The universal quantum computer is a device capable of simulating any physical system and represents a major goal for the field of quantum information science. Algorithms performed on such a device are predicted to offer significant gains for some important computational tasks. In the context of quantum information, "universal" refers to the ability to perform arbitrary unitary transformations in the system's computational space. The combination of arbitrary single-quantum-bit (qubit) gates with an entangling two-qubit gate is a gate set capable of achieving universal control of any number of qubits, provided that these gates can be performed repeatedly and between arbitrary pairs of qubits. Although gate sets have been demonstrated in several technologies, they have as yet been tailored toward specific tasks, forming a small subset of all unitary operators. Here we demonstrate a programmable quantum processor that realises arbitrary unitary transformations on two qubits, which are stored in trapped atomic ions. Using quantum state and process tomography, we characterise the fidelity of our implementation for 160 randomly chosen operations. This universal control is equivalent to simulating any pairwise interaction between spin-1/2 systems. A programmable multi-qubit register could form a core component of a large-scale quantum processor, and the methods used here are suitable for such a device.
A single programmable photonic circuit for universal quantum measurements
University of Science and Technology of China（中国科学技术大学）；Hefei National Laboratory（合肥国家实验室）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）
Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；IBM Research（IBM 研究院）；QuSoft；Institute for Logic, Language and Computation, University of Amsterdam（阿姆斯特丹大学逻辑、语言与计算研究所）；Korteweg-de Vries Institute for Mathematics, University of Amsterdam（阿姆斯特丹大学科特韦格-德弗里斯数学研究所）
In-orbit operation of a programmable quantum photonic processor
University of Vienna（维也纳大学）；QUBO Technology GmbH（QUBO技术有限公司）；Remote Sensing Technology Institute, German Aerospace Center (DLR)（德国航空航天中心遥感技术研究所）；Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche (IFN-CNR)（国家研究委员会光子学与纳米技术研究所）
Programmable Fermionic Quantum Processors with Globally Controlled Lattices
Institute for Theoretical Physics, University of Innsbruck（因斯布鲁克大学理论物理研究所）；Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences（奥地利科学院量子光学与量子信息研究所）；Max Planck Institute of Quantum Optics（马克斯·普朗克量子光学研究所）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）
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）
Active Learning on a Programmable Photonic Quantum Processor
Henan Key Laboratory of Quantum Information and Cryptography（河南省量子信息与密码重点实验室）；University of Science and Technology of China（中国科学技术大学）；Hefei National Research Center for Physical Sciences at the Microscale（合肥微尺度物质科学国家研究中心）；Shanghai Research Center for Quantum Science（上海量子科学研究中心）；CAS Center for Excellence in Quantum Information and Quantum Physics（中国科学院量子信息与量子科技创新研究院）；Hefei National Laboratory（合肥国家实验室）
Quantum continual learning on a programmable superconducting processor
Zhejiang University（浙江大学）；Tsinghua University（清华大学）；Shanghai Qi Zhi Institute（上海人工智能实验室）；Chinese Academy of Sciences（中国科学院）；Universiteit Leiden（莱顿大学）；Polish Academy of Sciences（波兰科学院）
Simulating Hamiltonian dynamics in a programmable photonic quantum processor using linear combinations of unitary operations
State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University（北京大学物理学院介观物理国家重点实验室）；Frontiers Science Center for Nano-optoelectronics & Collaborative Innovation Center of Quantum Matter, Peking University（北京大学纳米光子学与光电子前沿科学中心及量子物质协同创新中心）；Collaborative Innovation Center of Extreme Optics, Shanxi University（山西大学极端光学协同创新中心）；Peking University Yangtze Delta Institute of Optoelectronics（北京大学长三角光电科学研究院）；Hefei National Laboratory（合肥国家实验室）
Interplay of Confinement and Localization in a Programmable Rydberg Atom Chain
Jülich Supercomputing Centre, Forschungszentrum Jülich（于利希超级计算中心，于利希研究中心）；RWTH Aachen University（亚琛工业大学）；Department of Computer Science, University of Cologne（科隆大学计算机科学系）；Institute for Advanced Simulation, Forschungszentrum Jülich（于利希研究中心先进模拟研究所）；Jožef Stefan Institute（约瑟夫·斯蒂芬研究所）；CENN Nanocenter（CENN纳米中心）
