Dynamics Of Open Systems Research Articles

Experimental Investigation of Uncertainty Relations for Non-Hermitian Operators.

Uncertainty relations for Hermitian operators have been confirmed through many experiments. However, previous experiments have only tested the special case of non-Hermitian operators, i.e., uncertainty relations for unitary operators. In this study, we explore uncertainty relations for general non-Hermitian operators, which include Hermitian and unitary operators as special cases. We perform experiments with both real and complex non-Hermitian operators for qubit states, and confirm the validity of the uncertainty relations within the experimental error. Our results provide experimental evidence of uncertainty relations for non-Hermitian operators. Furthermore, our methods for realizing and measuring non-Hermitian operators are valuable in characterizing open-system dynamics and enhancing parameter estimation.

Adaptive variational simulation for open quantum systems

Emerging quantum hardware provides new possibilities for quantum simulation. While much of the research has focused on simulating closed quantum systems, the real-world quantum systems are mostly open. Therefore, it is essential to develop quantum algorithms that can effectively simulate open quantum systems. Here we present an adaptive variational quantum algorithm for simulating open quantum system dynamics described by the Lindblad equation. The algorithm is designed to build resource-efficient ansatze through the dynamical addition of operators by maintaining the simulation accuracy. We validate the effectiveness of our algorithm on both noiseless simulators and IBM quantum processors and observe good quantitative and qualitative agreement with the exact solution. We also investigate the scaling of the required resources with system size and accuracy and find polynomial behavior. Our results demonstrate that near-future quantum processors are capable of simulating open quantum systems.

The influence of Ohmic noise on the dynamics of three-spin open quantum system

The dynamics of open quantum systems under decoherence effects remain a hotly debated topic in the case of the practical deployment of quantum information processing. In this regard, we examine how the three-qubit mixed state is affected by changes in the cut-off frequency of the Ohmic spectral density in a harmonic reservoir. Specifically, the degree of quantum memory-assisted entropic uncertainty (QMA-EU), along with the entanglement, coherence, and purity of the system, is to be demonstrated. A thorough exercise is done to investigate any underlying relationship between the three-qubit quantum characteristics. We show that a harmonic reservoir controlled by Ohmic noise prevails a monotonic-like decay in the current case where, sooner or later, the state becomes completely disentangled, decoherent, and mixed. The QMA-EU has always been found to have an increasing function causing the quantum resourcefulness to be reduced. Although, there is no pathway to avoid the Ohmic noise consequences and complete decay, however, we provided parameterization which would lead to prolonged preservation of quantum correlations with time. Finally, we provide various settings for the tuning of cut-off frequency regarding the Ohmic type bath and state parameters on the initial as well as final levels of quantum features.

Digital quantum simulation of non-perturbative dynamics of open systems with orthogonal polynomials

Classical non-perturbative simulations of open quantum systems' dynamics face several scalability problems, namely, exponential scaling of the computational effort as a function of either the time length of the simulation or the size of the open system. In this work, we propose the use of the Time Evolving Density operator with Orthogonal Polynomials Algorithm (TEDOPA) on a quantum computer, which we term as Quantum TEDOPA (Q-TEDOPA), to simulate non-perturbative dynamics of open quantum systems linearly coupled to a bosonic environment (continuous phonon bath). By performing a change of basis of the Hamiltonian, the TEDOPA yields a chain of harmonic oscillators with only local nearest-neighbour interactions, making this algorithm suitable for implementation on quantum devices with limited qubit connectivity such as superconducting quantum processors. We analyse in detail the implementation of the TEDOPA on a quantum device and show that exponential scalings of computational resources can potentially be avoided for time-evolution simulations of the systems considered in this work. We applied the proposed method to the simulation of the exciton transport between two light-harvesting molecules in the regime of moderate coupling strength to a non-Markovian harmonic oscillator environment on an IBMQ device. Applications of the Q-TEDOPA span problems which can not be solved by perturbation techniques belonging to different areas, such as the dynamics of quantum biological systems and strongly correlated condensed matter systems.

Sublinear Scaling in Non-Markovian Open Quantum Systems Simulations

While several numerical techniques are available for predicting the dynamics of non-Markovian open quantum systems, most struggle with simulations for very long memory and propagation times, e.g., due to superlinear scaling with the number of time steps n. Here, we introduce a numerically exact algorithm to calculate process tensors—compact representations of environmental influences—which provides a scaling advantage over previous algorithms by leveraging self-similarity of the tensor networks that represent the environment. It is applicable to environments with Gaussian statistics, such as for spin-boson-type open quantum systems. Based on a divide-and-conquer strategy, our approach requires only O(n log n) singular value decompositions for environments with infinite memory. Where the memory can be truncated after nc time steps, a nominal scaling O(nc log nc) is found, which is independent of n. This improved scaling is enabled by identifying process tensors with repeatable blocks. To demonstrate the power and utility of our approach, we provide three examples. (1) We calculate the fluorescence spectra of a quantum dot under both strong driving and strong dot-phonon couplings, a task requiring simulations over millions of time steps, which we are able to perform in minutes. (2) We efficiently find process tensors describing superradiance of multiple emitters. (3) We explore the limits of our algorithm by considering coherence decay with a very strongly coupled environment. The observed computation time is not necessarily proportional to the number of singular value decompositions because the matrix dimensions also depend on the number of time steps. Nevertheless, quasilinear and sublinear scaling of computation time is found in practice for a wide range of parameters. While there are instances where existing methods can achieve comparable nominal scaling by precalculating effective propagators for time-independent or periodic system Hamiltonians, process tensors contain all the information needed to extract arbitrary multitime correlation functions of the system when driven by arbitrary time-dependent system Hamiltonians. The algorithm we present here not only significantly extends the scope of numerically exact techniques to open quantum systems with long memory times, but it also has fundamental implications for the simulation complexity of tensor network approaches. Published by the American Physical Society 2024

Path integral quantum algorithm for simulating non-Markovian quantum dynamics in open quantum systems

Research in open quantum system dynamics has received growing interest in recent years, and its ongoing investigation has uncovered many intriguing physics departing from closed systems. A particularly useful application of the open quantum system theory is to simulate quantum dynamical processes in condensed phase materials. As the quantum degree of freedom is constantly under the influence of its thermal environment, the accurate description of the dynamics often requires non-Markovian time evolution at finite temperature. Such calculation is usually quite challenging on classical computers as extensive memory storage is required. In this work, we focus on a quantum system linearly coupled to its harmonic bath and present a path integral based quantum algorithm that time-evolves the reduced density matrix under finite temperature non-Markovian dynamics. To treat the nonunitary time evolution, the Sz.-Nagy dilation scheme is used for the conversion to unitary dynamics that can be implementable on gate-based quantum computers. The modified Hadamard test is then used to retrieve all the information of the reduced density matrix. Complexity analysis shows that the memory requirement has exponential reduction on the quantum machine whereas the runtime complexity stays roughly the same as for the classical computer. It points to the possibility of using this algorithm to simulate multilevel and multisite non-Markovian quantum dynamics that are beyond the reach of classical computers. The algorithm makes no ad hoc assumptions and extends naturally beyond Markovian and weak coupling regimes. We validated the algorithm on the quantum simulator with the spin-boson model and demonstrated its excellent agreement with the classical computer benchmark. Published by the American Physical Society 2024

Efficient quantum simulation of open quantum system dynamics on noisy quantum computers

Quantum simulation represents the most promising quantum application to demonstrate quantum advantage on near-term noisy intermediate-scale quantum (NISQ) computers, yet available quantum simulation algorithms are prone to errors and thus difficult to realize with limited circuit depth on nowadays quantum devices. Herein, we propose a novel scheme to utilize intrinsic gate errors of NISQ devices to enable controllable simulation of open quantum system dynamics without ancillary qubits or explicit bath engineering, thus turning unwanted quantum noises into useful quantum resources. Specifically, we simulate the energy transfer process in a photosynthetic dimer system on IBM-Q cloud. By employing tailored decoherence-inducing gates, we show that quantum dissipative dynamics can be simulated efficiently across coherent-to-incoherent regimes with results comparable to those of the numerically exact classical method. Moreover, we demonstrate a calibration routine that enables consistent and predictive simulations of open-quantum system dynamics in the intermediate coupling regime. This work provides a new direction for quantum advantage in the NISQ era.

I like therefore I can, and I can therefore I like: the role of self-efficacy and affect in active inference of allostasis.

Active inference (AIF) is a theory of the behavior of information-processing open dynamic systems. It describes them as generative models (GM) generating inferences on the causes of sensory input they receive from their environment. Based on these inferences, GMs generate predictions about sensory input. The discrepancy between a prediction and the actual input results in prediction error. GMs then execute action policies predicted to minimize the prediction error. The free-energy principle provides a rationale for AIF by stipulating that information-processing open systems must constantly minimize their free energy (through suppressing the cumulative prediction error) to avoid decay. The theory of homeostasis and allostasis has a similar logic. Homeostatic set points are expectations of living organisms. Discrepancies between set points and actual states generate stress. For optimal functioning, organisms avoid stress by preserving homeostasis. Theories of AIF and homeostasis have recently converged, with AIF providing a formal account for homeo- and allostasis. In this paper, we present bacterial chemotaxis as molecular AIF, where mutual constraints by extero- and interoception play an essential role in controlling bacterial behavior supporting homeostasis. Extending this insight to the brain, we propose a conceptual model of the brain homeostatic GM, in which we suggest partition of the brain GM into cognitive and physiological homeostatic GMs. We outline their mutual regulation as well as their integration based on the free-energy principle. From this analysis, affect and self-efficacy emerge as the main regulators of the cognitive homeostatic GM. We suggest fatigue and depression as target neurocognitive phenomena for studying the neural mechanisms of such regulation.

Dissipative coupling induced UWB magnonic frequency comb generation

Magnonic frequency combs have recently attracted particular attention due to their potential impact on spin-wave science. Here, we demonstrate theoretically the generation of ultra-wideband magnonic frequency combs induced by dissipative coupling in an open cavity magnomechanical system. A broadband comb with gigahertz repetition rates is obtained in the magnonic spectrum, and a typical non-perturbation frequency-comb structure is also observed. The total width of the magnonic comb in the robust plateau region can be up to ∼400 comb lines, which is much broader and flatter than that reported in the previous works. Furthermore, when the dissipative coupling strength is further increased, the chaotic motion is predicted in the magnonic spectrum. Our results provide an in-depth understanding of nonlinear magnomechanic dynamics in open quantum systems and fundamentally broaden the research range of magnon in wider spectral regimes.

Quantum advantage of time-reversed ancilla-based metrology of absorption parameters

Quantum estimation of parameters defining open-system dynamics may be enhanced by using ancillas that are entangled with the probe but are not submitted to the dynamics. Here we consider the important problem of estimation of transmission of light by a sample, with losses due to absorption and scattering. We show, through the determination of the quantum Fisher information, that the ancilla strategy leads to the best possible precision in single-mode estimation—the one obtained for a Fock-state input—through joint photon counting of probe and ancilla, which are modes of a bimodal squeezed state produced by an optical parametric amplifier. This proposal overcomes the challenge of producing and detecting high-photon-number Fock states, and it is quite robust in the presence of additional noise: We show that it is immune to phase noise and the precision does not change if the incoming state gets disentangled. Furthermore, the quantum gain is still present under moderate photon losses of the input beams. We also discuss an alternative to joint photon counting, which is readily implementable with present technology and approaches the quantum Fisher information result for weak absorption, even with moderate photon losses of the input beams before the sample is probed: a time-reversal procedure, placing the sample between two optical parametric amplifiers, with the second undoing the squeezing produced by the first one. The precision of estimation of the loss parameter is obtained from the average outgoing total photon number and its variance. In both procedures, the state of the probe and the detection procedure are independent of the value of the parameter. Published by the American Physical Society 2024

THE LEXEME "HARMONY" IN ENGLISH: DICTIONARY DEFINITIONS’ ANALYSIS

The article is devoted to the semantic structure of the concept of "harmony" in English by analysing dictionary definitions based on 12 monolingual dictionaries, aiming to define the nominative lexeme “harmony”. The research resulted in distinguishing the core seme, median part and periphery of the concept, their dominance or peripherality of the semes being analysed according to the frequency of their appearance in the dictionaries. The etymology of the concept of “harmony” is also outlined in the article starting with the Greek word “harmonia” (where it is believed to be a derivative from an Indo-European verb root -ar-), the first appearance of the concept in the Middle English and to its usage in the modern language. Consequently, the development of this concept as an open dynamic system is demonstrated according to the process of its evolution from the core seme having totally physical meaning to the peripheral ones, the meanings of which are rather metaphorical. Besides, the impact of outside circumstances is considered one of the reasons for the fact that not all the features of this concept are fully verbalised in the language. As follows, the conclusion is made about the permanent development of the concept as a system. This corresponds to the general theory of a concept’s development which extends from the sensory-visual image that constitutes the core of the concept, through the gradual layering of "basic layers, where the features are arranged in progressively more abstract ways.

PUBLIC ADMINISTRATION OF SUSTAINABLE DEVELOPMENT OF RURAL TERRITORIES

Background . This article is focused on specifics of sustainable development of rural territories as a milestone on the way to harmonious regional development. Notably, dynamics and realities of rural territories challenge sustainable development and require some ways to maintain it. There is evident asymmetry between sustainable development of rural and urban territories, and the government has to take measures to ensure equal access to resources and opportunities for those territories to unleash their potential. Methods . In the preparation of the research, both general methods, including methods of abstraction, logic, synthesis and analysis (in particular, causal analysis), extrapolation, and special methods and approaches were used. Thus, a chronological (historical) approach is used when analyzing trends in the development of rural areas compared to urban areas; a complex of methods belonging to a wide range of systems theory (when analyzing correlations between environments of different levels, connections, resources, dynamic open systems, analysis of homeostats of the specified systems); activity approach – when characterizing the reasons for the mobility of the rural and urban population; modeling – when making forecasts of the development of territories. Results . The social aspect of sustainable development of rural territories endeavors to strengthen the ties between public authorities and community stakeholders in order to find the integral solutions consistent with dynamics of the relevant regions and capable of taking the challenges. The environmental aspect outlines the land use conflict arising out of the economic activities in the relevant areas of interest. The economic aspect has to be seek economic equality and equal access to jobs for rural and urban population, as well as improve the quality of life for the villagers. Conclusions . The article identifies the new factors that have to be studied in the development models, for example, the ever-growing ties between city and village life, the economic activity changes emerging in the rural areas due to transfer from the traditional agriculture to secondary production and services. It has been proven that village and city relationship is a deciding factor governing sustainable regional development, because spatial differences between cities and suburban areas are growing, and therefore it is necessary to study regional development to analyze interlinkage between rural and urban territories

Metastable dynamics of Rydberg atomic system under electromagnetically induced transparency

Open quantum system, coupled with an external bath is a key research field of quantum physics. Steady state is the state in which any initial state converges after a long time and is usually of the most interest. However, relatively speaking, the nonequilibrium dynamical processes of quantum many-body systems have been rarely studied. This is mainly due to the fact that quantum many-body systems generally have interactions, and the Hilbert space required for a complete description of their dynamical processes will grow exponentially with the number of particles increasing, and the computational difficulty will increase dramatically as well. Hence, it is a difficult problem to completely describe their dynamical processes completely. With the development of quantum technologies, the interest in the nonequilibrium dynamics of open quantum many-body systems is aroused. A common phenomenon is the metastable state, where the system initially relaxes into a long-lived state and then converges to the final stationary state for a longer time. In this paper, we establish a low-dimensional approximation to describe the metastability dynamics in Markovian open quantum system, based on the spectra of the Liouvillian super-operator. The separation of time scales implies a splitting in the spectrum, and this spectral division allows us to eliminate the fast decay modes by using the perturbation method, and then we establish the effective description in the low-lying eigenmodes subspace. Furthermore, we study the dynamics process of the Rydberg atomic system under electromagnetically induced transparency (EIT) conditions and find that the system can handle metastable dynamics if the atomic interactions are considered. We compare the effective dynamics in the subspace with the actual dynamics in the full space, and the results show that the effective dynamics works well on condition that the perturbation approximation holds. Our work provides a feasible idea and method for establishing an effective and simplified description of the dynamical process of open quantum many-body systems.

Dynamics of spin relaxation in nonequilibrium magnetic nanojunctions

We investigate nonequilibrium phenomena in magnetic nano-junctions using a numerical approach that combines classical spin dynamics with the hierarchical equations of motion technique for quantum dynamics of conduction electrons. Our focus lies on the spin dynamics, where we observe non-monotonic behavior in the spin relaxation rates as a function of the coupling strength between the localized spin and conduction electrons. Notably, we identify a distinct maximum at intermediate coupling strength, which we attribute to a competition that involves the increasing influence of the coupling between the classical spin and electrons, as well as the influence of decreasing local density of states at the Fermi level. Furthermore, we demonstrate that the spin dynamics of a large open system can be accurately simulated by a short chain coupled to semi-infinite metallic leads. In the case of a magnetic junction subjected to an external DC voltage, we observe resonant features in the spin relaxation, reflecting the electronic spectrum of the system. The precession of classical spin gives rise to additional side energies in the electronic spectrum, which in turn leads to a broadened range of enhanced damping in the voltage.

Spin-Vibronic Dynamics in Open-Shell Systems beyond the Spin Hamiltonian Formalism.

Vibronic coupling has a dramatic influence over a large number of molecular processes, ranging from photochemistry to spin relaxation and electronic transport. The simulation of vibronic coupling with multireference wave function methods has been largely applied to organic compounds, and only early efforts are available for open-shell systems such as transition metal and lanthanide complexes. In this work, we derive a numerical strategy to differentiate the molecular electronic Hamiltonian in the context of multireference ab initio methods and inclusive of spin-orbit coupling effects. We then provide a formulation of open quantum system dynamics able to predict the time evolution of the electron density matrix under the influence of a Markovian phonon bath up to fourth-order perturbation theory. We apply our method to Co(II) and Dy(III) molecular complexes exhibiting long spin relaxation times and successfully validate our strategy against the use of an effective spin Hamiltonian. Our study sheds light on the nature of vibronic coupling, the importance of electronic excited states in spin relaxation, and the need for high-level computational chemistry to quantify it.

Quantum algorithm for solving open-system dynamics on quantum computers using noise

Quantum algorithm for solving open-system dynamics on quantum computers using noise

Long-Term Behaviour in an Exactly Solvable Model of Pure Decoherence and the Problem of Markovian Embedding

We consider a well-known, exactly solvable model of an open quantum system with pure decoherence. The aim of this paper is twofold. Firstly, decoherence is a property of open quantum systems important for both quantum technologies and the fundamental question of the quantum–classical transition. It is worth studying how the long-term rate of decoherence depends on the spectral density characterising the system–bath interaction in this exactly solvable model. Secondly, we address a more general problem of the Markovian embedding of non-Markovian open system dynamics. It is often assumed that a non-Markovian open quantum system can be embedded into a larger Markovian system. However, we show that such embedding is possible only for Ohmic spectral densities (for the case of a positive bath temperature) and is impossible for both sub- and super-Ohmic spectral densities. On the other hand, for Ohmic spectral densities, an asymptotic large-time Markovianity (in terms of the quantum regression formula) takes place.

SUSTAINABLE ARCHITECTURE – CONTRADICTIONS AND CONFLICTS

The problems of sustainable architecture are considered through the prism of creating architectural buildings and urban environments that provide environmental, economic and socio-cultural sustainability. In order to understand the complexity and nature of the permanence of architecture, it should be considered as a fragment of the overall open dynamic system of the city. At the same time, all components of such a system are interconnected by the general dynamics of functioning and often develop in conditions of internal systemic contradictions. The intra-system contradictions of the city as an open dynamic system should be understood as a situation where the attempts of any element of the system to achieve the conditions of optimal functioning are limited or suppressed by other elements of the system. Architecture, as an artificial environment in which these systemic contradictions arise, is forced to respond flexibly to them. The purpose of this work is to identify the systemic contradictions that arise in the process of functioning of the architectural component of the city as an open dynamic system, and to generalize these contradictions. 
 In the development of any system, stability and instability, adaptation and maladaptation are equally necessary. An absolutely unstable system is devoid of the ability to adapt and quickly collapses, while an ultra-stable system, suppressing any fluctuations, retains its structure and behavior, is not able to change qualitatively, that is, it is deprived of the possibility of development, and its destruction becomes only a matter of time. Both types of systems descend into chaos, the difference between them being the time it takes for entropy to explode. 
 The change in the evolutionary and revolutionary stages of the development of systems, their stability and instability forms dynamic cycles in time. Each system has not only cyclical processes due to its nature, but also cycles dictated by the environment. Moreover, the "external" cycles are more stable and stable, while the cycles of internal origin can change under their influence as a result of synchronization - the properties of systems of a diverse nature to produce a single rhythm of coexistence, despite the sometimes extremely weak interconnection.

“Text of Culture” as a Category of Cultural Philosophy: from Semiotic Theory to Research Practice

Introduction. Culture manifests itself in texts, one “reads” them, communicates with them. This communication takes place with varying degrees of competence; a high degree of competence is a necessary requirement for “reading” a cultural text in research practice. The article presents a metatheoretical construction on the basis of the analysis of the semiotic theory of the “text of culture” of the Tartu-Moscow school. The aim of the analysis is to develop a cultural-philosophical research practice. The author addresses the following tasks: justification of the necessity of metatheoretical constructions around Lotman's semiotics of culture; categorisation of the “text of culture”; characterisation of the semiosis of the “text of culture” as the necessary generation of the metatext; outlining the principles of research "reading" of the “text of culture”. The article is of a theoretical and methodological character.Methodology and sources. The methodological basis of the research is the traditions of Russian cultural semiotics and the Tartu-Moscow semiotic school. The main parameters for the selection of scientific publications: the degree of semiotic problematization of the cultural text; the possibility of explicating the concepts being sought; the perspective of meta-theoretical constructions.Results and discussion. The study allows us to formulate theoretical and methodological conclusions. The necessity of developing semiotics of culture in the Tartu-Moscow school is justified by the increasing complexity of modern culture as an open dynamic system, and by the un-realized methodological purpose of the institution. The “text of culture” is the most important notion of cultural-philosophical research. Its necessary categorization opens perspectives for the development of procedures of semiotic analysis of artifact as the “text of culture”, and for the interpretation of its semiosis, taking into account the mechanisms of functioning of immanent structures. The most important direction of cultural-philosophical analysis of the cultural text is its semiosis, which is treated as the sign functioning of the artifact-text within the boundaries of an open system that is culture as “one”.Conclusion. Principle aspects of the proposed cultural-philosophical practice: 1) the categorical system of semiotics of culture has to include the position of “text of culture” which fixes genetic relationship of text and culture; 2) “semiosis” of artifact as “text of culture” naturally generates metatextual space of culture as a result of systems openness within the borders of culture as “the one”.

Медийная картина мира как объект научного описания

The purpose of the article is to consider the formation, development and modern approaches to the study of one of the key concepts for media research — the media picture of the world. The relevance of the study is due to the growing influence of media representation of events formed by the media with the help of linguomedia construction technologies on public consciousness and behavior. The study of the media picture of the world as an object of scientific description is based on an integrative approach,
 including its consideration in a historical perspective, analysis of various approaches to definition, as well as a review of modern theories and methods of study. Particular attention is paid to the historical and philosophical roots of the modern interpretation of the concept of “media picture of the world”, domestic research in this area, as well as methods of modeling the modern media picture of the world, which allows us to analyze the processes of formation of media images in dynamics. As a result of the study, the key properties of the media picture of the world are highlighted, such as:the media picture of the world is an open nonlinear dynamic system that has both a holistic and mosaic character; The media picture of the world,formed by national media, reflects and reproduces the sociocultural specifics of a certain civilizational community and region.