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Quantum Dichotomies and Coherent Thermodynamics beyond First-Order Asymptotics

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PRX Quantum 2024年第2期5卷 020335-020335页

作者： Patryk Lipka-Bartosik Christopher T. Chubb Joseph M. Renes Marco Tomamichel Kamil Korzekwa Department of Applied Physics University of Geneva Geneva 1211 Switzerland Institute for Theoretical Physics ETH Zurich Zürich 8093 Switzerland Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Republic of Singapore Centre for Quantum Technologies National University of Singapore Singapore 117543 Republic of Singapore Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków 30-348 Poland

We address the problem of exact and approximate transformation of quantum dichotomies in the asymptotic regime, i.e., the existence of a quantum channel E mapping ρ1⊗n into ρ2⊗Rnn with an error ϵn (measured by trace distance) and σ1⊗n into σ2⊗Rnn exactly, for a large number n. We derive second-order asymptotic expressions for the optimal transformation rate Rn in the small-, moderate-, and large-deviation error regimes, as well as the zero-error regime, for an arbitrary pair (ρ1,σ1) of initial states and a commuting pair (ρ2,σ2) of final states. We also prove that for σ1 and σ2 given by thermal Gibbs states, the derived optimal transformation rates in the first three regimes can be attained by thermal operations. This allows us, for the first time, to study the second-order asymptotics of thermodynamic state interconversion with fully general initial states that may have coherence between different energy eigenspaces. Thus, we discuss the optimal performance of thermodynamic protocols with coherent inputs and describe three novel resonance phenomena allowing one to significantly reduce transformation errors induced by finite-size effects. What is more, our result on quantum dichotomies can also be used to obtain, up to second-order asymptotic terms, optimal conversion rates between pure bipartite entangled states under local operations and classical communication.

关键词： Information thermodynamics Mathematical physics Nonequilibrium & irreversible thermodynamics Quantum coherence & coherence measures Quantum information processing Quantum information theory Quantum thermodynamics Thermodynamics Statistical methods

Ambient- and high-pressure studies of structural, electronic, and magnetic properties of single-crystal EuZn2P2

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Physical Review B 2024年第1期110卷 014421-014421页

作者： Damian Rybicki Kamila Komędera Janusz Przewoźnik Łukasz Gondek Czesław Kapusta Karolina Podgórska Wojciech Tabiś Jan Żukrowski Lan Maria Tran Michał Babij Zbigniew Bukowski Ladislav Havela Volodymyr Buturlim Jiri Prchal Martin Divis Petr Kral Ilja Turek Itzhak Halevy Jiri Kastil Martin Misek Utpal Dutta Dominik Legut Faculty of Physics and Applied Computer Science al. A. Mickiewicza 30 30-059 Kraków Poland Mössbauer Spectroscopy Laboratory Faculty of Mathematics and Physics Department of Condensed Matter Physics Ke Karlovu 3 121 16 Prague 2 Czech Republic Unit of Nuclear Engineering Faculty of Engineering Science Na Slovance 1999/2 182 00 Prague 8 Czech Republic VŠB -

A thorough study of EuZn2P2 single crystals, which were grown from Sn flux, was performed using both bulk (heat capacity, ac susceptibility, dc magnetization, electrical resistivitivity, magnetoresistance) and microscopic (Mössbauer spectroscopy) techniques. Electrical resistance and magnetic susceptibility were measured also under high pressure conditions (up to 19 and 9.5 GPa, respectively). Further insight into electronic properties and phonons is provided by ab initio calculations. The results indicate that EuZn2P2 is an antiferromagnet with strong Eu-Eu exchange coupling of ferromagnetic type within the basal plane and weaker antiferromagnetic interaction along the c axis. The Eu magnetic moments are tilted from the basal plane. Hydrostatic pressure strongly affects both magnetic (increase of the Néel temperature) and electronic (suppression of the band gap and semimetallic behavior) properties, indicating a strong interplay of structure with magnetic and electronic degrees of freedom.

关键词： Antiferromagnetism Density of states Electronic structure of atoms & molecules First-principles calculations Antiferromagnets Rare-earth magnetic materials AC susceptibility measurements Crystal growth DC susceptibility measurements Magnetization measurements Mössbauer spectroscopy Pressure effects Pressure techniques Scanning electron microscopy Tight-binding model X-ray diffraction

Electric dipole spin resonance in single and two electron quantum dot defined in two-dimensional electron gas at the SrTiO3/LaAlO3 interface.

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arXiv 2023年

作者： Szafran, B. Zegrodnik, M. Nowak, M.P. Citro, R. Wójcik, P. AGH University of Krakow Faculty of Physics and Applied Computer Science Al. Mickiewicza 30 Krakow30-059 Poland AGH University of Krakow Academic Centre for Materials and Nanotechnology Al. Mickiewicza 30 Krakow30-059 Poland Fisciano132 Italy

We investigate the energy spectrum of a single and two electron quantum dot (QD) embedded in two dimensional electron gas at the interface between SrTiO3 and LaAlO3, in the presence of the external magnetic field. For this purpose the three band model of 3d-electrons defined on the square lattice of Ti ions was utilized. We demonstrate that, for the weak parabolic confinement potential, the low energy spectrum is sufficiently well described by the effective Hamiltonian reduced to the one dxy orbital with the spin-orbit interaction originating from the coupling to the dxz, dyz bands. This is not the case for stronger confinement where contribution of the states related to the dxz/yz orbital is relevant. Based on the time depended calculations we discuss in details the manipulation of the electron spin in QD by external AC voltages, in the context of the electric dipole spin resonance. The allowed and forbidden transitions are discussed in details with respect to the parity selection rule. Our calculations show that for a single electron QD the spin-flip in the ground-state has a character of a Rabi resonance while for two electrons the singlet-triplet transition is forbidden by the parity symmetry. For the two electrons QD, we demonstrate that the spin-flip transition can still be accomplished via a second-order, two-photon process that has a two-state Rabi character for low AC field amplitude. The violation of the parity symmetry on the spin-flip transitions is also analyzed. © 2023, CC BY.

关键词： Lanthanum compounds

Further evidence on the effect of magnetism on lattice vibrations: The case study of sigma-phase Fe0.525Cr0.455Ni0.020alloy

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arXiv 2022年

作者： Dubiel, Stanislaw M. Zukrowski, Jan Faculty Of Physics And Applied Computer Science AGH University Of Science And Technology KrakówPL-30-059 Poland Academic Center For Materials And Nanotechnology AGH University Of Science And Technology KrakówPL-30-059 Poland

Sigma-phase Fe0.525Cr0.455Ni0.020alloy was studied by means of Mössbauer spectrometry in the temperature range of 5-293 K. The average center shift, , determined from the recorded Mössbauer spectra was shown to significantly deviate from the Debye model in the temperature range below ∼50 K i.e. in the magnetic state of the sample. The deviation is obviously due to the effect of magnetism on the lattice dynamics of the studied sample. Analysis of the -data in the paramagnetic phase in terms of the Debye model yielded the value of 437(7) K for the Debye temperature. © 2022, CC BY-NC-ND.

关键词： Lattice vibrations

Electric field-based quantization of the gauge invariant Proca theory

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arXiv 2023年

作者： Damski, Bogdan Jagiellonian University Faculty of Physics Astronomy and Applied Computer Science Lojasiewicza 11 Kraków30-348 Poland

We consider the gauge invariant version of the Proca theory, where besides the real vector field there is also the real scalar field. We quantize the theory such that the commutator of the scalar field operator and the electric field operator is given by a predefined three-dimensional vector field, say E up to a global prefactor. This happens when the field operators of the gauge invariant Proca theory satisfy the proper gauge constraint. In particular, we show that E given by the classical Coulomb field leads to the Coulomb gauge constraint making the vector field operator divergenceless. We also show that physically unreadable gauge constraints can have a strikingly simple E-representation in our formalism. This leads to the discussion of Debye, Yukawa, etc. gauges. In general terms, we explore the mapping between classical vector fields and gauge constraints imposed on the operators of the studied theory. Copyright © 2023, The Authors. All rights reserved.

关键词： Vectors

Quantum correction to a new Wilson line-based action for Gluodynamics

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arXiv 2023年

作者： Kakkad, Hiren Kotko, Piotr Stasto, Anna Faculty of Physics and Applied Computer Science AGH University of Krakow al. A. Mickiewicza 30 Krakow30-059 Poland Physics Department The Pennsylvania State University 104 Davey Lab University ParkPA16802 United States

We discuss a new classical action that enables efficient computation of the gluonic tree amplitudes but does not contain any triple point vertices. This new formulation is obtained via a canonical transformation of the light-cone Yang-Mills action, with the field transformations based on Wilson line functionals. In addition to MHV vertices, the action contains also NkMHV vertices, where 1 ≤ k ≤ n − 4, and n is the number of external legs. We computed tree-level amplitudes up to 8 gluons and found agreement with standard results. The classical action is however not sufficient to obtain rational parts of amplitudes, in particular the finite amplitudes with all same helicity gluons. In order to systematically develop quantum corrections to this new action, we derive the one-loop effective action, in such a way there are no quantum contributions missing at one loop. Copyright © 2023, The Authors. All rights reserved.

关键词： Trees (mathematics)

Quality and Efficiency of Manual Annotation: Pre-annotation Bias

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arXiv 2023年

作者： Mikulová, Marie Straka, Milan Štěpánek, Jan Štěpánková, Barbora Hajič, Jan Institute of Formal and Applied Linguistics Computer Science School Faculty of Mathematics and Physics Charles University Prague Czech Republic

This paper presents an analysis of annotation using an automatic pre-annotation for a mid-level annotation complexity task - dependency syntax annotation. It compares the annotation efforts made by annotators using a pre-annotated version (with a high-accuracy parser) and those made by fully manual annotation. The aim of the experiment is to judge the final annotation quality when pre-annotation is used. In addition, it evaluates the effect of automatic linguistically-based (rule-formulated) checks and another annotation on the same data available to the annotators, and their influence on annotation quality and efficiency. The experiment confirmed that the pre-annotation is an efficient tool for faster manual syntactic annotation which increases the consistency of the resulting annotation without reducing its quality. Copyright © 2023, The Authors. All rights reserved.

关键词： Efficiency

Non-equilibrium dynamics of dipole-charged fields in the Proca theory

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arXiv 2023年

作者： Damski, Bogdan Jagiellonian University Faculty of Physics Astronomy and Applied Computer Science Lojasiewicza 11 Kraków30-348 Poland

We discuss the dynamics of field configurations encoded in the certain class of electric (magnetic) dipole-charged states in the Proca theory of the real massive vector field. We construct such states so as to ensure that the long distance structure of the mean electromagnetic field in them is initially set by the formula describing the electromagnetic field of the electric (magnetic) dipole. We analyze then how such a mean electromagnetic field evolves in time. We find that far away from the center of the initial field configuration, the long range component of the mean electromagnetic field harmonically oscillates, which leads to the phenomenon of the periodic oscillations of the electric (magnetic) dipole moment. We also find that near the center of the initial field configuration, the mean electromagnetic field escapes from its initial arrangement and a spherical shock wave propagating with the speed of light appears in the studied system. A curious configuration of the axisymmetric mean electric field is found to accompany the mean magnetic field in magnetic dipole-charged states. Copyright © 2023, The Authors. All rights reserved.

关键词： Electromagnetic fields

Transport properties and doping evolution of the Fermi surface in cuprates

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arXiv 2023年

作者： Klebel-Knobloch, Benjamin Tabis, Wojciech Gala, Mateusz A. Barišić, Osor S. Sunko, Denis K. Barišić, Neven Institute of Solid State Physics TU Wien Vienna1040 Austria AGH University of Krakow Faculty of Physics and Applied Computer Science Krakow30-059 Poland Institute of Physics Bijenička cesta 46 ZagrebHR-10000 Croatia Department of Physics Faculty of Science University of Zagreb Bijenička cesta 32 ZagrebHR-10000 Croatia

Measured transport properties of three representative cuprates are reproduced within the paradigm of two electron subsystems, itinerant and localized. The localized subsystem evolves continuously from the Cu 3d9 hole at half-filling and corresponds to the (pseudo)gapped parts of the Fermi surface. The itinerant subsystem is observed as a pure Fermi liquid (FL) with material-independent universal mobility across the doping/temperature phase diagram. The localized subsystem affects the itinerant one in our transport calculations solely by truncating the textbook FL integrals to the observed (doping- and temperature-dependent) Fermi arcs. With this extremely simple picture, we obtain the measured evolution of the resistivity and Hall coefficients in all three cases considered, including LSCO which undergoes a Lifshitz transition in the relevant doping range, a complication which turns out to be superficial. Our results imply that prior to evoking polaronic, quantum critical point, quantum dissipation, or even more exotic scenarios for the evolution of transport properties in cuprates, Fermi-surface properties must be addressed in realistic detail. © 2023, CC BY.

关键词： Transport properties