PRX quantum : a Physical Review journal最新文献_第7页

Quantum Criticality Under Decoherence or Weak Measurement 退相干或弱测量下的量子临界性

PRX quantum : a Physical Review journal Pub Date : 2023-01-12 DOI: 10.1103/prxquantum.4.030317

Jong Yeon Lee, Chao-Ming Jian, Cenke Xu

{"title":"Quantum Criticality Under Decoherence or Weak Measurement","authors":"Jong Yeon Lee, Chao-Ming Jian, Cenke Xu","doi":"10.1103/prxquantum.4.030317","DOIUrl":"https://doi.org/10.1103/prxquantum.4.030317","url":null,"abstract":"Decoherence inevitably happens when a quantum state is exposed to its environment, which can affect quantum critical points (QCP) in a nontrivial way. As was pointed out in recent literature on $(1+1)d$ conformal field theory (CFT), the effect of weak measurement can be mathematically mapped to the problem of boundary CFT. In this work, we focus on the $(2+1)d$ QCPs, whose boundary and defect effects have attracted enormous theoretical and numerical interests very recently. We focus on decoherence caused by weak measurements with and without post-selecting the measurement outcomes. Our main results are: (1) for an O(N) Wilson-Fisher QCP under weak measurement with post-selection, an observer would in general observe two different types of boundary/defect criticality with very different behaviors from the well-known Wilson-Fisher fixed points; in particular, it is possible to observe the recently proposed exotic\"extraordinary-log\"correlation. (2) An extra quantum phase transition can be driven by decoherence, if we consider quantities nonlinear with the decohered density matrix, such as the Renyi entropy. We demonstrate the connection between this transition to the information-theoretic transition driven by an error in the toric code model. (3) When there is no post-selection, though correlation functions between local operators remain the same as the undecohered pure state, nonlocal operators such as the\"disorder operator\"would have qualitatively distinct behaviors; and we also show that the decoherence can lead to confinement.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46353472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 19

Typical Correlation Length of Sequentially Generated Tensor Network States 序列生成张量网络状态的典型相关长度

PRX quantum : a Physical Review journal Pub Date : 2023-01-11 DOI: 10.1103/PRXQuantum.4.030330

D. Haag, F. Baccari, Georgios Styliaris

{"title":"Typical Correlation Length of Sequentially Generated Tensor Network States","authors":"D. Haag, F. Baccari, Georgios Styliaris","doi":"10.1103/PRXQuantum.4.030330","DOIUrl":"https://doi.org/10.1103/PRXQuantum.4.030330","url":null,"abstract":"The complexity of quantum many-body systems is manifested in the vast diversity of their correlations, making it challenging to distinguish the generic from the atypical features. This can be addressed by analyzing correlations through ensembles of random states, chosen to faithfully embody the relevant physical properties. Here, we focus on spins with local interactions, whose correlations are extremely well captured by tensor network states. Adopting an operational perspective, we define ensembles of random tensor network states in one and two spatial dimensions that admit a sequential generation. As such, they directly correspond to outputs of quantum circuits with a sequential architecture and random gates. In one spatial dimension, the ensemble explores the entire family of matrix product states, while in two spatial dimensions, it corresponds to random isometric tensor network states. We extract the scaling behavior of the average correlations between two subsystems as a function of their distance. Using elementary concentration results, we then deduce the typical case for measures of correlation such as the von Neumann mutual information and a measure arising from the Hilbert-Schmidt norm. We find for all considered cases that the typical behavior is an exponential decay (for both one and two spatial dimensions). We observe the consistent emergence of a correlation length that depends only on the underlying spatial dimension and not the considered measure. Remarkably, increasing the bond dimension leads to a higher correlation length in one spatial dimension but has the opposite effect in two spatial dimensions.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48590720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Ab Initio Derivation of Lattice-Gauge-Theory Dynamics for Cold Gases in Optical Lattices 光学格点中冷气体格点规范理论动力学的从头算推导

PRX quantum : a Physical Review journal Pub Date : 2023-01-09 DOI: 10.1103/PRXQuantum.4.020330

F. Surace, P. Fromholz, N. Oppong, M. Dalmonte, M. Aidelsburger

{"title":"Ab Initio\u0000 Derivation of Lattice-Gauge-Theory Dynamics for Cold Gases in Optical Lattices","authors":"F. Surace, P. Fromholz, N. Oppong, M. Dalmonte, M. Aidelsburger","doi":"10.1103/PRXQuantum.4.020330","DOIUrl":"https://doi.org/10.1103/PRXQuantum.4.020330","url":null,"abstract":"We introduce a method for quantum simulation of U$(1)$ lattice gauge theories coupled to matter, utilizing alkaline-earth(-like) atoms in state-dependent optical lattices. The proposal enables the study of both gauge and fermionic-matter fields without integrating out one of them in one and two dimensions. We focus on a realistic and robust implementation that utilizes the long-lived metastable clock state available in alkaline-earth(-like) atomic species. Starting from an $ab,initio$ modelling of the experimental setting, we systematically carry out a derivation of the target U$(1)$ gauge theory. This approach allows us to identify and address conceptual and practical challenges for the implementation of lattice gauge theories that - while pivotal for a successful implementation - have never been rigorously addressed in the literature: those include the specific engineering of lattice potentials to achieve the desired structure of Wannier functions, and the subtleties involved in realizing the proper separation of energy scales to enable gauge-invariant dynamics. We discuss realistic experiments that can be carried out within such a platform using the fermionic isotope $^{173}$Yb, addressing via simulations all key sources of imperfections, and provide concrete parameter estimates for relevant energy scales in both one- and two-dimensional settings.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46260299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Quantum Bayesian Inference in Quasiprobability Representations 拟概率表示中的量子贝叶斯推理

PRX quantum : a Physical Review journal Pub Date : 2023-01-05 DOI: 10.1103/PRXQuantum.4.020352

Aw Clive Cenxin, Kelvin Onggadinata, D. Kaszlikowski, V. Scarani

引用次数: 2

Transition Metal Ion Ensembles in Crystals as Solid-State Coherent Spin-Photon Interfaces: The Case of Nickel in Magnesium Oxide 作为固态相干自旋-光子界面的晶体中过渡金属离子团簇——以氧化镁中的镍为例

PRX quantum : a Physical Review journal Pub Date : 2022-12-30 DOI: 10.1103/prxquantum.4.030329

E. Poem, S. Gupta, I. Morris, K. Klink, L. Singh, T. Zhong, S. Nicley, J. Becker, O. Firstenberg

{"title":"Transition Metal Ion Ensembles in Crystals as Solid-State Coherent Spin-Photon Interfaces: The Case of Nickel in Magnesium Oxide","authors":"E. Poem, S. Gupta, I. Morris, K. Klink, L. Singh, T. Zhong, S. Nicley, J. Becker, O. Firstenberg","doi":"10.1103/prxquantum.4.030329","DOIUrl":"https://doi.org/10.1103/prxquantum.4.030329","url":null,"abstract":"We present general guidelines for finding solid-state systems that could serve as coherent electron spin-photon interfaces even at relatively high temperatures, where phonons are abundant but cooling is easier, and show that transition metal ions in various crystals could comply with these guidelines. As an illustrative example, we focus on divalent nickel ions in magnesium oxide. We perform electron spin resonance spectroscopy and polarization-sensitive magneto-optical fluorescence spectroscopy of a dense ensemble of these ions and find that (i) the ground-state electron spin stays coherent at liquid-helium temperatures for several microseconds, and (ii) there exists energetically well-isolated excited states which can couple to two ground state spin sub-levels via optical transitions of orthogonal polarizations. The latter implies that fast, coherent optical control over the electron spin is possible. We then propose schemes for optical initialization and control of the ground-state electron spin using polarized optical pulses, as well as two schemes for implementing a noise-free, broadband quantum-optical memory at near-telecom wavelengths in this material system.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48611627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Power of a Quasispin Quantum Otto Engine at Negative Effective Spin Temperature 准自旋量子奥托发动机在负有效自旋温度下的功率

PRX quantum : a Physical Review journal Pub Date : 2022-12-23 DOI: 10.1103/prxquantum.3.040334

Jens Nettersheim, Sabrina Burgardt, Q. Bouton, Daniel Adam, E. Lutz, A. Widera

引用次数: 1

Error-Detectable Bosonic Entangling Gates with a Noisy Ancilla 带噪声辅助的玻色子纠缠门的可探测误差

PRX quantum : a Physical Review journal Pub Date : 2022-12-21 DOI: 10.1103/prxquantum.4.020354

T. Tsunoda, James D. Teoh, W. D. Kalfus, Stijn J. de Graaf, Benjamin J. Chapman, Jacob C. Curtis, Neel Thakur, S. Girvin, R. Schoelkopf

{"title":"Error-Detectable Bosonic Entangling Gates with a Noisy Ancilla","authors":"T. Tsunoda, James D. Teoh, W. D. Kalfus, Stijn J. de Graaf, Benjamin J. Chapman, Jacob C. Curtis, Neel Thakur, S. Girvin, R. Schoelkopf","doi":"10.1103/prxquantum.4.020354","DOIUrl":"https://doi.org/10.1103/prxquantum.4.020354","url":null,"abstract":"Bosonic quantum error correction has proven to be a successful approach for extending the coherence of quantum memories, but to execute deep quantum circuits, high-fidelity gates between encoded qubits are needed. To that end, we present a family of error-detectable two-qubit gates for a variety of bosonic encodings. From a new geometric framework based on a\"Bloch sphere\"of bosonic operators, we construct $ZZ_L(theta)$ and $text{eSWAP}(theta)$ gates for the binomial, 4-legged cat, dual-rail and several other bosonic codes. The gate Hamiltonian is simple to engineer, requiring only a programmable beamsplitter between two bosonic qubits and an ancilla dispersively coupled to one qubit. This Hamiltonian can be realized in circuit QED hardware with ancilla transmons and microwave cavities. The proposed theoretical framework was developed for circuit QED but is generalizable to any platform that can effectively generate this Hamiltonian. Crucially, one can also detect first-order errors in the ancilla and the bosonic qubits during the gates. We show that this allows one to reach error-detected gate fidelities at the $10^{-4}$ level with today's hardware, limited only by second-order hardware errors.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45926467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Bonsai Algorithm: Grow Your Own Fermion-to-Qubit Mappings 盆景算法:生长自己的费米子到量子位映射

PRX quantum : a Physical Review journal Pub Date : 2022-12-19 DOI: 10.1103/PRXQuantum.4.030314

A. Miller, Zolt'an Zimbor'as, S. Knecht, S. Maniscalco, Guillermo Garc'ia-P'erez

{"title":"Bonsai Algorithm: Grow Your Own Fermion-to-Qubit Mappings","authors":"A. Miller, Zolt'an Zimbor'as, S. Knecht, S. Maniscalco, Guillermo Garc'ia-P'erez","doi":"10.1103/PRXQuantum.4.030314","DOIUrl":"https://doi.org/10.1103/PRXQuantum.4.030314","url":null,"abstract":"Fermion-to-qubit mappings are used to represent fermionic modes on quantum computers, an essential first step in many quantum algorithms for electronic structure calculations. In this work, we present a formalism to design flexible fermion-to-qubit mappings from ternary trees. We discuss in an intuitive manner the connection between the generating trees' structure and certain properties of the resulting mapping, such as Pauli weight and the delocalisation of mode occupation. Moreover, we introduce a recipe that guarantees Fock basis states are mapped to computational basis states in qubit space, a desirable property for many applications in quantum computing. Based on this formalism, we introduce the Bonsai algorithm, which takes as input the potentially limited topology of the qubit connectivity of a quantum device and returns a tailored fermion-to-qubit mapping that reduces the SWAP overhead with respect to other paradigmatic mappings. We illustrate the algorithm by producing mappings for the heavy-hexagon topology widely used in IBM quantum computers. The resulting mappings have a favourable Pauli weight scaling $mathcal{O}(sqrt{N})$ on this connectivity, while ensuring that no SWAP gates are necessary for single excitation operations.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41922221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

From Time-Reversal Symmetry to Quantum Bayes’ Rules 从时间反转对称性到量子贝叶斯规则

PRX quantum : a Physical Review journal Pub Date : 2022-12-15 DOI: 10.1103/PRXQuantum.4.020334

Arthur J. Parzygnat, J. Fullwood

引用次数: 13

Universal Qudit Gate Synthesis for Transmons Transmons的通用Qudit门合成

PRX quantum : a Physical Review journal Pub Date : 2022-12-08 DOI: 10.1103/PRXQuantum.4.030327

Laurin E. Fischer, A. Chiesa, F. Tacchino, D. Egger, S. Carretta, I. Tavernelli

{"title":"Universal Qudit Gate Synthesis for Transmons","authors":"Laurin E. Fischer, A. Chiesa, F. Tacchino, D. Egger, S. Carretta, I. Tavernelli","doi":"10.1103/PRXQuantum.4.030327","DOIUrl":"https://doi.org/10.1103/PRXQuantum.4.030327","url":null,"abstract":"Gate-based quantum computers typically encode and process information in two-dimensional units called qubits. Using $d$-dimensional qudits instead may offer intrinsic advantages, including more efficient circuit synthesis, problem-tailored encodings and embedded error correction. In this work, we design a superconducting qudit-based quantum processor wherein the logical space of transmon qubits is extended to higher-excited levels. We propose a universal gate set featuring a two-qudit cross-resonance entangling gate, for which we predict fidelities beyond $99%$ in the $d=4$ case of ququarts with realistic experimental parameters. Furthermore, we present a decomposition routine that compiles general qudit unitaries into these elementary gates, requiring fewer entangling gates than qubit alternatives. As proof-of-concept applications, we numerically demonstrate the synthesis of ${rm SU}(16)$ gates for noisy quantum hardware and an embedded error correction sequence that encodes a qubit memory in a transmon ququart to protect against pure dephasing noise. We conclude that universal qudit control -- a valuable extension to the operational toolbox of superconducting quantum information processing -- is within reach of current transmon-based architectures and has applications to near-term and long-term hardware.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42367027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6