Photon waiting time distributions: a keyhole into dissipative quantum chaos

Open quantum systems can exhibit complex states, which classification and quantification is still not well resolved. The Kerr-nonlinear cavity, periodically modulated in time by coherent pumping of the intra-cavity photonic mode, is one of the examples. Unraveling the corresponding Markovian master equation into an ensemble of quantum trajectories and employing the recently proposed calculation of quantum Lyapunov exponents [I.I. Yusipov {\it et al.}, Chaos {\bf 29}, 063130 (2019)], we identify `chaotic' and `regular' regimes there. In particular, we show that chaotic regimes manifest an intermediate power-law asymptotics in the distribution of photon waiting times. This distribution can be retrieved by monitoring photon emission with a single-photon detector, so that chaotic and regular states can be discriminated without disturbing the intra-cavity dynamics.Comment: 7 pages, 5 figure

Control of a single-particle localization in open quantum systems

We investigate the possibility to control localization properties of the asymptotic state of an open quantum system with a tunable synthetic dissipation. The control mechanism relies on the matching between properties of dissipative operators, acting on neighboring sites and specified by a single control parameter, and the spatial phase structure of eigenstates of the system Hamiltonian. As a result, the latter coincide (or near coincide) with the dark states of the operators. In a disorder-free Hamiltonian with a flat band, one can either obtain a localized asymptotic state or populate whole flat and/or dispersive bands, depending on the value of the control parameter. In a disordered Anderson system, the asymptotic state can be localized anywhere in the spectrum of the Hamiltonian. The dissipative control is robust with respect to an additional local dephasing.Comment: 6 pages, 5 figure

Localization in periodically modulated speckle potentials

Disorder in a 1D quantum lattice induces Anderson localization of the eigenstates and drastically alters transport properties of the lattice. In the original Anderson model, the addition of a periodic driving increases, in a certain range of the driving's frequency and amplitude, localization length of the appearing Floquet eigenstates. We go beyond the uncorrelated disorder case and address the experimentally relevant situation when spatial correlations are present in the lattice potential. Their presence induces the creation of an effective mobility edge in the energy spectrum of the system. We find that a slow driving leads to resonant hybridization of the Floquet states, by increasing both the participation numbers and effective widths of the states in the strongly localized band and decreasing values of these characteristics for the states in the quasi-extended band. Strong driving homogenizes the bands, so that the Floquet states loose compactness and tend to be spatially smeared. In the basis of the stationary Hamiltonian, these states retain localization in terms of participation number but become de-localized and spectrum-wide in term of their effective widths. Signatures of thermalization are also observed.Comment: 6 pages, 3 figure

Localization in open quantum systems

In an isolated single-particle quantum system a spatial disorder can induce Anderson localization. Being a result of interference, this phenomenon is expected to be fragile in the face of dissipation. Here we show that dissipation can drive a disordered system into a steady state with tunable localization properties. This can be achieved with a set of identical dissipative operators, each one acting non-trivially only on a pair of neighboring sites. Operators are parametrized by a uniform phase, which controls selection of Anderson modes contributing to the state. On the microscopic level, quantum trajectories of a system in a localized steady regime exhibit intermittent dynamics consisting of long-time sticking events near selected modes interrupted by jumps between them.Comment: 5 pages, 5 figure

Lyapunov exponents of quantum trajectories beyond continuous measurements

Quantum systems interacting with their environments can exhibit complex non-equilibrium states that are tempting to be interpreted as quantum analogs of chaotic attractors. Yet, despite many attempts, the toolbox for quantifying dissipative quantum chaos remains very limited. In particular, quantum generalizations of Lyapunov exponent, the main quantifier of classical chaos, are established only within the framework of continuous measurements. We propose an alternative generalization which is based on the unraveling of a quantum master equation into an ensemble of so-called 'quantum jump' trajectories. These trajectories are not only a theoretical tool but a part of the experimental reality in the case of quantum optics. We illustrate the idea by using a periodically modulated open quantum dimer and uncover the transition to quantum chaos matched by the period-doubling route in the classical limit.Comment: 5 pages, 4 figure

The effect of alloying on the microstructure and mechanical properties of Mo-Fe-B boride hard alloys

Mo2FeB2 based cermets with different Cr and Ni contents were prepared by liquid phase sintering. The effects of Ni and Cr content on the microstructure, hardness and fracture toughness were investigated. The results reveal that alloying of cermet with nickel leads to formation of structure сharacterized by high austenite volume fraction and low ferrite conten

Biosynthesis of secreted ribonucleases of Bacillus intermedius and Bacillus circulans under nitrogen starvation

The level of biosynthesis of secreted guanyl-specific ribonucleases (RNases) of Bacillus intermedius (binases) and Bacillus circulans (RNases Bci) by recombinant B. subtilis strains increases under nitrogen starvation. The promoter of the binase gene carries the sequences homologous to the recognition sites of the regulatory protein TnrA, which regulates gene expression under growth limitation by nitrogen. Using the B. subtilis strain defective in protein TnrA, it has been shown that the regulatory protein TnrA is involved in the regulation of expression of the binase gene and the gene of RNase Bci. The TnrA regulation of expression of the RNase Bci gene is indirect, probably by means of the regulatory protein PucR. Thus, it has been established that at least two regulatory mechanisms activate the expression of the genes encoding the secreted RNases of spore-forming bacteria: a system of proteins homologous to the B. subtilis PhoP-PhoR, and regulation by a protein similar to the B. subtilis TnrA regulatory protein. © 2009 Pleiades Publishing, Ltd

Respiratory pathology in connective tissue dysplasia (Irterture review)

This article represents the literature review devoted to a problem of a respiratory pathology at heritable disorders of connective tissue. Historical aspects of the concept connective tissue dysplasia are given, the basic terminological and classification approaches including debatable are presented. General data about the lungs pathology at monogene genetic syndromes is cited. Results of researches on which basis diagnostic criteria of respiratory pathology have been allocated at widespread undifferentiated variants of a heritable disorders of connective tissue are analysed. It is shown that the condition of respiratory organs at a connective tissue dysplasia is defined morphofunctional changes of respiratory tracts and a pulmonary parenchyma and influence of various extrapulmonary factors. It is noticed that the majority of works has mainly descriptive character without attempt of carrying out of fundamental morphological and pathophysiological researches which would allow to explain respiratory pathology mechanisms.Данная статья представляет собой обзор литературы, посвященной проблеме поражения органов дыхания при наследственных нарушениях соединительной ткани. Освещены исторические аспекты становления концепции дисплазии соединительной ткани, представлены основные, в том числе дискуссионные, терминологические и классификационные подходы. Приведены обобщенные данные о патологии легких при моногенных генетических синдромах. Проанализированы результаты исследований, на основании которых были выделены диагностические критерии поражения респираторной системы при широко распространенных недифференцированных вариантах наследственного поражения соединительной ткани. Показано, что состояние органов дыхания при дисплазии соединительной ткани определяется как морфофункциональными изменениями дыхательных путей и легочной паренхимы, так и воздействием различных внелегочных факторов. Отмечено, что большинство работ носит преимущественно описательный характер без попытки изучения фундаментальных морфологических и патофизиологических механизмов развития того или иного вида бронхолегочной патологии

Solving the problem of credit defaults in retail sector

The article analyzes dynamics of the volume and annual rate of loan delinquency of the country’s population for intermediate quarter dates, compares default retail credit portfolios with similar portfolio of organizations, and determines the main reasons for appearance of population’s debts before banks. It is concluded that it is necessary for banks to focus on development of their own tools and technologies of payment recovery, related to determination of early problematic debt for the purpose of taking preventive measures for preventing the appearance of past-due debts, which is possible under the condition of investing money assets into own analytical and technological tools. An approach to segmentation of debts and factors that could be used as indicators in the process of accompanying and servicing of credits are offered.peer-reviewe

Role of a two-component ResD-ResE system in regulating the expression of guanyl-specific ribonuclease genes in Bacilli

The role of the two-component ResD-ResE signal transduction system in regulating the expression of guanyl-specific ribonuclease genes in bacilli has been studied. Proteins with homologies to the ResD and ResE regulatory proteins of Bacillus subtilis have been found in all sequenced genomes of Bacillus. It has been shown using the B. subtilis strains defective in genes of these proteins that the ResD-ResE signal transduction system positively regulates the expression of ribonuclease genes of B. intermedius, B. pumilus, and B. thuringiensis in cells of B. subtilis. The data obtained in this work speak for the fact that regulatory system similar to the two-component ResD-ResE signal transduction system of B. subtilis also functions in other representatives of the Bacillus genus. © 2008 Allerton Press, Inc