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Biased dynamics of the miscible-immiscible quantum phase transition in a binary Bose-Einstein condensate

Physical Review B 2024年第6期109卷 064501-064501页

作者： Francis A. Bayocboc, Jr. Jacek Dziarmaga Wojciech H. Zurek Jagiellonian University Faculty of Physics Astronomy and Applied Computer Science Institute of Theoretical Physics ul. Łojasiewicza 11 30-348 Kraków Poland Jagiellonian University Mark Kac Center for Complex Systems Research ul. Łojasiewicza 11 30-348 Kraków Poland Theoretical Division Los Alamos National Laboratory Los Alamos New Mexico 87545 USA

A quantum phase transition from the miscible to the immiscible phase of a quasi-one-dimensional binary Bose-Einstein condensate is driven by ramping down the coupling amplitude of its two hyperfine states. It results in a random pattern of spatial domains where the symmetry is broken separated by defects. In distinction to previous studies [J. Sabbatini et al., Phys. Rev. Lett. 107, 230402 (2011), New J. Phys. 14, 095030 (2012)], we include nonzero detuning between the light field and the energy difference of the states, which provides a bias towards one of the states. Using the truncated Wigner method, we test the biased version of the quantum Kibble-Zurek mechanism [M. Rams et al., Phys. Rev. Lett. 123, 130603 (2019)] and observe a crossover to the adiabatic regime when the quench is sufficiently fast to dominate the effect of the bias. We verify a universal power law for the population imbalance in the nonadiabatic regime both at the critical point and by the end of the ramp. Shrinking and annihilation of domains of the unfavorable phase after the ramp, that is, already in the broken symmetry phase, enlarges the defect-free sections by the end of the ramp. The consequences of this phase-ordering effect can be captured by a phenomenological power law.

关键词： Quantum phase transitions Bose-Einstein condensates Stochastic dynamical systems Ultracold gases

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Sources of optical radiation based on ZnTe/ZnSe/ZnS heterostructures

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Materials Today: Proceedings 2022年 62卷 5763-5766页

作者： Slyotov, Mykhailo Mazur, Tetiana Prokopiv, Volodymyr Slyotov, Oleksii Mazur, Myroslav Department of Optics Physical Publishing and Printing/Technical and Computer Science Institute Yuriy Fedkovych Chernivtsi National University 2 Kotsubinsky Str. Chernivtsi 58012 Ukraine Department of General and Applied Physics/Institute of Architecture Construction and Power Engineering Ivano-Frankisvsk National Technical University of Oil and Gas 15 Karpatska Str. Ivano-Frankivsk 76019 Ukraine Department of Solid State Physics and Chemistry/Faculty of Physics and Technology Vasyl Stefanyk Precarpathian National University 57 Shevchenko Str. Ivano-Frankivsk 76019 Ukraine

The heterostructures of zinc chalcogenides β-ZnTe/ZnSe/ZnS were obtained by isovalent substitution. The regimes for obtaining materials that ensured the stability of the cubic lattice of heterolayers of zinc chalcogenides β-ZnSe and β-ZnS were determined. The isovalent elements Se and S determined the solid-phase substitution and determined the formation of heterolayers in the lattice of the surface of the base crystal. The optical transmission, reflection, and photoluminescence spectra of the heterolayers are studied. The analysis of the results of studies of the energy structure of the obtained heterolayers was carried out, which indicates the correspondence of these heterolayers to the compounds of zinc selenide and zinc sulfide obtained by classical technological processes. They are also confirmed by the results of studies of the optical transmission of β-ZnSe and β-ZnS films specially obtained on transparent substrates under the same growing conditions as compared to isovalent substitution. © 2022

关键词： Light transmission

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PyPartMC: A Pythonic Interface to a Particle-Resolved, Monte Carlo Aerosol Simulation Framework

SSRN

引用

SSRN 2023年

作者： D’Aquino, Zachary Arabas, Sylwester Curtis, Jeffrey H. Vaishnav, Akshunna Riemer, Nicole West, Matthew Atmospheric Sciences University of Illinois Urbana-Champaign UrbanaIL United States Physics and Applied Computer Science AGH Univeristy of Krakow Kraków Poland Electrical and Computer Engineering University of Illinois Urbana-Champaign UrbanaIL United States Mechanical Science and Engineering University of Illinois Urbana-Champaign UrbanaIL United States

PyPartMC is a Pythonic interface to PartMC, a stochastic, particle-resolved aerosol model implemented in Fortran. Both PyPartMC and PartMC are free, libre, and open-source. PyPartMC reduces the number of steps and mitigates the effort necessary to install and utilize the resources of PartMC. Without PyPartMC, setting up PartMC requires: working with UNIX shell, providing Fortran and C libraries, and performing standard Fortran and C source code configuration, compilation and linking. This can be challenging for those less experienced with computational research or those intending to use PartMC in environments where provision of UNIX tools is less straightforward (e.g., on Windows). PyPartMC offers a single-step installation/upgrade process of PartMC and all dependencies through the pip Python package manager on Linux, macOS, and Windows. This allows streamlined access to the unmodified and versioned Fortran internals of the PartMC codebase from both Python and other interoperable environments (e.g., Julia through PyCall). Consequently, users of PyPartMC can setup, run, process and visualize output of PartMC simulations using a single general-purpose programming language. © 2023, The Authors. All rights reserved.

关键词： Monte Carlo methods

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Thermal recall: Memory-assisted Markovian thermal processes

arXiv

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arXiv 2023年

作者： Czartowski, Jakub de Oliveira Junior, A. Korzekwa, Kamil Doctoral School of Exact and Natural Sciences Jagiellonian University Kraków30-348 Poland Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków30-348 Poland

We develop a resource-theoretic framework that allows one to bridge the gap between two approaches to quantum thermodynamics based on Markovian thermal processes (which model memoryless dynamics) and thermal operations (which model arbitrarily non-Markovian dynamics). Our approach is built on the notion of memory-assisted Markovian thermal processes, where memoryless thermodynamic processes are promoted to non-Markovianity by explicitly modelling ancillary memory systems initialised in thermal equilibrium states. Within this setting, we propose a family of protocols composed of sequences of elementary two-level thermalisations that approximate all transitions between energy-incoherent states accessible via thermal operations. We prove that, as the size of the memory increases, these approximations become arbitrarily good for all transitions in the infinite temperature limit, and for a subset of transitions in the finite temperature regime. Furthermore, we present solid numerical evidence for the convergence of our protocol to any transition at finite temperatures. We also explain how our framework can be used to quantify the role played by memory effects in thermodynamic protocols such as work extraction. Finally, our results show that elementary control over two energy levels at a given time is sufficient to generate all energy-incoherent transitions accessible via thermal operations if one allows for ancillary thermal systems. © 2023, CC BY.

关键词： Temperature

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Competing charge density wave phases in YNiC2

arXiv

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arXiv 2024年

作者： Roman, Marta Di Cataldo, Simone Stöger, Berthold Reisinger, Lisa Morineau, Emilie Kolincio, Kamil K. Michor, Herwig Institute of Solid State Physics TU Wien Wiedner Hauptstrasse 8-10 WienA-1040 Austria Institute of Physics and Applied Computer Science Faculty of Applied Physics and Mathematics Gdansk University of Technology Narutowicza 11/12 Gdansk80-233 Poland Dipartimento di Fisica Sapienza University of Rome Piazzale Aldo Moro 5 Rome00185 Italy X-Ray Center TU Wien Getreidemarkt 9 WienA-1060 Austria Faculty of Applied Physics and Mathematics Gdansk University of Technology Narutowicza 11/12 Gdansk80-233 Poland

Charge density wave (CDW) orders in YNiC2 are studied by means of combinedexperimental and computational techniques. On the experimental side, singlecrystals grown by the floating-zone method were examined by means of X-raydiffraction, as well as transport and thermal techniques. Density functionaltheory (DFT) calculations founded on the experimentally determined parent andCDW-modified crystal structures provide details of electronic and phononicstructures as well as electron-phonon coupling and resolve changes inflictedupon entering the different CDW phases. Thereby, contrasting effects ofsubsequently emerging CDW states characterized by incommensurate q_{1ic} andcommensurate q_{2c} modulation vectors are revealed. The former state,on-setting below T_{1ic}~ 305 K, weakly modifies the electronic structure byopening an almost isotropic gap on a minor part of the Fermi surface (FS). Thelatter phase, which takes over below T_{2c}~ 272 K has a more pronounced impacton physical properties via a decomposition of larger parts of the FS. Thesedissimilar behaviors are directly reflected in the electronic transportanisotropy, which is significantly weakened in the q_{2c}-type CDW state. Asrevealed by our DFT studies, CDW phases are very close in energy and theirorigin is directly related to the anisotropy of electron-phonon coupling, whichis linked to a specific orbital character of related FS sheets. Specific heatand thermal expansion studies reveal a nearly reversible first-order phasetransition at around T_{2c}~ 272 K, where both CDW phases co-exist within aT-interval of about 10 K. Copyright © 2024, The Authors. All rights reserved.

关键词： Thermal expansion

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Contrastive Learning via Randomly Generated Deep Supervision

Contrastive Learning via Randomly Generated Deep Supervision

引用

International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Shibo Wang Zili Ma Ka-Hou Chan Yue Liu Tong Tong Qinquan Gao Guangtao Zhai Xiaohong Liu Tao Tan Faculty of Applied Sciences Macao Polytechnic University China Ischemaview Inc Menlo Park CA USA College of Physics and Information Engineering Fuzhou University Fuzhou China John Hopcroft Center for Computer Science Shanghai Jiao Tong University Shanghai China

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Unsupervised visual representation learning has gained significant attention in the computer vision community, driven by recent advancements in contrastive learning. Most existing contrastive learning frameworks rely on instance discrimination as a pretext task, treating each instance as a distinct category. However, this often leads to intra-class collision in a large latent space, compromising the quality of learned representations. To address this issue, we propose a novel contrastive learning method that utilizes randomly generated supervision signals. Our framework incorporates two projection heads: one handles conventional classification tasks, while the other employs a random algorithm to generate fixed-length vectors representing different classes. The second head executes a supervised contrastive learning task based on these vectors, effectively clustering instances of the same class and increasing the separation between different classes. Our method, Contrastive Learning via Randomly Generated Supervision(CLRGS), significantly improves the quality of feature representations across various datasets and achieves state-of-the-art performance in contrastive learning tasks.

关键词： Representation learning Visualization computer vision Signal processing algorithms Clustering algorithms Contrastive learning Signal processing Vectors Robustness Speech processing

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High thermoelectric power factor through topological flat bands

arXiv

引用

arXiv 2024年

作者： Garmroudi, Fabian Serhiienko, Illia Di Cataldo, Simone Parzer, Michael Riss, Alexander Grasser, Matthias Stockinger, Simon Khmelevskyi, Sergii Pryga, Kacper Wiendlocha, Bartlomiej Held, Karsten Mori, Takao Bauer, Ernst Pustogow, Andrej Institute of Solid State Physics TU Wien Vienna1040 Austria National Institute for Materials Science Tsukuba305-0044 Japan University of Tsukuba Tsukuba305-8577 Japan Dipartimento di Fisica Sapienza University of Rome Piazzale Aldo Moro 5 Roma00185 Italy Vienna Scientific Cluster Research Center TU Wien Vienna1040 Austria AGH University of Krakow Faculty of Physics and Applied Computer Science Aleja Mickiewicza 30 Krakow30-059 Poland

Thermoelectric (TE) materials are useful for applications such as waste heat harvesting or efficient and targeted cooling. While various strategies towards superior thermoelectrics through a reduction of the lattice thermal conductivity have been developed, a path to enhance the power factor is pressing. Here, we report large power factors up to 5 mW m−1 K−2 at room temperature in the kagome metal Ni3In1 – x Snx . This system is predicted to feature almost dispersionless flat bands in conjunction with highly dispersive Dirac-like bands in its electronic structure around the Fermi energy EF [L. Ye et al., Nature physics (2024)]. Within this study, we experimentally and theoretically showcase that tuning this flat band precisely below EF by chemical doping x boosts the Seebeck coefficient and power factor, as highly mobile charge carriers scatter into the flat-band states. Our work demonstrates the prospect of engineering extremely flat and highly dispersive bands towards the Fermi energy in kagome metals and introduces topological flat bands as a novel tuning knob for thermoelectrics. Copyright © 2024, The Authors. All rights reserved.

关键词： Fermi level

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Miniaturization of Dimensions Based on Square Loop Resonator with NP Fractal Model for Sensor Applications

Miniaturization of Dimensions Based on Square Loop Resonator...

引用

International Electrical Engineering Congress (iEECON)

作者： Nutyada Nantapanich Norakamon Wongsin Nipont Tangthong Chawalit Rakluea Paitoon Rakluea Wanchalerm Chanwattanapong Nonchanutt Chudpooti Chatree Mahatthanajatuphat Department of Electronics and Telecommunication Engineering Faculty of Engineering Rajamangala University of Technology Thanyaburi Thailand Department of Industrial Physics and Medical Instrumentation Faculty of Applied Science King Mongkut's University of Technology North Bangkok Bangkok Thailand Department of Electrical and Computer Engineering Faculty of Engineering King Mongkut's University of Technology North Bangkok Bangkok Thailand

ISBN: (数字)9798331543952

ISBN: (纸本)9798331543969

This paper proposes a reduction in the dimensions of a square loop resonator via the utilization of fractal techniques. The 2 nd order NP fractal model is investigated to minimize the dimensions of the square loop resonator. The suggested fractal resonator is indirectly fed via the coupling line encircling the resonator to enhance impedance matching. The suggested fractal resonator has a frequency response of 2.936 GHz, with |S11| and |S21| evaluated at -16.17 dB and -2.09 dB, respectively. The dimensions of the suggested fractal resonator are 10.5×10.5 mm 2 , representing a reduction of roughly 56.9% compared to the square loop resonator. Consequently, the suggested fractal resonator may serve as a sensor for the measuring instrument.

关键词： Electrical engineering Couplings Instruments Impedance matching Fractals Frequency response

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Non-Gaussian transverse momentum fluctuations from impact parameter fluctuations

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Physical Review C 2023年第2期108卷 024908-024908页

作者： Rupam Samanta João Paulo Picchetti Matthew Luzum Jean-Yves Ollitrault AGH University of Science and Technology Faculty of Physics and Applied Computer Science aleja Mickiewicza 30 30-059 Cracow Poland Université Paris Saclay CNRS CEA Institut de Physique Théorique 91191 Gif-sur-Yvette France Instituto de Física Universidade de São Paulo Rua do Matão 1371 Butantã 05508-090 São Paulo Brazil

The transverse momentum per particle, [pt], fluctuates event by event in ultrarelativistic nucleus-nucleus collisions, for a given multiplicity. These fluctuations are small and approximately Gaussian, but a nonzero skewness has been predicted on the basis of hydrodynamic calculations, and seen experimentally. We argue that the mechanism driving the skewness is that, if the system thermalizes, the mean transverse momentum increases with impact parameter for a fixed collision multiplicity. We postulate that fluctuations are Gaussian at fixed impact parameter, and that non-Gaussianities solely result from impact parameter fluctuations. Using recent data on the variance of [pt] fluctuations, we make quantitative predictions for their skewness and kurtosis as a function of the collision multiplicity. We predict, in particular, a spectacular increase of the skewness below the knee of the multiplicity distribution, followed by a fast decrease.

关键词： Particle correlations & fluctuations Relativistic heavy-ion collisions

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MONTE CARLO SIMULATION PLATFORM AND SOFTWARE STACK IN DOSE-3D PROJECT

Acta Physica Polonica B, Proceedings Supplement

引用

Acta Physica Polonica B, Proceedings Supplement 2022年第4期15卷

作者： Hajduga, Jakub Rachwal, Bartlomiej Szumlak, Tomasz Filipek, Marcin Fiutowski, Tomasz Górska, Wioleta Jurgielewicz, Pawel Kabat, Damian Kalecińska, Kamila Kaplon, Lukasz Kopeć, Maciej Koperny, Stefan Kulig, Dagmara Mindur, Bartosz Moroń, Jakub Moskal, Gabriel Ruciński, Antoni Wiącek, Piotr AGH University of Science and Technology Faculty of Physics and Applied Computer Science Mickiewicza 30 Kraków30-059 Poland Department of Medical Physics Maria Sklodowska-Curie National Research Institute of Oncology Kraków Branch Garncarska 11 Kraków31-115 Poland Cracow University of Technology Faculty of Materials Science and Physics Warszawska 24 Kraków31-155 Poland Department of Experimental Particle Physics and Applications Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków Lojasiewicza 11 Kraków30-348 Poland Total-Body Jagiellonian-PET Laboratory Jagiellonian University Lojasiewicza 11 Kraków30-348 Poland Department of Chemical Technology Faculty of Chemistry The Jagiellonian University Gronostajowa 2 Kraków30-387 Poland

The groundwork for the architecture and development of the software stack was described. The in-house MC simulation platform is being developed as well as Python-based utilities were described in detail. © 2022 J... 详细信息

关键词： Simulation platform

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