Machine learning methods have proved to be useful for the recognition of patterns in statistical data. The measurement outcomes are intrinsically random in quantum physics, however, they do have a ...pattern when the measurements are performed successively on an open quantum system. This pattern is due to the system-environment interaction and contains information about the relaxation rates as well as non-Markovian memory effects. Here we develop a method to extract the information about the unknown environment from a series of projective single-shot measurements on the system (without resorting to the process tomography). The method is based on embedding the non-Markovian system dynamics into a Markovian dynamics of the system and the effective reservoir of finite dimension. The generator of Markovian embedding is learned by the maximum likelihood estimation. We verify the method by comparing its prediction with an exactly solvable non-Markovian dynamics. The developed algorithm to learn unknown quantum environments enables one to efficiently control and manipulate quantum systems.
The difficulty to simulate the dynamics of open quantum systems resides in their coupling to many-body reservoirs with exponentially large Hilbert space. Applying a tensor network approach in the ...time domain, we demonstrate that effective small reservoirs can be defined and used for modeling open quantum dynamics. The key element of our technique is the timeline reservoir network (TRN), which contains all the information on the reservoir's characteristics, in particular, the memory effects timescale. The TRN has a one-dimensional tensor network structure, which can be effectively approximated in full analogy with the matrix product approximation of spin-chain states. We derive the sufficient bond dimension in the approximated TRN with a reduced set of physical parameters: coupling strength, reservoir correlation time, minimal timescale, and the system's number of degrees of freedom interacting with the environment. The bond dimension can be viewed as a measure of the open dynamics complexity. Simulation is based on the semigroup dynamics of the system and effective reservoir of finite dimension. We provide an illustrative example showing the scope for new numerical and machine learning-based methods for open quantum systems.
The flow around an elongated smooth contour under the free surface of a fluid is considered. The fluid is perfect, incompressible, and heavy. The critical flow branching and flow shedding points are ...located on the contour. The depth of the contour immersion and its length are given. It is assumed that the velocity magnitude on the free surface is close to its value in the undisturbed flow. A nonlinear approximation of the Bernoulli integral on the free surface associated with logarithm is used. Two auxiliary planes in which the flow domain is a half-plane with an excluded circle and an annular region are used. The complex potential is determined in the first parametric plane using a conformal mapping onto the annular region. A system of equations is derived for finding the defining parameters. This system is solved using the minimization of a functional and an iteration method over two sets of parameters. An algorithm and computer program for solving this system are developed. The hydrodynamic characteristics of a specific hydrofoil are computed. Results for the coefficients of wave drag, lift force, moment, and position of the contour center are analyzed depending on the Froude number and circulation of different signs. Examples of computations of nonlinear waves formed on the free surface at significant Froude numbers are given.
Climate policy is gradually becoming dominant in the world and is beginning to decisively determine the long-term prospects for the development of the global economy and energy. The problem of ...curbing the rise in global temperature is global; therefore, reducing greenhouse gas emissions as a result of anthropogenic activities must be carried out in the most acceptable way for the global economy and energy sector. The optimal paths for countries around the world to transition to a carbon-neutral economy will vary significantly since they have different economic structures and endowments of energy resources. The article discusses the following technological directions of decarbonization of the economy: intensification of energy conservation, including production, transformation, transportation, and consumption of energy; changing the fuel structure in favor of low-carbon fuels by replacing coal with natural gas; replacing fossil fuels with carbon-neutral biomass; CO
2
capture in energy and industrial installations with its subsequent transportation and disposal; expanding the use of nuclear energy; and transition to the use of carbon-free renewable energy resources. For each of these areas, the potential for their contribution to achieving carbon neutrality in the economy and the existing restrictions on their implementation are identified. The research was carried out in relation to the economy and energy sector of Russia, which is one of the largest consumers and exporters of fossil organic fuels in the world. It is shown that the transition to a carbon-neutral economy must be complex and carried out through a combination of various technological solutions. The implementation of the “electric world” concept in the country, in which all basic energy needs will be met by using electricity produced on a carbon-free basis, until 2060 is hardly possible for technological and economic reasons, so the use of fossil organic fuels during this period will remain inevitable. At the same time, the issue of organizing the capture and disposal of CO
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must be resolved.
The deployment of CO
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capture and storage (or carbon capture and storage (CCS)) technologies will enable carbon neutrality to be achieved during commercial utilization of fossil fuels. The performed ...studies have demonstrated that CCS technologies are quite energy-intensive and expensive. This primarily concerns the CO
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capturing equipment, which is responsible for 60–80% of the CCS total expenditures. With a decrease in the partial pressure of CO
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in a gas mixture and the capacity of the capture plant, the cost of CO
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extraction increases drastically. This applies particularly to thermal power plants (TPPs). Their provision with CO
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capture systems increases the specific capital expenditures by 1.6–2.3 times and the cost of generated electricity by 1.4–1.6 times. The power required for operation of these system amounts to approximately 9–12% of the total plant output and up to 20% with certain technologies. The unit cost of CO
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capture becomes much greater if the power plant capacity is below 200 MW. The deployment of the CCS industry will require construction of a branched pipeline system for transportation of large volumes of CO
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, comparable to the gas transmission system. This will extend the potential for application of CCS technologies. The specific expenditures for pipeline transportation of CO
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are controlled by the transported amount and phase state of CO
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. Increasing the transported amount of CO
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from 0.1 to 5.0 million t/year cuts down the unit cost of transportation by almost an order of magnitude. The expenditures for CO
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storage depends essentially on the characteristics of the geological reservoir. The cheapest option of CO
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storage is onshore depleted oil and gas fields. Development of the CCS technology basis requires generous state support.
—We present the results of studying the depths to lithospheric magnetic sources under the East Siberian Sea. The azimuthally-averaged Fourier power spectra of geomagnetic anomalies have been ...calculated from the global model EMAG2v3, which is the most current compilation of marine, aeromagnetic, ground, and satellite geomagnetic surveys. The depths to the centroid, the upper and lower boundaries of the magnetoactive layer have been calculated from the obtained spectra by the centroid method. The analysis of the results included comparing the depth distributions with known data on the thicknesses of sediments and the Earth’s crust, the depths of regional earthquake hypocenters, the surface heat flow, and the tectonic structure of the study region. It has been concluded that the depth to the upper boundary of the magnetoactive layer varies from about 0.4 km under the De Long High to 7 km under the New Siberian and East Siberian sedimentary basins. The depth to the lower boundary of the lithospheric magnetic sources varies from about 25 km under the De Long massif and the Podvodnikov Basin to 43 km under the New Siberian-Chukchi fold belt. In the considered territory, the lithospheric magnetoactive layer is located entirely within the Earth’s crust under the continent, the New Siberian Islands, the De Long High, and the western section of the East Siberian Sea shelf. The upper mantle is magnetic under the eastern section of the shelf and the Podvodnikov Basin. The obtained results indicate stronger warming of the lithosphere in the north of the study territory: under the Podvodnikov Basin and the De Long massif, characterized by suboceanic and continental crustal types, respectively.
Three‐dimensional (3D) terrain modeling based on digital elevation models (DEMs) with the use of orthographic and perspective projections is a standard procedure implemented in many commercial and ...open‐source geoinformation systems. However, standard tools may be insufficient for 3D scientific visualization. In particular, single‐source illumination of 3D models may be deficient for topographically complex terrains. We present an approach for 3D terrain modeling with multiple‐source illumination in the virtual environment of the Blender free and open‐source software. The approach includes the following key stages: (1) automatic creation of a polygonal object; (2) selecting an algorithm to model the 3D geometry; (3) selecting a vertical exaggeration scale; (4) selecting types, parameters, a number, and positions of light sources; (5) selecting methods for generating shadows; (6) selecting a shading method for the 3D model; (7) selecting a material for the 3D model surface; (8) overlaying a texture on the 3D model; (9) setting a virtual camera; and (10) rendering the 3D model. To illustrate the approach, we processed a test DEM extracted from the International Bathymetric Chart of the Arctic Ocean version 3.0 (IBCAO 3.0). The approach is currently being used to develop a system for geomorphometric modeling of the Arctic Ocean floor.
The buckling of a thin cylindrical shell supported by identical annular plates under uniform external pressure is analyzed using an asymptotic method. The boundary conditions on an internal parallel ...of the shell joined to a thin plate are obtained. The free support conditions are introduced at the edges of the shell. The approximate solutions to the eigenvalue problem are sought as a sum of slowly varying functions and edge effect integrals. For the formulation of the zero-order eigenvalue problem, the main boundary conditions are obtained on the parallel of the interface between the plate and the shell. This problem also describes vibrations of a simply supported beam stiffened by springs. Its solution is sought as linear combinations of Krylov’s functions. It is shown that in the zeroth approximation it is possible to replace a narrow plate with a circular beam. As the plate width increases, the stiffness of the corresponding spring tends to a constant. It occurs because of localized plate deformations in the proximity of the internal edge of the plate. As an example, the dimensionless critical pressure is determined in the case when the shell is supported by a single plate. Replacing a narrow plate with a circular beam does not lead to substantial variation in the critical pressure; however, for a wide plate the beam model provides an overestimated value of the critical pressure.
Absolutely separable states remain separable under arbitrary unitary transformations U U † . By example of a three qubit system we show that in a multipartite scenario neither full separability ...implies bipartite absolute separability nor the reverse statement holds. The main goal of the paper is to analyze quantum maps resulting in absolutely separable output states. Such absolutely separating maps affect the states in a way, when no Hamiltonian dynamics can make them entangled afterwards. We study the general properties of absolutely separating maps and channels with respect to bipartitions and multipartitions and show that absolutely separating maps are not necessarily entanglement breaking. We examine the stability of absolutely separating maps under a tensor product and show that Φ N is absolutely separating for any N if and only if Φ is the tracing map. Particular results are obtained for families of local unital multiqubit channels, global generalized Pauli channels, and combination of identity, transposition, and tracing maps acting on states of arbitrary dimension. We also study the interplay between local and global noise components in absolutely separating bipartite depolarizing maps and discuss the input states with high resistance to absolute separability.
We review quantum mappings used in problems of characterization of entanglement of two-part and multi-particle systems. Together with positive and
n
-tensorial constant positive mappings, we consider ...physical dynamical processes that lead to quantum channels that break entanglement, annihilate entanglement, dissociate entanglement of multi-particle states, and prohibit distillation of output states. We introduce a new class of absolutely disentangling channels that provide absolutely separable states at the output, and also characterize a new class of entanglement-imposing channels whose output states are entangled. We present states that are most resistant to loss of entanglement and prove that they may differ from maximally entangled states.
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