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Primitive quantum gates for dihedral gauge theories

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Physical Review D 2022年第11期105卷 114501-114501页

作者： M. Sohaib Alam Stuart Hadfield Henry Lamm Andy C. Y. Li Rigetti Computing Berkeley California 94701 USA Quantum Artificial Intelligence Laboratory (QuAIL) NASA Ames Research Center Moffett Field California 94035 USA USRA Research Institute for Advanced Computer Science (RIACS) Mountain View California 94043 USA Fermi National Accelerator Laboratory Batavia Illinois 60510 USA

We describe the simulation of dihedral gauge theories on digital quantum computers. The non-Abelian discrete gauge group DN—the dihedral group—serves as an approximation to U(1)×Z2 lattice gauge theory. In order to carry out such a lattice simulation, we detail the construction of efficient quantum circuits to realize basic primitives including the non-Abelian Fourier transform over DN, the trace operation, and the group multiplication and inversion operations. For each case the required quantum resources scale linearly or as low-degree polynomials in n=logN. We experimentally benchmark our gates on the Rigetti Aspen-9 quantum processor for the case of D4. The estimated fidelity of all D4 gates was found to exceed 80%.

关键词： Lattice field theory quantum algorithms quantum simulation

Macroscopic Tunneling Probe of Moiré Spin Textures in Twisted CrI3

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arXiv 2024年

作者： Yang, Bowen Patel, Tarun Cheng, Meixin Pichugin, Kostyantyn Tian, Lin Sherlekar, Nachiket Yan, Shaohua Fu, Yang Tian, Shangjie Lei, Hechang Reimer, Michael E. Okamoto, Junichi Tsen, Adam W. Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Department of Chemistry University of Waterloo WaterlooONN2L 3G1 Canada Department of Electrical and Computer Engineering University of Waterloo WaterlooN2L 3G1 Canada Department of Physics Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices Renmin University of China Beijing100872 China School of Materials Science and Engineering Anhui University Hefei230601 China Institute of Physics University of Freiburg Hermann-Herder-Str. 3 Freiburg79104 Germany EUCOR Centre for Quantum Science and Quantum Computing University of Freiburg Hermann-Herder-Str. 3 Freiburg79104 Germany

Various noncollinear spin textures and magnetic phases have been predicted in twisted two-dimensional CrI3 due to competing ferromagnetic (FM) and antiferromagnetic (AFM) interlayer exchange from moiré stacking — with potential spintronic applications even when the underlying material possesses a negligible Dzyaloshinskii–Moriya or dipole–dipole interaction. Recent measurements have shown evidence of coexisting FM and AFM layer order in small-twist-angle CrI3 bilayers and double bilayers. Yet, the nature of the magnetic textures remains unresolved and possibilities for their manipulation and electrical readout are unexplored. Here, we use tunneling magnetoresistance to investigate the collective spin states of twisted double-bilayer CrI3 under both out-of-plane and in-plane magnetic fields together with detailed micromagnetic simulations of domain dynamics based on magnetic circular dichroism. Our results capture hysteretic and anisotropic field evolutions of the magnetic states and we further uncover two distinct non-volatile spin textures (out-of-plane and in-plane domains) at ≈1° twist angle, with a different global tunneling resistance that can be switched by magnetic field. © 2024, CC BY-NC-ND.

关键词： Chromium compounds

What is nonclassical about uncertainty relations?

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arXiv 2022年

作者： Catani, Lorenzo Leifer, Matthew Scala, Giovanni Schmid, David Spekkens, Robert W. Electrical Engineering and Computer Science Department Technische Universität Berlin Berlin10587 Germany Institute for Quantum Studies Schmid College of Science and Technology Chapman University One University Drive OrangeCA92866 United States International Centre for Theory of Quantum Technologies University of Gdansk Gdansk80-308 Poland Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada

Uncertainty relations express limits on the extent to which the outcomes of distinct measurements on a single state can be made jointly predictable. The existence of nontrivial uncertainty relations in quantum theory is generally considered to be a way in which it entails a departure from the classical worldview. However, this perspective is undermined by the fact that there exist operational theories which exhibit nontrivial uncertainty relations but which are consistent with the classical worldview insofar as they admit of a generalized-noncontextual ontological model. This prompts the question of what aspects of uncertainty relations, if any, cannot be realized in this way and so constitute evidence of genuine nonclassicality. We here consider uncertainty relations describing the tradeoff between the predictability of a pair of binary-outcome measurements (e.g., measurements of Pauli X and Pauli Z observables in quantum theory). We show that, for a class of theories satisfying a particular symmetry property, the functional form of this predictability tradeoff is constrained by noncontextuality to be below a linear curve. Because qubit quantum theory has the relevant symmetry property, the fact that its predictability tradeoff describes a section of a circle is a violation of this noncontextual bound, and therefore constitutes an example of how the functional form of an uncertainty relation can witness contextuality. We also deduce the implications for a selected group of operational foils to quantum theory and consider the generalization to three measurements. © 2022, CC BY.

关键词： quantum theory

Reply to "Comment on 'Why interference phenomena do not capture the essence of quantum theory'"

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arXiv 2022年

作者： Catani, Lorenzo Leifer, Matthew Schmid, David Spekkens, Robert W. Electrical Engineering and Computer Science Department Technische Universität Berlin Berlin10587 Germany Institute for Quantum Studies Schmid College of Science and Technology Chapman University One University Drive OrangeCA92866 United States International Centre for Theory of Quantum Technologies University of Gdansk Gdansk80-308 Poland Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada

Our article [1] argues that the phenomenology of interference that is traditionally regarded as problematic does not, in fact, capture the essence of quantum theory-contrary to the claims of Feynman and many others. It does so by demonstrating the existence of a physical theory, which we term the "toy field theory", that reproduces this phenomenology but which does not sacrifice the classical worldview. In their Comment [2], Hance and Hossenfelder dispute our claim. Correcting mistaken claims found therein and responding to their criticisms provides us with an opportunity to further clarify some of the ideas in our article. © 2022, CC BY.

关键词： Toys

Aspects of the phenomenology of interference that are genuinely nonclassical

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arXiv 2022年

Interference phenomena are often claimed to resist classical explanation. However, such claims are undermined by the fact that the specific aspects of the phenomenology upon which they are based can in fact be reproduced in a noncontextual ontological model [Catani et al. quantum 7, 1119 (2023)]. This raises the question of what other aspects of the phenomenology of interference do in fact resist classical explanation. We answer this question by demonstrating that the most basic quantum wave-particle duality relation, which expresses the precise trade-off between path distinguishability and fringe visibility, cannot be reproduced in any noncontextual model. We do this by showing that it is a specific type of uncertainty relation, and then leveraging a recent result establishing that noncontextuality restricts the functional form of this uncertainty relation [Catani et al. Phys. Rev. Lett. 129, 240401]. Finally, we discuss what sorts of interferometric experiment can demonstrate contextuality via the wave-particle duality relation. © 2022, CC BY.

关键词： Visibility

Virtual quantum resource distillation: General framework and applications

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arXiv 2024年

作者： Takagi, Ryuji Yuan, Xiao Regula, Bartosz Gu, Mile Department of Basic Science The University of Tokyo Tokyo153-8902 Japan Nanyang Quantum Hub School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Center on Frontiers of Computing Studies Peking University Beijing100871 China School of Computer Science Peking University Beijing100871 China Stanford Institute for Theoretical Physics Stanford University StanfordCA94305 United States Wako Saitama351-0198 Japan Department of Physics Graduate School of Science The University of Tokyo Bunkyo-ku Tokyo113-0033 Japan Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 Singapore117543 Singapore CNRS-UNS-NUS-NTU International Joint Research Unit UMI 3654 Singapore117543 Singapore

We develop the general framework of virtual resource distillation-an alternative distillation strategy proposed in Phys. Rev. Lett. 132, 050203 (2024), which extends conventional quantum resource distillation by integrating the power of classical postprocessing. The framework presented here is applicable not only to quantum states, but also dynamical quantum objects such as quantum channels and higher-order processes. We provide a general characterization and benchmarks for the performance of virtual resource distillation in the form of computable semidefinite programs as well as several operationally motivated quantities. We apply our general framework to various concrete settings of interest, including standard resource theories such as entanglement, coherence, and magic, as well as settings involving dynamical resources such as quantum memory, quantum communication, and non-Markovian dynamics. The framework of probabilistic distillation is also discussed. Copyright © 2024, The Authors. All rights reserved.

关键词： Distillation

Heavy quark potential and LQCD based quark condensate at finite magnetic field

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arXiv 2022年

作者： Nilima, Indrani Bandyopadhyay, Aritra Ghosh, Ritesh Ghosh, Sabyasachi Indian Institute of Technology Bhilai GEC Campus Sejbahar Chhattisgarh Raipur492015 India Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangzhou510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Southern Nuclear Science Computing Center South China Normal University Guangzhou510006 China Theory Division Saha Institute of Nuclear Physics HBNI 1/AF Bidhannagar Kolkata700064 India Homi Bhabha National Institute Anushaktinagar Maharashtra Mumbai400094 India

In the present work, we have studied heavy quarkonia potential in hot and magnetized quark gluon plasma. Inverse magnetic catalysis (IMC) effect is incorporated within the system through the magnetic field modified Debye mass by modifying the effective quark masses. We have obtained the real and imaginary part of the heavy quark potential in this new scenario. After the evaluation of the binding energy and the decay width we comment about the dissociation temperatures of the heavy quarkonia in presence of magnetic field. © 2022, CC BY.

关键词： Magnetic fields

Local quantum state marking

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Physical Review A 2022年第3期105卷 032407-032407页

作者： Samrat Sen Edwin Peter Lobo Sahil Gopalkrishna Naik Ram Krishna Patra Tathagata Gupta Subhendu B. Ghosh Sutapa Saha Mir Alimuddin Tamal Guha Some Sankar Bhattacharya Manik Banik School of Physics IISER Thiruvananthapuram Vithura Kerala 695551 India Physics and Applied Mathematics Unit Indian Statistical Institute 203 B.T. Road Kolkata 700108 India Department of Computer Science The University of Hong Kong Pokfulam road 999077 Hong Kong International Centre for Theory of Quantum Technologies (ICTQT) University of Gdask Bazynskiego 8 80-309 Gdansk Poland

We propose the task of local state marking (LSM), where some multipartite quantum states chosen randomly from a known set of states are distributed among spatially separated parties without revealing the identities of the individual states. The collaborative aim of the parties is to correctly mark the identities of states under the restriction that they can perform only local quantum operations (LOs) on their respective subsystems and can communicate with each other classically (CC)—popularly known as the operational paradigm of LOCC. While mutually orthogonal states can always be marked exactly under global operations, this is in general not the case under LOCC. We show that the LSM task is distinct from the vastly explored task of local state distinguishability (LSD)—perfect LSD always implies perfect LSM, whereas we establish that the converse does not hold in general. We also explore entanglement-assisted marking of states that are otherwise locally unmarkable, and we report intriguing entanglement-assisted catalytic LSM phenomena.

关键词： quantum correlations in quantum information quantum entanglement quantum information processing quantum protocols

A High Performance Compiler for Very Large Scale Surface Code Computations

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arXiv 2023年

作者： Watkins, George Nguyen, Hoang Minh Watkins, Keelan Pearce, Steven Lau, Hoi-Kwan Paler, Alexandru Department of Computer Science Aalto University Espoo00076 Finland School of Computing Science Simon Fraser University BurnabyBCV5A 1S6 Canada Department of Physics Simon Fraser University BurnabyBCV5A 1S6 Canada Quantum Algorithms Institute SurreyBCV3T 5X3 Canada

We present the first high performance compiler for very large scale quantum error correction: it translates an arbitrary quantum circuit to surface code operations based on lattice surgery. Our compiler offers an end to end error correction workflow implemented by a pluggable architecture centered around an intermediate representation of lattice surgery instructions. Moreover, the compiler supports customizable circuit layouts, can be used for quantum benchmarking and includes a quantum resource estimator. The compiler can process millions of gates using a streaming pipeline at a speed geared towards real-time operation of a physical device. We compiled within seconds 80 million logical surface code instructions, corresponding to a high precision Clifford+T implementation of the 128-qubit quantum Fourier Transform (QFT). Our code is open-sourced at https://***/latticesurgery-com. © 2023, CC BY.

关键词： Surgery