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Building a Fault-Tolerant quantum Computer Using Concatenated Cat Codes

PRX quantum 2022年第1期3卷 010329-010329页

作者： Christopher Chamberland Kyungjoo Noh Patricio Arrangoiz-Arriola Earl T. Campbell Connor T. Hann Joseph Iverson Harald Putterman Thomas C. Bohdanowicz Steven T. Flammia Andrew Keller Gil Refael John Preskill Liang Jiang Amir H. Safavi-Naeini Oskar Painter Fernando G.S.L. Brandão AWS Center for Quantum Computing Pasadena California 91125 USA IQIM California Institute of Technology Pasadena California 91125 USA Department of Physics Yale University New Haven Connecticut 06511 USA Pritzker School of Molecular Engineering The University of Chicago Illinois 60637 USA Department of Applied Physics and Ginzton Laboratory Stanford University Stanford California 94305 USA

We present a comprehensive architectural analysis for a proposed fault-tolerant quantum computer based on cat codes concatenated with outer quantum error-correcting codes. For the physical hardware, we propose a system of acoustic resonators coupled to superconducting circuits with a two-dimensional layout. Using estimated physical parameters for the hardware, we perform a detailed error analysis of measurements and gates, including cnot and Toffoli gates. Having built a realistic noise model, we numerically simulate quantum error correction when the outer code is either a repetition code or a thin rectangular surface code. Our next step toward universal fault-tolerant quantum computation is a protocol for fault-tolerant Toffoli magic state preparation that significantly improves upon the fidelity of physical Toffoli gates at very low qubit cost. To achieve even lower overheads, we devise a new magic state distillation protocol for Toffoli states. Combining these results together, we obtain realistic full-resource estimates of the physical error rates and overheads needed to run useful fault-tolerant quantum algorithms. We find that with around 1000 superconducting circuit components, one could construct a fault-tolerant quantum computer that can run circuits, which are currently intractable for classical computers. Hardware with 18 000 superconducting circuit components, in turn, could simulate the Hubbard model in a regime beyond the reach of classical computing.

关键词： quantum algorithms quantum benchmarking quantum error correction quantum gates Surface code quantum computing Topological quantum computing

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On demand single photon generation and coherent control of excitons from resonantly driven nanowire quantum dots

arXiv

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arXiv 2024年

作者： Gao, Jun Krishna, Govind Yeung, Edith Yu, Lingxi Gangopadhyay, Sayan Chan, Kai-Sum Huang, Chiao-Tzu Descamps, Thomas Reimer, Michael E. Poole, Philip J. Dalacu, Dan Zwiller, Val Elshaari, Ali W. KTH Royal Institute of Technology Department of Applied Physics Albanova University Centre Roslagstullbacken 21 Stockholm106 91 Sweden National Research Council of Canada OttawaONK1A 0R6 Canada University of Ottawa OttawaONK1N 6N5 Canada Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Electrical and Computer Engineering University of Toronto TorontoONM5S 3G4 Canada Quantum Bridge Technologies Inc. 108 College Street TorontoM5G 0C6 Canada Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Institute for Quantum Computing Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada

Coherent control of single photon sources is a key requirement for the advancement of photonic quantum technologies. Among them, nanowire-based quantum dot sources are popular due to their potential for on-chip hybrid integration. Here we demonstrate on-demand single-photon generation (g(2)(0)(X∗) = 0.078 and g(2)(0)(X) = 0.03) from resonantly excited InAsP/InP nanowire quantum dots and observe Rabi oscillations in the dot emission, indicating successful coherent manipulation of the excitonic states in the nanowire. We also measure a low emission time jitter for resonant excitation as compared to above-band excitation. This work addresses the long-standing challenge of resonantly exciting nanowire-quantum dots. It paves the way for hybrid quantum photonic integration, enabling spin-photon entanglement and matter memories on-chip. © 2024, CC BY.

关键词： Semiconductor quantum dots

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Distributed exact quantum algorithms for Deutsch-Jozsa problem

arXiv

引用

arXiv 2023年

作者： Li, Hao Qiu, Daowen Luo, Le Institute of Quantum Computing and Computer Theory School of Computer Science and Engineering Sun Yat-sen University Guangzhou510006 China The Guangdong Key Laboratory of Information Security Technology Sun Yat-sen University 510006 China School of Physics and Astronomy Sun Yat-sen University Zhuhai519082 China QUDOOR Technologies Inc. Guangzhou China

Deutsch-Jozsa (DJ) problem is one of the most important problems demonstrating the power of quantum algorithm. DJ problem can be described as a Boolean function f: {0, 1}n → {0, 1} with promising it is either constant or balanced, and the purpose is to determine which type it is. DJ algorithm can solve it exactly with one query. In this paper, we first discover the inherent structure of DJ problem in distributed scenario by giving a number of equivalence characterizations between f being constant (balanced) and some properties of f’s subfunctions, and then we propose three distributed exact quantum algorithms for solving DJ problem. Our algorithms have essential acceleration over distributed classical deterministic algorithm, and can be extended to the case of multiple computing nodes. Compared with DJ algorithm, our algorithms can reduce the number of qubits and the depth of circuit implementing a single query operator. Therefore, we find that the structure of problem should be clarified for designing distributed quantum algorithm to solve it. Copyright © 2023, The Authors. All rights reserved.

关键词： Boolean functions

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Generation of quantum phases of matter and finding a maximum-weight independent set of unit-disk graphs using Rydberg atoms

arXiv

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arXiv 2024年

作者： Farouk, Ahmed M. Beterov, I.I. Xu, Peng Ryabtsev, I.I. Faculty of Mechanics and Mathematics Novosibirsk State University Novosibirsk630090 Russia Laboratory of Nonlinear Resonant Processes and Laser Diagnostics Rzhanov Institute of Semiconductor Physics SB RAS Novosibirsk630090 Russia Department of Mathematics Faculty of Science Al-Azhar University Cairo11884 Egypt Faculty of Physics Novosibirsk State University Novosibirsk630090 Russia Department of Laser Physics Institute of Laser Physics SB RAS Novosibirsk630090 Russia Faculty of Physical Engineering Novosibirsk State Technical University Novosibirsk630073 Russia State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan430071 China Department of Quantum Computing Wuhan Institute of Quantum Technology Wuhan430206 China

Recent progress in quantum computing and quantum simulation of many-body systems with arrays of neutral atoms using Rydberg excitation has provided unforeseen opportunities towards computational advantage in solving various optimization problems. The problem of a maximum-weight independent set of unit-disk graphs is an example of an NP-hard optimization problem. It involves finding the largest set of vertices with the maximum sum of their weights for a graph which has edges connecting all pairs of vertices within a unit distance. This problem can be solved using quantum annealing with an array of interacting Rydberg atoms. For a particular graph, a spatial arrangement of atoms represents vertices of the graph, while the detuning from resonance at Rydberg excitation defines the weights of these vertices. The edges of the graph can be drawn according to the unit disk criterion. Maximum-weight independent sets can be obtained by applying a variational quantum adiabatic algorithm. We consider driving the quantum system of interacting atoms to the many-body ground state using a non-linear quasi-adiabatic profile for sweeping the Rydberg detuning. We also propose using a quantum wire which is a set of auxiliary atoms of a different chemical element to mediate strong coupling between the remote vertices of the graph. We investigate this effect for different lengths of the quantum wire. We also investigate the quantum phases of matter realizing commensurate and incommensurate phases in one- and two-dimensional spatial arrangements of the atomic array. Copyright © 2024, The Authors. All rights reserved.

关键词： Rydberg states

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quantum adiabatic doping for atomic Fermi-Hubbard quantum simulations

引用

Physical Review A 2021年第4期103卷 043320-043320页

作者： Jue Nan Jian Lin Yuchen Luo Bo Zhao Xiaopeng Li Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Hefei Anhui 230026 China State Key Laboratory of Surface Physics Institute of Nanoelectronics and Quantum Computing and Department of Physics Fudan University Shanghai 200433 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 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 Qi Zhi Institute Xuhui District Shanghai 200032 China

It is important to dope the antiferromagnetic state while preserving low entropy, in the quantum simulation of the Fermi-Hubbard model. In a recent work [Phys. Rev. Lett. 123, 233603 (2019)], we proposed a quantum adiabatic doping protocol using an incommensurate lattice potential, where its feasibility is demonstrated with a certain particle-doping fraction. Here, we carry out a systematic study of quantum adiabatic doping for a wide range of doping fractions including both particle doping and hole doping, with both commensurate and incommensurate cases considered. We find that there is still a localizationlike slowing-down problem even at commensurate fillings, and that it becomes less harmful in the hole-doped regime. With interactions, the adiabatic preparation is found to be more efficient because the interaction effect destabilizes localization. For both free and interacting cases, we find adiabatic doping has a better performance in the hole-doped regime than the particle-doped regime. We also investigate adiabatic doping starting from a half-filling Mott insulator, which is found to be more efficient for certain filling fractions.

关键词： Anderson localization Fermi gases Superconductivity Fermionic condensates Ultracold gases Electric moment Magnetic moment Density matrix renormalization group Extended Hubbard model Tensor network methods

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engineering the level structure of a giant artificial atom in waveguide quantum electrodynamics

引用

Physical Review A 2021年第2期103卷 023710-023710页

作者： A. M. Vadiraj Andreas Ask T. G. McConkey I. Nsanzineza C. W. Sandbo Chang Anton Frisk Kockum C. M. Wilson Institute for Quantum Computing and Electrical and Computer Engineering Department University of Waterloo Waterloo Ontario N2L 3G1 Canada Department of Microtechnology and Nanoscience Chalmers University of Technology 412 96 Gothenburg Sweden

engineering light-matter interactions at the quantum level has been central to the pursuit of quantum optics for decades. Traditionally, this has been done by coupling emitters, typically natural atoms and ions, to quantized electromagnetic fields in optical and microwave cavities. In these systems, the emitter is approximated as an idealized dipole, as its physical size is orders of magnitude smaller than the wavelength of light. Recently, artificial atoms made from superconducting circuits have enabled new frontiers in light-matter coupling, including the study of “giant” atoms which cannot be approximated as simple dipoles. Here, we explore an implementation of a giant artificial atom, formed from a transmon qubit coupled to propagating microwaves at multiple points along an open transmission line. The nature of this coupling allows the qubit radiation field to interfere with itself, leading to some striking giant-atom effects. For instance, we observe strong frequency-dependent couplings of the qubit energy levels to the electromagnetic modes of the transmission line. Combined with the ability to in situ tune the qubit energy levels, we show that we can modify the relative coupling rates of multiple qubit transitions by more than an order of magnitude. By doing so, we engineer a metastable excited state, allowing us to operate the giant transmon as an effective lambda system where we clearly demonstrate electromagnetically induced transparency.

关键词： Light-matter interaction quantum optics Superconductivity

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Controlling Synthetic Spin-Orbit Coupling in a Silicon quantum Dot with Magnetic Field

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Physical Review Applied 2021年第4期15卷 044042-044042页

作者： Xin Zhang Yuan Zhou Rui-Zi Hu Rong-Long Ma Ming Ni Ke Wang Gang Luo Gang Cao Gui-Lei Wang Peihao Huang Xuedong Hu Hong-Wen Jiang Hai-Ou Li Guang-Can Guo Guo-Ping Guo CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei Anhui 230026 China CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 20026 China Key Laboratory of Microelectronics Devices & Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Department of Physics University at Buffalo SUNY Buffalo New York 14260 USA Department of Physics and Astronomy University of California Los Angeles California 90095 USA Origin Quantum Computing Company Limited Hefei Anhui 230026 China

Tunable synthetic spin-orbit coupling (SSOC) is one of the key challenges in various quantum systems, such as ultracold atomic gases, topological superconductors, and semiconductor quantum dots. Here we experimentally demonstrate controlling the SSOC by investigating the anisotropy of spin-valley resonance in a silicon quantum dot. As we rotate the applied magnetic field in plane, we find a striking nonsinusoidal behavior of resonance amplitude that distinguishes SSOC from the intrinsic spin-orbit coupling (ISOC), and associate this behavior with the previously overlooked in-plane transverse magnetic field gradient. Moreover, by theoretically analyzing the experimentally measured SSOC field, we predict the quality factor of the spin qubit could be optimized if the orientation of the in-plane magnetic field is rotated away from the traditional working point.

关键词： Magnetic anisotropy quantum information with solid state qubits Spin blockade Spin-orbit coupling Valleytronics Double quantum dots Elemental semiconductors Electron spin resonance

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A two-stage solution to quantum process tomography: error analysis and optimal design

arXiv

引用

arXiv 2024年

作者： Xiao, Shuixin Wang, Yuanlong Zhang, Jun Dong, Daoyi Mooney, Gary J. Petersen, Ian R. Yonezawa, Hidehiro School of Engineering and Technology University of New South Wales CanberraACT2600 Australia University of Michigan–Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong University Shanghai200240 China School of Engineering The Australian National University CanberraACT2601 Australia Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China CIICADA Lab School of Engineering Australian National University ACT2601 Australia School of Physics The University of Melbourne ParkvilleVIC3010 Australia School of Physics University of Melbourne ParkvilleVIC3010 Australia School of Engineering Australian National University ACT2601 Australia RIKEN Center for Quantum Computing Japan Centre for Quantum Computation and Communication Technology Australian Research Council CanberraACT2600 Australia

quantum process tomography is a critical task for characterizing the dynamics of quantum systems and achieving precise quantum control. In this paper, we propose a two-stage solution for both trace-preserving and non-trace-preserving quantum process tomography. Utilizing a tensor structure, our algorithm exhibits a computational complexity of O(MLd2) where d is the dimension of the quantum system and M, L represent the numbers of different input states and measurement operators, respectively. We establish an analytical error upper bound and then design the optimal input states and the optimal measurement operators, which are both based on minimizing the error upper bound and maximizing the robustness characterized by the condition number. Numerical examples and testing on IBM quantum devices are presented to demonstrate the performance and efficiency of our algorithm. Copyright © 2024, The Authors. All rights reserved.

关键词： Error analysis

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Non-Gaussian quantum state generation by multi-photon subtraction at the telecommunication wavelength

arXiv

引用

arXiv 2023年

作者： Endo, Mamoru He, Ruofan Sonoyama, Tatsuki Takahashi, Kazuma Kashiwazaki, Takahiro Umeki, Takeshi Takasu, Sachiko Hattori, Kaori Fukuda, Daiji Fukui, Kosuke Takase, Kan Asavanant, Warit Marek, Petr Filip, Radim Furusawa, Akira Department of Applied Physics School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-8656 Japan Optical Quantum Computing Research Team RIKEN Center for Quantum Computing 2-1 Hirosawa Saitama Wako351-0198 Japan NTT Device Technology Labs. NTT Corporation 3-1 Morinosato Wakamiya Kanagawa Atsugi243-0198 Japan National Institute of Advanced Industrial Science and Technology Ibaraki Tsukuba305-8563 Japan AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory Ibaraki Tsukuba305-8563 Japan Department of Optics Palacky University 17. listopadu 1192/12 Olomouc77146 Czech Republic

In the field of continuous-variable quantum information processing, non-Gaussian states with negative values of the Wigner function are crucial for the development of a fault-tolerant universal quantum computer. While several non-Gaussian states have been generated experimentally, none have been created using ultrashort optical wave packets, which are necessary for high-speed quantum computation, in the telecommunication wavelength band where mature optical communication technology is available. In this paper, we present the generation of non-Gaussian states on wave packets with a short 8-ps duration in the 1545.32 nm telecommunication wavelength band using photon subtraction up to three photons. We used a low-loss, quasi-single spatial mode waveguide optical parametric amplifier, a superconducting transition edge sensor, and a phase-locked pulsed homodyne measurement system to observe negative values of the Wigner function without loss correction up to three-photon subtraction. These results can be extended to the generation of more complicated non-Gaussian states and are a key technology in the pursuit of high-speed optical quantum computation. Copyright © 2023, The Authors. All rights reserved.

关键词： Photons

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Decoherence of a tunable capacitively shunted flux qubit

arXiv

引用

arXiv 2023年

作者： Trappen, R. Dai, X. Yurtalan, M.A. Melanson, D. Tennant, D.M. Martinez, A.J. Tang, Y. Gibson, J. Grover, J.A. Disseler, S.M. Basham, J.I. Das, R. Kim, D.K. Melville, A.J. Niedzielski, B.M. Hirjibehedin, C.F. Serniak, K. Weber, S.J. Yoder, J.L. Oliver, W.D. Lidar, D.A. Lupascu, A. Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy Dartmouth College Hanover03755 United States Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Lincoln Laboratory Massachusetts Institute of Technology LexingtonMA02421 United States Departments of Electrical & Computer Engineering Chemistry and Physics Center for Quantum Information Science & Technology University of Southern California Los AngelesCA90089 United States Waterloo Institute for Nanotechnology University of Waterloo WaterlooONN2L 3G1 Canada

We present a detailed study of the coherence of a tunable capacitively-shunted flux qubit, designed for coherent quantum annealing applications. The measured relaxation at the qubit symmetry point is mainly due to intrinsic flux noise in the main qubit loop for qubit frequencies below ∼ 3 GHz. At higher frequencies, thermal noise in the bias line makes a significant contribution to the relaxation, arising from the design choice to experimentally explore both fast annealing and high-frequency control. The measured dephasing rate is primarily due to intrinsic low-frequency flux noise in the two qubit loops, with additional contribution from the low-frequency noise of control electronics used for fast annealing. The flux-bias dependence of the dephasing time also reveals apparent noise correlation between the two qubit loops, possibly due to non-local sources of flux noise or junction critical-current noise. Our results are relevant for ongoing efforts toward building superconducting quantum annealers with increased coherence. Copyright © 2023, The Authors. All rights reserved.

关键词： Qubits

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