We present a simple and powerful technique for finding a good error model for a quantum processor. The technique iteratively tests a nested sequence of models against data obtained from the processor, and keeps track of the best-fit model and its wildcard error (a quantification of the unmodeled error) at each step. Each best-fit model, along with a quantification of its unmodeled error, constitute a characterization of the processor. We explain how quantum processor models can be compared with experimental data and to each other. We demonstrate the technique by using it to characterize a simulated noisy 2-qubit processor.
Flexible Readout and Unconditional Reset for Superconducting Multi-Qubit Processors with Tunable Purcell Filters
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所凝聚态物理北京国家实验室）；School of Physics, University of Chinese Academy of Sciences（中国科学院大学物理学院）
In this paper, five techniques, for the representation of a digital image inside a quantum processor, are compared. The techniques are: flexible representation of quantum images (FRQI), novel enhanced quantum representation (NEQR), generalized quantum image representation (GQIR), multi-channel representation for quantum images (MCQI), and quantum Boolean image processing (QBIP). The comparison will be based on implementations on the Quirk simulator, and on the IBM Q Experience processors, from the point of view of performance, robustness (noise immunity), deterioration of the outcomes due to d…
Learning Lindblad Dynamics of a Superconducting Quantum Processor
University of Copenhagen（哥本哈根大学）；Niels Bohr Institute, University of Copenhagen（尼尔斯·玻尔研究所，哥本哈根大学）；Center for the Mathematics of Quantum Theory, MATH Department, University of Copenhagen（哥本哈根大学数学系量子理论数学中心）；Chalmers University of Technology（查尔姆斯理工大学）
Optimising Cryogenic Wiring for Microwave-frequency Millikelvin Quantum Processors
Sydney Quantum Academy（悉尼量子学院）；Centre for Quantum Software & Information, School of Mathematical & Physical Sciences, University of Technology Sydney（悉尼科技大学数学与物理科学学院量子软件与信息研究中心）
Observing quantum many-body dynamics in emergent curved spacetime using programmable quantum processors
University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；Princeton University（普林斯顿大学）；École Normale Supérieure (ENS), Université PSL（巴黎高等师范学院，巴黎文理研究大学）；IBM Quantum, IBM T.J. Watson Research Center（IBM量子，IBM托马斯·J·沃森研究中心）；MIT-IBM Watson AI Lab（麻省理工学院-IBM沃森人工智能实验室）；ETH Zurich（苏黎世联邦理工学院）
Scalable suppression of heating errors in large trapped-ion quantum processors
Center on Frontiers of Computing Studies, School of Computer Science, Peking University（北京大学计算机学院前沿计算研究中心）；Key Laboratory of Atomic and Subatomic Structure and Quantum Control (Ministry of Education), Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, School of Physics, South China Normal University（华南师范大学物理学院原子与亚原子结构及量子控制教育部重点实验室、广东省物质结构与基本相互作用卓越基础研究基地）；Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University（华南师范大学前沿物理研究院广东量子工程与量子材料重点实验室、粤港澳量子物质联合实验室）
We report on a flexible 300 mm process that optimally combines optical and electron beam lithography to fabricate silicon spin qubits. It enables on-the-fly layout design modifications while allowing devices with either n- or p-type ohmic implants, a pitch smaller than 100 nm, and uniform critical dimensions down to 30 nm with a standard deviation ~ 1.6 nm. Various n- and p-type qubits are characterized in a dilution refrigerator at temperatures ~ 10 mK. Electrical measurements demonstrate well-defined quantum dots, tunable tunnel couplings, and coherent spin control, which are essential requi…
Observation and Modulation of the Quantum Mpemba Effect on a Superconducting Quantum Processor
Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；RIKEN（理化学研究所）
Quench Spectroscopy of Magnetic Excitations on a Superconducting Quantum Processor
IBM Research（IBM研究院）；University of Southampton（南安普顿大学）；The Hartree Centre, STFC（STFC哈特里中心）；University College London（伦敦大学学院）；University of Oxford（牛津大学）；University of Edinburgh（爱丁堡大学）
Quantum computers, much like their classical counterparts, will likely benefit from flexible qubit encodings that can be matched to different tasks. For trapped ion quantum processors, a common way to access multiple encodings is to use multiple, co-trapped atomic species. Here, we outline an alternative approach that allows flexible encoding capabilities in single-species systems through the use of long-lived metastable states as an effective, programmable second species. We describe the set of additional trapped ion primitives needed to enable this protocol and show that they are compatible …
Fraunhofer Institute for Industrial Mathematics ITWM（弗劳恩霍夫工业数学研究所）；University of Kaiserslautern（凯泽斯劳滕大学）
In image processing, the amount of data to be processed grows rapidly, in particular when imaging methods yield images of more than two dimensions or time series of images. Thus, efficient processing is a challenge, as data sizes may push even supercomputers to their limits. Quantum image processing promises to encode images with logarithmically less qubits than classical pixels in the image. In theory, this is a huge progress, but so far not many experiments have been conducted in practice, in particular on real backends. Often, the precise conversion of classical data to quantum states, the …
