbers at which the
bistable regime of the system is displayed? We also discuss the formation of
oscillatory chaotic regime by varying oscillatory excitation numbers at ranges
of few quanta. We demonstrate quantum-interference phenomena that are assisted
hysteresis-cycle behavior and quantum chaos for the oscillator driven by the
train of Gaussian pulses as well as we establish the border of
classical-quantum correspondence for chaotic regimes in the case of strong
nonlinearities.Comment: 10 pages, 14 figure
Clinical Endoscopic and Histological Characteristics of Helicobacter Pylori Positive and Negative Armenian Children with Recurrent Abdominal Pain and/or Dyspepsia
Recurrent abdominal pain (RAP) and dyspepsia are common complaints in children. These symptoms are often associated with Helicobacter pylori (Hp) infection. The aim of the present study was to prospectively analyze clinical, endoscopic, and histological characteristics of Hp+ and Hp- children with RAP and/or dyspepsia. Patients aged 2-18 years with RAP and/or dyspepsia, referred for an upper endoscopy to Arabkir Medical Center - Institute of Child and Adolescent Health (Arabkir MC-ICAH) from November 2015 to December 2017, were involved in the study. Histology was assessed according to the updated Sydney system. Gastric and duodenal specimens were stained by modified Giemsa staining for Hp infection. One antral biopsy was cultured in Hp selective media. 150 patients were included into the study: 70.7% Hp+, 29.3% Hp-. Nausea and vomiting were significantly more common in Hp+ patients (p<0.05). Gastric nodularity (p=0.02), erosions in the stomach (p=0.056), and duodenal erosions (p=0.019) were more common in Hp+. Chronic active (p=0.027) and non-active gastritis (p=0.002), cumulative findings of metaplasia/dysplasia/atrophy in the stomach (p=0.014) and chronic non-active duodenitis (p=0.016), were significantly more common in Hp+ patients. Hp infection prevalence is high in Armenian children with dyspepsia and/or RAP. Clinical symptoms, endoscopic findings, and histopathological findings were significantly different in Hp+ patients as compared to Hp- patients
Dissipative Chaos in Quantum Distributions
We discuss some problems of dissipative chaos for open quantum systems in the
framework of semiclassical and quantum distributions. For this goal, we propose
a driven nonlinear oscillator with time-dependent coefficients, i.e. with
time-dependent Kerr-nonlinearity and time-modulated driving field. This model
showing both regular and chaotic dynamics in the classical limit is realized in
several experimental schemes. Quantum dissipative chaos is analyzed on the base
of numerical method of quantum trajectories. Three quantities are studied: the
Wigner function of oscillatory mode from the point of view of quantum-assemble
theory and both semiclassical Poincare section and quantum Poincare section
calculated on a single quantum trajectory. The comparatively analysis of these
distributions for various operational chaotic regimes of the models is
performed, as well as scaling invariance in dissipative chaos and quantum
interference effects assisted by chaos are discussed.Comment: 17 pages, 3 figures, proceeding of Modern Optics And Photonic
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