Experimental quantum homodyne tomography via machine learning

Complete characterization of states and processes that occur within quantum devices is crucial for understanding and testing their potential to outperform classical technologies for communications and computing. However, solving this task with current state-of-the-art techniques becomes unwieldy for large and complex quantum systems. Here we realize and experimentally demonstrate a method for complete characterization of a quantum harmonic oscillator based on an artificial neural network known as the restricted Boltzmann machine. We apply the method to optical homodyne tomography and show it to allow full estimation of quantum states based on a smaller amount of experimental data compared to state-of-the-art methods. We link this advantage to reduced overfitting. Although our experiment is in the optical domain, our method provides a way of exploring quantum resources in a broad class of large-scale physical systems, such as superconducting circuits, atomic and molecular ensembles, and optomechanical systems.Comment: 7+4 pages, 4+2 figure

Numerical modeling of a dilution and transport of highly salty effluent in water bodies

The paper focuses on modeling of dilution and transport of highly salty effluent in water bodies. The modeling is made for three-dimensional unsteady regimes of turbulent mixing in the conditions of strong density stratification. Numerical results allow to determine the limits of applicability of two-dimensional hydrodynamic models and to estimate the maximal possible environmentally safe volumes of highly salty effluent disposal

Annealing by simulating the coherent Ising machine

The coherent Ising machine (CIM) enables efficient sampling of low-lying energy states of the Ising Hamiltonian with all-to-all connectivity by encoding the spins in the amplitudes of pulsed modes in an optical parametric oscillator (OPO). The interaction between the pulses is realized by means of measurement-based optoelectronic feedforward which enhances the gain for lower-energy spin configurations. We present an efficient method of simulating the CIM on a classical computer that outperforms the CIM itself as well as the noisy mean-field annealer in terms of both the quality of the samples and the computational speed. It is furthermore advantageous with respect to the CIM in that it can handle Ising Hamiltonians with arbitrary real-valued node coupling strengths. These results illuminate the nature of the faster performance exhibited by the CIM and may give rise to a new class of quantum-inspired algorithms of classical annealing that can successfully compete with existing methods

The development and testing of a linear induction motor being fed from the source with a limited electric power

The report provides results of the research related to the single-phase linear induction motors (LIMs) for high voltage switch drives with the usage of inexpensive standard single-phase transformers for power supply. The LIMs’ design and investigations for other applications are described as well

Terrestrial crustaceans (Arthropoda, Crustacea): taxonomic diversity, terrestrial adaptations, and ecological functions

Terrestrial crustaceans are represented by approximately 4,900 species from six main lineages. The diversity of terrestrial taxa ranges from a few genera in Cladocera and Ostracoda to about a third of the known species in Isopoda. Crustaceans are among the smallest as well as the largest terrestrial arthropods. Tiny microcrustaceans (Branchiopoda, Ostracoda, Copepoda) are always associated with water films, while adult stages of macrocrustaceans (Isopoda, Amphipoda, Decapoda) spend most of their lives in terrestrial habitats, being independent of liquid water. Various adaptations in morphology, physiology, reproduction, and behavior allow them to thrive in virtually all geographic areas, including extremely arid habitats. The most derived terrestrial crustaceans have acquired highly developed visual and olfactory systems. The density of soil copepods is sometimes comparable to that of mites and springtails, while the total biomass of decapods on tropical islands can exceed that of mammals in tropical rainforests. During migrations, land crabs create record-breaking aggregations and biomass flows for terrestrial invertebrates. The ecological role of terrestrial microcrustaceans remains poorly studied, while omnivorous macrocrustaceans are important litter transformers and soil bioturbators, occasionally occupying the position of the top predators. Notably, crustaceans are the only group among terrestrial saprotrophic animals widely used by humans as food. Despite the great diversity and ecological impact, terrestrial crustaceans, except for woodlice, are often neglected by terrestrial ecologists. This review aims to narrow this gap discussing the diversity, abundance, adaptations to terrestrial lifestyle, trophic relationships and ecological functions, as well as the main methods used for sampling terrestrial crustaceans

Complete quantum-inspired framework for computational fluid dynamics

Computational fluid dynamics is both an active research field and a key tool for industrial applications. The central challenge is to simulate turbulent flows in complex geometries, a compute-power intensive task due to the large vector dimensions required by discretized meshes. Here, we propose a full-stack solver for incompressible fluids with memory and runtime scaling polylogarithmically in the mesh size. Our framework is based on matrix-product states, a powerful compressed representation of quantum states. It is complete in that it solves for flows around immersed objects of diverse geometries, with non-trivial boundary conditions, and can retrieve the solution directly from the compressed encoding, i.e. without ever passing through the expensive dense-vector representation. These developments provide a toolbox with potential for radically more efficient simulations of real-life fluid problems

The first fossil Petaurista (Mammalia: Sciuridae) from the Russian Far East and its paleogeographic significance

For the first time in the south of the Russian Far East in the Late Pleistocene cave deposits, fragments of the giant flying squirrel of the genus Petaurista were discovered. Petaurista tetyukhensis n. sp. is described based on a fragment of the upper jaw with two teeth and five isolated teeth from two cave locations. The main differences between the new species and living forms as well as other fossil species of the genus Petaurista are the absence of vertical groove on the lingual wall between the protocone and hypocone on M2, the absence of the anterior cross loph on the upper P4-M3, and the absence of mesoconids on lower, as a result of which the hypoflexid is not w-shaped. It is suggested that the Sikhote-Alin refugium allowed individual species to survive there during long unfavourable period of time and was the centre of speciation. © 2020Russian Foundation for Basic Research, RFBR: 18–04–00327National Science Foundation, NSF: 1417036This study was supported by the Russian Foundation for Basic Research (project 18–04–00327). Funding for radiocarbon dating of horse samples is provided by the NSF award № 1417036 to Dr. Beth Shapiro. We are thankful to Dr. Shapiro, Alisa Vershinina (UC Santa Cruz Paleogenomics Laboratory), John Southon and Chanda Bertrand (UC Irvine Keck CCAMS facility) for assistance with radiocarbon dating of these samples. We thank Prof. Hao-Wen Tong and an anonymous reviewer who offered constructive comments and helped to improve the manuscript considerably