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Complexity-constrained quantum thermodynamics

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arXiv 2024年

作者： Munson, Anthony Kothakonda, Naga Bhavya Teja Haferkamp, Jonas Halpern, Nicole Yunger Eisert, Jens Faist, Philippe Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States Department of Physics University of Maryland College ParkMD20742 United States Physics Department Universitat Autònoma de Barcelona Bellaterra Barcelona08193 Spain Dahlem Center for Complex Quantum Systems Freie Universität Berlin Berlin14195 Germany School of Engineering and Applied Sciences Harvard University MA02134 United States Institute for Physical Science and Technology University of Maryland College ParkMD20742 United States

quantum complexity measures the difficulty of realizing a quantum process, such as preparing a state or implementing a unitary. We present an approach to quantifying the thermodynamic resources required to implement a process if the process’s complexity is restricted. We focus on the prototypical task of information erasure, or Landauer erasure, wherein an n-qubit memory is reset to the all-zero state. We show that the minimum thermodynamic work required to reset an arbitrary state, via a complexity-constrained process, is quantified by the state’s complexity entropy. The complexity entropy therefore quantifies a trade-off between the work cost and complexity cost of resetting a state. If the qubits have a nontrivial (but product) Hamiltonian, the optimal work cost is determined by the complexity relative entropy. The complexity entropy quantifies the amount of randomness a system appears to have to a computationally limited observer. Similarly, the complexity relative entropy quantifies such an observer’s ability to distinguish two states. We prove elementary properties of the complexity (relative) entropy and determine the complexity entropy’s behavior under random circuits. Also, we identify information-theoretic applications of the complexity entropy. The complexity entropy quantifies the resources required for data compression if the compression algorithm must use a restricted number of gates. We further introduce a complexity conditional entropy, which arises naturally in a complexity-constrained variant of information-theoretic decoupling. Assuming that this entropy obeys a conjectured chain rule, we show that the entropy bounds the number of qubits that one can decouple from a reference system, as judged by a computationally bounded referee. Overall, our framework extends the resource-theoretic approach to thermodynamics to integrate a notion of time, as quantified by complexity. © 2024, CC BY.

关键词： Entropy

Equilibrium and non-equilibrium dynamics of a hole in a bilayer antiferromagnet

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arXiv 2022年

作者： Nyhegn, Jens Havgaard Nielsen, Kristian K. Bruun, Georg M. Center for Complex Quantum Systems Department of Physics and Astronomy Aarhus University Ny Munkegade Aarhus C DK-8000 Denmark Max-Planck Institute for Quantum Optics Hans-Kopfermann-Str. 1 GarchingD-85748 Germany Shenzhen Institute for Quantum Science and Engineering Department of Physics Southern University of Science and Technology Shenzhen518055 China

The dynamics of charge carriers in lattices of quantum spins is a long standing and fundamental problem. Recently, a new generation of quantum simulation experiments based on atoms in optical lattices has emerged that gives unprecedented insights into the detailed spatial and temporal dynamics of this problem, which compliments earlier results from condensed matter experiments. Focusing on observables accessible in these new experiments, we explore here the equilibrium as well as non-equilibrium dynamics of a mobile hole in two coupled antiferromagnetic spin lattices. Using a self-consistent Born approximation, we calculate the spectral properties of the hole in the bilayer and extract the energy bands of the quasiparticles, corresponding to magnetic polarons that are either symmetric or anti-symmetric under layer exchange. These two kinds of polarons are degenerate at certain momenta due to the antiferromagnetic symmetry, and we, furthermore, examine how the momentum of the ground state polaron depends on the interlayer coupling strength. The long time dynamics of a hole initially created in one layer is shown to be characterised by oscillations between the two layers with a frequency given by the energy difference between the symmetric and the anti-symmetric polaron. We finally demonstrate that the expansion velocity of a hole initially created at a given lattice site is governed by the ballistic motion of polarons. It moreover depends non-monotonically on the interlayer coupling, eventually increasing as a quantum phase transition to a disordered state is approached. © 2022, CC BY.

关键词： Ground state

Coherent cellular dynamical mean-field theory: a real-space quantum embedding approach to disorder in strongly correlated electron systems

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arXiv 2025年

作者： Tscheppe, Patrick Klett, Marcel Menke, Henri Andergassen, Sabine Enderlein, Niklas Hansmann, Philipp Schäfer, Thomas Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 Stuttgart70569 Germany Department of Physics Columbia University 538 West 120th Street New YorkNY10027 United States Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Institute of Information Systems Engineering TU Wien Vienna1040 Austria Institute of Solid State Physics TU Wien Vienna1040 Austria Department of Physics Friedrich-Alexander-Universität Erlangen/Nürnberg Erlangen91058 Germany

We formulate a quantum embedding algorithm in real-space for the simultaneous theoretical treatment of nonlocal electronic correlations and disorder, the coherent cellular dynamical mean-field theory (C-CDMFT). This algorithm combines the molecular coherent potential approximation with the cellular dynamical mean-field theory. After a pedagogical introduction to quantum embedding theories for disordered and interacting electron systems, and a detailed discussion of its work flow, we present first results from C-CDMFT for the half-filled two-dimensional Anderson-Hubbard model on a square lattice: (i) the analysis of its Mott metal-insulator transition as a function of disorder strength, and (ii) the impact of different types of disorder on its magnetic phase diagram. For the latter, by means of a "disorder diagnostics", we are able to precisely identify the contributions of different disorder configurations to the system’s magnetic response. Copyright © 2025, The Authors. All rights reserved.

关键词： Metal insulator transition

Design monolayer iodinenes based on halogen bond and tiling theory

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arXiv 2023年

作者： Yu, Kejun Fu, Botao Zhang, Runwu Ma, Da-Shuai Li, Xiao-Ping Yu, Zhi-Ming Liu, Cheng-Cheng Yao, Yugui Liu, Yichen School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China College of Physics and Electronic Engineering Center for Computational Sciences Sichuan Normal University Chengdu610068 China Institute for Structure and Function Department of Physics Chongqing Key Laboratory for Strongly Coupled Physics Chongqing University Chongqing400044 China Center of Quantum materials and devices Chongqing University Chongqing400044 China School of Physical Science and Technology Inner Mongolia University Hohhot010021 China

Xenes, two-dimensional (2D) monolayers composed of a single element, with graphene as a typical representative, have attracted widespread attention. Most of the previous Xenes, X from group-IIIA to group-VIA elements have bonding characteristics of covalent bonds. In this work, we for the first time unveil the pivotal role of a halogen bond, which is a distinctive type of bonding with interaction strength between that of a covalent bond and a van der Waals interaction, in 2D group-VIIA monolayers. Combing the ingenious non-edge-to-edge tiling theory and state-of-the-art ab initio method with refined local density functional M06-L, we provide a precise and effective bottom-up construction of 2D iodine monolayer sheets, iodinenes, primarily governed by halogen bonds, and successfully design a category of stable iodinenes, encompassing herringbone, Pythagorean, gyrated truncated hexagonal, i.e. diatomic-kagome, and gyrated hexagonal tiling pattern. These iodinene structures exhibit a wealth of properties, such as nontrivial novel topology, flat bands and fascinating optical characteristics, offering valuable insights and guidance for future experimental investigations. Our work not only unveils the unexplored halogen bonding mechanism in 2D materials but also opens a new avenue for designing other non-covalent bonding 2D materials. © 2023, CC BY.

关键词： Monolayers

Probing rotational decoherence with a trapped-ion planar rotor

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arXiv 2023年

作者： Glikin, Neil Stickler, Benjamin A. Tollefsen, Ryan Mouradian, Sara Yadav, Neha Urban, Erik Hornberger, Klaus Häffner, Hartmut Department of Physics University of California Berkeley BerkeleyCA94720 United States Challenge Institute for Quantum Computation University of California Berkeley BerkeleyCA94720 United States Institute for Complex Quantum Systems Center for Integrated Quantum Science and Technology Ulm University Albert-Einstein-Allee 11 Ulm89069 Germany Department of Electrical and Computer Engineering University of Washington SeattleWA98195 United States University of Duisburg-Essen Faculty of Physics Lotharstraße 1 Duisburg47057 Germany

The quantum rotor is one of the simplest model systems in quantum mechanics, but only in recent years has theoretical work revealed general fundamental scaling laws for its decoherence. For example, a superposition of orientations decoheres at a rate proportional to the sine squared of the angle between them. Here we observe scaling laws for rotational decoherence dynamics for the first time, using a 4 µm-diameter planar rotor composed of two Paul-trapped ions. We prepare the rotational motion of the ion crystal into superpositions of angular momentum with well-defined differences ranging from 1 − 3 ℏ, and measure the rate of decoherence. We also tune the system-environment interaction strength by introducing resonant electric field noise. The observed scaling relationships for decoherence are in excellent agreement with recent theoretical work, and are directly relevant to the growing development of rotor-based quantum applications. © 2023, CC BY.

关键词： Trapped ions

Levitated Optomechanics with Meta-Atoms

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arXiv 2022年

作者： Lepeshov, Sergei Meyer, Nadine Maurer, Patrick Romero-Isart, Oriol Quidant, Romain School of Physics and Engineering ITMO University Saint Petersburg Russia Nanophotonic Systems Laboratory Department of Mechanical and Process Engineering ETH Zurich Zurich8092 Switzerland Quantum Center ETH Zurich Zurich8083 Switzerland Institute for Quantum Optics and Quantum Information The Austrian Academy of Sciences InnsbruckA-6020 Austria Institute for Theoretical Physics University of Innsbruck InnsbruckA-6020 Austria

We propose to introduce additional control in levitated optomechanics by trapping a meta-atom, i.e. a subwavelength and high-permittivity dielectric particle supporting Mie resonances. In particular, we theoretically demonstrate that optical levitation and center-of-mass ground-state cooling of silicon nanoparticles in vacuum is not only experimentally feasible but it offers enhanced performance over widely used silica particles, in terms of trap frequency, trap depth and optomechanical coupling rates. Moreover, we show that, by adjusting the detuning of the trapping laser with respect to the particle’s resonance, the sign of the polarizability becomes negative, enabling levitation in the minimum of laser intensity e.g. at the nodes of a standing wave. The latter opens the door to trapping nanoparticles in the optical near-field combining red and blue-detuned frequencies, in analogy to two-level atoms, which is of interest for generating strong coupling to photonic nanostructures and short-distance force sensing. Copyright © 2022, The Authors. All rights reserved.

关键词： Atoms

Observation of oriented Landau levels in Berry dipole semimetals

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arXiv 2024年

作者： Mo, Qingyang Zheng, Riyi Lu, Cuicui Huang, Xueqin Liu, Zhengyou Zhang, Shuang New Cornerstone Science Laboratory Department of Physics University of Hong Kong 999077 Hong Kong Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China School of Physics and Optoelectronics South China University of Technology Guangzhou Guangdong510640 China Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education School of Physics and Technology Wuhan University Wuhan430072 China Department of Electrical & Electronic Engineering University of Hong Kong 999077 Hong Kong Quantum Science Center of Guangdong-Hong Kong-Macao Great Bay Area 3 Binlang Road Shenzhen China

Band crossing points, such as Weyl and Dirac points, play a crucial role in the topological classification of materials and guide the exploration of exotic topological phases. The Berry dipole, a three-dimensional band crossing point beyond the Chern class, hosts a dipolar Berry curvature field and gives rise to numerous nontrivial quantum geometric effects. It has been proposed that the Berry dipole exhibits oriented Landau levels, whose spectrum critically relies on the orientation of the applied magnetic field. However, experimental demonstration of this phenomenon has remained elusive. Here we experimentally demonstrate oriented Landau levels by carefully engineering an inhomogeneous acoustic lattice. We observe distinct Landau level spectra and different propagation properties when the orientation of the pseudomagnetic field is reversed. Notably, we discover a new type of helical zero modes whose existence critically depends on the magnetic field's orientation. Our work paves the way for studying band crossings beyond Chern-class crossing points, including Berry multipoles and even-dimensional monopoles. Furthermore, it offers new insight for exploring topological devices. © 2024, CC BY.

关键词： Fruits

quantum-Inspired Mean Field Probabilistic Model for Combinatorial Optimization Problems

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arXiv 2024年

作者： Huang, Yuhan Jin, Siyuan Zhang, Yichi Pan, Ling Shao, Qiming Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology 999077 Hong Kong Department of information systems The Hong Kong University of Science and Technology 999077 Hong Kong Department of Physics The Hong Kong University of Science and Technology 999077 Hong Kong IAS Center for Quantum Technologies The Hong Kong University of Science and Technology 999077 Hong Kong

Combinatorial optimization problems are pivotal across many fields. Among these, Quadratic Unconstrained Binary Optimization (QUBO) problems, central to fields like portfolio optimization, network design, and computational biology, are NP-hard and require exponential computational resources. To address these challenges, we develop a novel quantum-Inspired Mean Field (QIMF) probabilistic model that approximates solutions to QUBO problems with enhanced accuracy and efficiency. The QIMF model draws inspiration from quantum measurement principles and leverages the mean field probabilistic model. We incorporate a measurement grouping technique and an amplitude-based shot allocation strategy, both critical for optimizing cost functions with a polynomial speedup over traditional methods. Our extensive empirical studies demonstrate significant improvements in solution evaluation for large-scale problems of portfolio selection, the weighted maxcut problem, and the Ising model. Specifically, using S&P 500 data from 2022 and 2023, QIMF improves cost values by 152.8% and 12.5%, respectively, compared to the state-of-the-art baselines. Furthermore, when evaluated on increasingly larger datasets for QUBO problems, QIMF’s scalability demonstrates its potential for large-scale QUBO challenges. © 2024, CC BY.

关键词： Large datasets

Orbital Magneto-Nonlinear Anomalous Hall Effect in Kagome Magnet Fe3Sn2

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arXiv 2024年

作者： Wang, Lujunyu Zhu, Jiaojiao Chen, Haiyun Wang, Hui Liu, Jinjin Huang, Yue-Xin Jiang, Bingyan Zhao, Jiaji Shi, Hengjie Tian, Guang Wang, Haoyu Yao, Yugui Yu, Dapeng Wang, Zhiwei Xiao, Cong Yang, Shengyuan A. Wu, Xiaosong State Key Laboratory for Artificial Microstructure and Mesoscopic Physics Frontiers Science Center for Nano-optoelectronics Peking University Beijing100871 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore487372 Singapore Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore School of Physics Beijing Institute of Technology Beijing100081 China School of Sciences Great Bay University Dongguan523000 China Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems Beijing Institute of Technology Beijing100081 China Material Science Center Yangtze Delta Region Academy of Beijing Institute of Technology Jiaxing China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Institute of Applied Physics and Materials Engineering University of Macau Taipa China Department of Physics The University of Hong Kong Hong Kong HKU-UCAS Joint Institute of Theoretical and Computational Physics Hong Kong Collaborative Innovation Center of Quantum Matter Beijing100871 China Peking University Yangtze Delta Institute of Optoelectronics Jiangsu Nantong226010 China

It has been theoretically predicted that perturbation of the Berry curvature by electromagnetic fields gives rise to intrinsic nonlinear anomalous Hall effects that are independent of scattering. Two types of nonlinear anomalous Hall effects are expected. The electric nonlinear Hall effect has recently begun to receive attention, while very few studies are concerned with the magneto-nonlinear Hall effect. Here, we combine experiment and first-principles calculations to show that the kagome ferromagnet Fe3Sn2 displays such a magneto-nonlinear Hall effect. By systematic field angular and temperature-dependent transport measurements, we unambiguously identify a large anomalous Hall current that is linear in both applied in-plane electric and magnetic fields, utilizing a unique in-plane configuration. We clarify its dominant orbital origin and connect it to the magneto-nonlinear Hall effect. The effect is governed by the intrinsic quantum geometric properties of Bloch electrons. Our results demonstrate the significance of the quantum geometry of electron wave functions from the orbital degree of freedom and open up a new direction in Hall transport effects. © 2024, CC BY.

关键词： Magnetos