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Hamiltonian Lattice Formulation of Compact Maxwell-Chern-Simons Theory

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arXiv 2024年

作者： Peng, Changnan Diamantini, Maria Cristina Funcke, Lena Ali Hassan, Syed Muhammad Jansen, Karl Kühn, Stefan Luo, Di Naredi, Pranay Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States NiPS Laboratory INFN and Dipartimento di Fisica e Geologia University of Perugia Via A. Pascoli PerugiaI-06100 Italy University of Bonn Nussallee 14-16 Bonn53115 Germany Computation-Based Science and Technology Research Center The Cyprus Institute 20 Kavafi Street Nicosia2121 Cyprus CQTA Deutsches Elektronen-Synchrotron DESY Platanenallee 6 Zeuthen15738 Germany The NSF AI Institute for Artificial Intelligence and Fundamental Interactions Department of Physics Harvard University CambridgeMA02138 United States

In this paper, a Hamiltonian lattice formulation for 2+1D compact Maxwell-Chern-Simons theory is derived. We analytically solve this theory and demonstrate that the mass gap in the continuum limit matches the well-known continuum formula. Our formulation preserves topological features such as the quantization of the Chern-Simons level, the degeneracy of energy eigenstates, the non-trivial properties of Wilson loops, and the mutual and self statistics of anyons. This work lays the groundwork for future Hamiltonian-based simulations of Maxwell-Chern-Simons theory on classical and quantum computers. Copyright © 2024, The Authors. All rights reserved.

关键词： Hamiltonians

Collisional-model quantum trajectories for entangled-qubit environments

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Physical Review A 2022年第2期106卷 022202-022202页

作者： Shakib Daryanoosh Alexei Gilchrist Ben Q. Baragiola Centre for Engineered Quantum Systems Department of Physics and Astronomy Macquarie University Sydney NSW 2122 Australia Department of Physics University of Oxford Clarendon Laboratory Parks Road Oxford OX1 3PU United Kingdom Department of Physics University of Western Australia Crawley WA 6009 Australia Center for Gravitational Physics and Quantum Information (CGPQI) Yukawa Institute for Theoretical Physics Kyoto University Kitashirakawa Oiwakecho Sakyo-ku Kyoto 606-8502 Japan Centre for Quantum Computation and Communication Technology School of Science RMIT University Melbourne Victoria 3001 Australia

We study the dynamics of quantum systems interacting with a stream of entangled-qubit pairs in the weak coupling limit. For a large class of two-qubit bath states, we present a detailed framework describing conditional dynamical maps for the system, known as quantum trajectories, that arise when the qubits are measured. Depending on the measurement basis, these quantum trajectories can be jump-type or diffusive-type, and can successively transfer entanglement from the bath qubits other quantum systems. They also exhibit features not present in standard quantum optical trajectories due to the fact that collisional models are not confined by the standard white-noise limit for optical-mode baths. As an example of this formalism, we consider the case of two remote two-level systems, where jump-type quantum trajectories herald the birth and death of entanglement.

关键词： Open quantum systems & decoherence Quantum entanglement Quantum optics

Biased Gottesman-Kitaev-Preskill repetition code

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arXiv 2022年

作者： Stafford, Matthew P. Menicucci, Nicolas C. Quantum Engineering Technology Labs H. H. Wills Physics Laboratory Department of Electrical and Electronic Engineering University of Bristol Bristol United Kingdom Quantum Engineering Centre for Doctoral Training H. H. Wills Physics Laboratory Department of Electrical and Electronic Engineering University of Bristol Bristol United Kingdom Centre for Quantum Computation and Communication Technology School of Science RMIT University Melbourne VIC3000 Australia

Continuous-variable quantum computing architectures based upon the Gottesman-Kitaev-Preskill (GKP) encoding have emerged as a promising candidate because one can achieve fault-tolerance with a probabilistic supply of GKP states and Gaussian operations. Furthermore, by generalising to rectangular-lattice GKP states, a bias can be introduced and exploited through concatenation with qubit codes that show improved performance under biasing. However, these codes (such as the XZZX surface code) still require weight-four stabiliser measurements and have complex decoding requirements to overcome. In this work, we study the code-capacity behaviour of a rectangularlattice GKP encoding concatenated with a repetition code under an isotropic Gaussian displacement channel. We find a numerical threshold of σ = 0.599 for the noise's standard deviation, which outperforms the biased GKP planar surface code with a trade-off of increased biasing at the GKP level. This is all achieved with only weight-two stabiliser operators and simple decoding at the qubit level. Furthermore, with moderate levels of bias (aspect ratio ≤ 2.4) and nine or fewer data modes, significant reductions in logical error rates can still be achieved for σ ≤ 0.3, opening the possibility of using GKP-biased repetition codes as a simple low-level qubit encoding for further concatenation. Copyright © 2022, The Authors. All rights reserved.

关键词： Fault tolerance

Extreme subradiance from two-band Bloch oscillations in atomic arrays

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arXiv 2023年

作者： Wang, Luojia Wang, Da-Wei Yuan, Luqi Yang, Yaping Chen, Xianfeng State Key Laboratory of Advanced Optical Communication Systems and Networks School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Zhejiang Province Hangzhou310027 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China MOE Key Laboratory of Advanced Micro-Structured Materials School of Physics Science and Engineering Tongji University Shanghai200092 China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal University Jinan250358 China

Atomic arrays provide an important quantum optical platform with photon-mediated dipole-dipole interactions, which can be engineered to realize key applications in quantum information processing. A major obstacle for such application is the fast decay of the excited states. By controlling two-band Bloch oscillations in an atomic array under external magnetic field, here we show that exotic subradiance can be realized and maintained at a time scale upto 12 orders of magnitude larger than the spontaneous decay time in atomic arrays with the finite size. The key finding is to show a way for preventing the wavepacket of excited states scattering into the dissipative zone inside the free space light cone, which therefore leads to the excitation staying at a subradiant state for extremely long decay time. We show that such operation can be achieved by introducing a spatially linear potential from external magnetic field in atomic arrays and then manipulating interconnected two-band Bloch oscillations along opposite directions. Our results also point out the possibility of controllable switching between superradiant and subradiant states, which leads to potential applications in quantum storage. Copyright © 2023, The Authors. All rights reserved.

关键词： Excited states

Analytical solution for the surface states of the antiferromagnetic topological insulator MnBi2Te4

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Physical Review B 2020年第24期102卷 241406(R)-241406(R)页

作者： Hai-Peng Sun C. M. Wang Song-Bo Zhang Rui Chen Yue Zhao Chang Liu Qihang Liu Chaoyu Chen Hai-Zhou Lu X. C. Xie Department of Physics Harbin Institute of Technology Harbin 150001 China Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology (SUSTech) Shenzhen 518055 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen 518055 China Department of Physics Shanghai Normal University Shanghai 200234 China Institute for Theoretical Physics and Astrophysics University of Wurzberg D-97074 Wurzburg Germany International Center for Quantum Materials School of Physics Peking University Beijing 100871 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China Beijing Academy of Quantum Information Sciences West Building 3 No. 10 Xibeiwang East Road Haidian District Beijing 100193 China

Recently, the intrinsic magnetic topological insulator MnBi2Te4 has attracted great attention. It has an out-of-plane antiferromagnetic order, which is believed to open a sizable energy gap in the surface states. This gap, however, was not always observable in the latest angle-resolved photoemission spectroscopy (ARPES) experiments. To address this issue, we analytically derive an effective model for the two-dimensional (2D) surface states by starting from a three-dimensional (3D) Hamiltonian for bulk MnBi2Te4 and taking into account the spatial profile of the bulk magnetization. Our calculations suggest that the diminished surface gap may be caused by a much smaller and more localized intralayer ferromagnetic order. In addition, we calculate the spatial distribution and penetration depth of the surface states, which indicates that the surface states are mainly embedded in the first two septuple layers from the terminating surface. From our analytical results, the influence of the bulk parameters on the surface states can be found explicitly. Furthermore, we derive a k·p model for MnBi2Te4 thin films and show the oscillation of the Chern number between odd and even septuple layers. Our results will be helpful for the ongoing explorations of the MnBixTey family.

关键词： Quantum anomalous Hall effect Surface states Topological materials

Adapting a slit model to determine the aeroacoustic response of tube rows 51

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Adapting a slit model to determine the aeroacoustic response...

51st International Congress and Exposition on Noise Control Engineering, Internoise 2022

作者： Surendran, Aswathy Na, Wei Boakes, Charles Yang, Dong Morgans, Aimee S. Boij, Susann Department of Engineering Physics and Computation Technical University of Munich Garching85747 Germany School of Chemical and Physical Sciences Keele University StaffordshireST5 5BG United Kingdom Department of Mechanics and Maritime Sciences Chalmers University of Technology GothenburgSE-41296 Sweden Department of Mechanical Engineering Imperial College London LondonSW7 2AZ United Kingdom Department of Mechanics and Aerospace Engineering Southern University of Science and Technology Shenzhen518055 China KTH Royal Institute of Technology Marcus Wallenberg laboratory for Sound and Vibration Research Dept. of Engineering Mechanics StockholmSE-10044 Sweden

ISBN: (纸本)9781906913427

Cylindrical tubes in cross-flow, like the ones found in heat exchangers, are excellent acoustic dampers and as such have the potential to mitigate thermoacoustic instabilities. Flow separation and vortex shedding downstream of the tube row are key to significantly enhancing sound attenuation. However, constructing an analytical solution for the aeroacoustic response of tube rows in cross-flow is very challenging owing to the complex flow structure, vortex shedding and coupling with acoustics. To overcome this, we propose the adaptation of a slit model for tube row acoustic scattering (aeroacoustic response) predictions at low Strouhal numbers. The slit model was modified such that the loss coefficients across the slit and the tube row matches. The model is then validated against numerical predictions using Linearised Navier Stokes Equations and experimental measurements. The predictions for both magnitude and phase for transmission and reflection coefficients agree well with the simulations and experiments. © 2022 Internoise 2022 - 51st International Congress and Exposition on Noise Control Engineering. All rights reserved.

关键词： Vortex shedding

Scalar, vector, and tensor form factors for the pion and kaon from lattice QCD

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Physical Review D 2022年第5期105卷 054502-054502页

作者： Constantia Alexandrou Simone Bacchio Ian Cloët Martha Constantinou Joseph Delmar Kyriakos Hadjiyiannakou Giannis Koutsou Colin Lauer Alejandro Vaquero Department of Physics University of Cyprus P.O. Box 20537 1678 Nicosia Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Street Nicosia 2121 Cyprus Physics Division Argonne National Laboratory Lemont Illinois 60439 USA Department of Physics Temple University 1925 N. 12th Street Philadelphia Pennsylvania 19122-1801 USA Department of Physics and Astronomy University of Utah Salt Lake City Utah 84112 USA

We present a calculation of the scalar, vector, and tensor form factors for the pion and kaon in lattice QCD. We use an ensemble of two degenerate light, a strange and a charm quark (Nf=2+1+1) of maximally twisted mass fermions with clover improvement. The corresponding pion and kaon masses are about 265 MeV and 530 MeV, respectively. The calculation is done in both rest and boosted frames obtaining data for four-vector momentum transfer squared up to −q2=2.5 GeV2 for the pion and 3 GeV2 for the kaon. The excited-states effects are studied by analyzing six values of the source-sink time separation for the rest frame (1.12–2.23 fm) and for four values for the boosted frame (1.12–1.67 fm). The lattice data are renormalized nonperturbatively and the results for the scheme- and scale-dependent scalar and tensor form factors are presented in the MS¯ scheme at a scale of 2 GeV. We apply different parametrizations to describe q2-dependence of the form factors to extract the scalar, vector, and tensor radii, as well as the tensor anomalous magnetic moment. We compare the pion and kaon form factors to study SU(3) flavor symmetry breaking effects. By combining the data for the vector and tensor form factors we also obtain the lowest moment of the densities of transversely polarized quarks in the impact parameter space. Finally, we give an estimate for the average transverse shift in the y direction for polarized quarks in the x direction.

关键词： Lattice QCD

Tunable even- and odd-denominator fractional quantum Hall states in trilayer graphene

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arXiv 2023年

作者： Chen, Yiwei Huang, Yan Li, Qingxin Tong, Bingbing Kuang, Guangli Xi, Chuanying Watanabe, Kenji Taniguchi, Takashi Liu, Guangtong Zhu, Zheng Lu, Li Zhang, Fu-Chun Wu, Ying-Hai Wang, Lei National Laboratory of Solid-State Microstructures School of Physics Nanjing University Nanjing210093 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China Hefei National Laboratory Hefei230088 China Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory of the Chinese Academy of Science Hefei230031 China Research Center for Electronic and Optical Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Songshan Lake Materials Laboratory Dongguan523808 China Kavli Institute of Theoretical Sciences University of Chinese Academy of Sciences Beijing100049 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100049 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China School of Physics Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan430074 China

The fractional quantum Hall (FQH) states are exotic quantum many-body phases whose elementary charged excitations are neither bosons nor fermions but anyons, obeying fractional braiding statistics. While most FQH states are believed to have Abelian anyons, the Moore-Read type states with even denominators, appearing at half filling of a Landau level (LL), are predicted to possess non-Abelian excitations with appealing potentials in topological quantum computation. These states, however, depend sensitively on the orbital contents of the single-particle LL wave-function and the mixing between different LLs. Although they have been observed in a few materials, their non-Abelian statistics still awaits experimental confirmation. Here we show magnetotransport measurements on Bernal-stacked trilayer graphene (TLG), whose unique multiband structure facilitates the interlaced LL mixing, which can be controlled by external magnetic and displacement fields. We observe a series of robust FQH states including even-denominator ones at filling factors ν = −9/2, −3/2, 3/2 and 9/2. In addition, we are able to finetune the LL mixing and crossings to drive quantum phase transitions of these half-filling states and their neighboring odd-denominator ones, exhibiting a related emerging and waning behavior. Our results establish TLG as a controllable system for tuning the weights of LL orbitals and mixing strength, and a fresh platform to seek for non-Abelian quasi-particles. © 2023, CC BY.

关键词： Graphene

Observation of Thermalization and Information Scrambling in a Superconducting Quantum Processor

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Physical Review Letters 2022年第16期128卷 160502-160502页

作者： Qingling Zhu Zheng-Hang Sun Ming Gong Fusheng Chen Yu-Ran Zhang Yulin Wu Yangsen Ye Chen Zha Shaowei Li Shaojun Guo Haoran Qian He-Liang Huang Jiale Yu Hui Deng Hao Rong Jin Lin Yu Xu Lihua Sun Cheng Guo Na Li Futian Liang Cheng-Zhi Peng Heng Fan Xiaobo Zhu Jian-Wei Pan Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics University of Science and Technology of China Hefei Anhui 230026 China Shanghai Branch CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of China Shanghai 201315 China Shanghai Research Center for Quantum Sciences Shanghai 201315 China Institute of Physics Chinese Academy of Sciences Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100190 China Theoretical Quantum Physics Laboratory RIKEN Cluster for Pioneering Research Wako-shi Saitama 351-0198 Japan Songshan Lake Materials Laboratory Dongguan 523808 Guangdong China CAS Center for Excellent in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

Understanding various phenomena in nonequilibrium dynamics of closed quantum many-body systems, such as quantum thermalization, information scrambling, and nonergodic dynamics, is crucial for modern physics. Using a ladder-type superconducting quantum processor, we perform analog quantum simulations of both the XX-ladder model and the one-dimensional XX model. By measuring the dynamics of local observables, entanglement entropy, and tripartite mutual information, we signal quantum thermalization and information scrambling in the XX ladder. In contrast, we show that the XX chain, as free fermions on a one-dimensional lattice, fails to thermalize to the Gibbs ensemble, and local information does not scramble in the integrable channel. Our experiments reveal ergodicity and scrambling in the controllable qubit ladder, and open the door to further investigations on the thermodynamics and chaos in quantum many-body systems.

关键词： Eigenstate thermalization Entanglement entropy Quantum simulation Superconducting qubits