Article
Physics, Multidisciplinary
Daniel Malz, Adam Smith
Summary: The study demonstrates the implementation of time-dependent experiments on a single qubit using IBM Quantum Experience, achieving high fidelities of around 97%. The results suggest the possibility of realizing a wide class of Floquet Hamiltonians, providing new directions for theoretical and experimental research on many-body systems.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Wei Feng, Dexi Shao, Guo-Qiang Zhang, Qi-Ping Su, Jun-Xiang Zhang, Chui-Ping Yang
Summary: Motivated by recent realizations of 2D superconducting-qubit lattices, this study proposes a protocol to simulate the Hofstadter butterfly with synthetic gauge fields in superconducting circuits. By constructing a generalized Hofstadter model on zigzag lattices, a fractal energy spectrum similar to the original Hofstadter butterfly is achieved. The resonant frequencies of qubits are periodically modulated to engineer a synthetic gauge field, and a spectroscopic method is used to demonstrate the butterfly spectrum. Numerical simulations with realistic parameters confirm the presence of the butterfly spectrum. This proposal provides a promising approach for realizing the Hofstadter butterfly on the latest 2D superconducting-qubit lattices and will stimulate quantum simulation of novel properties induced by magnetic fields in superconducting circuits.
FRONTIERS OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
T-Q Cai, X-Y Han, Y-K Wu, Y-L Ma, J-H Wang, Z-L Wang, H-Y Zhang, H-Y Wang, Y-P Song, L-M Duan
Summary: The study reveals that in cross-resonance gates, spectator qubits have a significant impact on gate fidelity, depending on ZZ interactions and frequency detunings. The target spectator has a more serious impact, and the fidelity degradation is observed when both spectators have modest ZZ coupling to the computational qubits.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Nian-Quan Jiang, Xi Liang, Ming-Feng Wang
Summary: The article presents a powerful universal quantum processor designed using superconducting quantum circuits, featuring a symmetric all-to-all capacitive connection structure that allows for efficient suppression of unwanted crosstalk and high-quality couplings of qubits. This design may enable a practical programmable universal quantum computer within current technology.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2021)
Article
Physics, Applied
Tanay Roy, Ziqian Li, Eliot Kapit, DavidI. Schuster
Summary: Processing quantum information using qutrits as the fundamental unit offers computational advantages compared to qubit-based architectures. We demonstrate a fully programmable two-qutrit quantum processor using transmons. By implementing various algorithms, we show that our processor improves the success rates of quantum searches. Our results pave the way for building universal quantum computers using ternary quantum processors based on transmons.
PHYSICAL REVIEW APPLIED
(2023)
Article
Quantum Science & Technology
T. Kobayashi, T. Nakajima, K. Takeda, A. Noiri, J. Yoneda, S. Tarucha
Summary: This article presents the active reset of a silicon spin qubit using feedback control, based on quantum non-demolition (QND) readout and hardware data processing. The incorporation of cumulative readout technique enhances the initialization fidelity and suggests a pathway towards fault-tolerant quantum computation. These results provide a practical approach to achieve high-fidelity qubit operations in realistic devices.
NPJ QUANTUM INFORMATION
(2023)
Article
Multidisciplinary Sciences
R. D. Delaney, M. D. Urmey, S. Mittal, B. M. Brubaker, J. M. Kindem, P. S. Burns, C. A. Regal, K. W. Lehnert
Summary: Entangling microwave-frequency superconducting quantum processors through optical light at ambient temperature would enable secure communication and distributed quantum information processing. However, transducing quantum signals between these disparate regimes of the electro-magnetic spectrum remains an outstanding goal, and interfacing superconducting qubits with electro-optic transducers presents considerable challenges. In this study, a low-backaction electro-optomechanical transducer is used to readout a superconducting transmon qubit. The modular nature of the transducer and circuit quantum electrodynamics system enable complete isolation of the qubit from optical photons, with minimal backaction on the qubit. Improvements in the transducer bandwidth and noise levels will enable the transduction of non-classical signals from a superconducting qubit to the optical domain.
Article
Physics, Multidisciplinary
Luca Chirolli, Norman Y. Yao, Joel E. Moore
Summary: The hybrid architecture proposed in this Letter combines a superconducting qubit with a topologically protected Majorana memory, enabling the combination of fast gates and long-lived quantum memories.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Matthew Ware, Guilhem Ribeill, Diego Riste, Colm A. Ryan, Blake Johnson, Marcus P. da Silva
Summary: This study demonstrates the implementation of Pauli-frame randomization in a superconducting circuit system to shape noise into more benign forms for quantum error correction and fault tolerance. By randomizing circuits, signatures of non-Markovian evolution are suppressed to statistically insignificant levels, while maintaining fidelity and even improving error rates. The randomization technique ensures rigorous statements about error properties and contributes to the scalability of quantum computing with imperfect qubits.
Article
Physics, Multidisciplinary
Weijian Chen, Maryam Abbasi, Byung Ha, Serra Erdamar, Yogesh N. Joglekar, Kater W. Murch
Summary: We observe exceptional points of the Liouvillian superoperator in open quantum systems interacting with an environment, which are associated with critical dynamics as the system approaches steady state. By dynamically tuning the Liouvillian superoperators in real time, we achieve nonHermiticity-induced chiral state transfer.
PHYSICAL REVIEW LETTERS
(2022)
Article
Engineering, Multidisciplinary
M. R. Pourkarimi, S. Haddadi, M. Nashaat, K. V. Kulikov, Yu. M. Shukrinov
Summary: This paper investigates the thermal evolution of a two-qubit superconducting system by considering the local quantum uncertainty (LQU) as a measure of quantum correlations. It is shown that the thermal LQU can be increased by manipulating the Hamiltonian parameters, but undergoes sudden transitions at specific temperatures. Furthermore, the impact of decohering channels on thermal LQU is analyzed.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Physics, Multidisciplinary
Brennan Undseth, Oriol Pietx-Casas, Eline Raymenants, Mohammad Mehmandoost, Mateusz T. Madzik, Stephan G. J. Philips, Sander L. de Snoo, David J. Michalak, Sergey V. Amitonov, Larysa Tryputen, Brian Paquelet Wuetz, Viviana Fezzi, Davide Degli Esposti, Amir Sammak, Giordano Scappucci, Lieven M. K. Vandersypen
Summary: As spin-based quantum processors grow in size and complexity, maintaining high fidelities and minimizing crosstalk are crucial for successful quantum algorithms and error-correction protocols. This study makes significant progress in understanding and overcoming the detrimental effects of microwave qubit driving on qubit frequency shifts. Operating the device at 200 mK effectively suppresses adverse heating effects without compromising qubit coherence or fidelity benchmarks. Furthermore, systematic non-Markovian crosstalk is greatly reduced.
Article
Physics, Applied
Wei Feng, Guo-Qiang Zhang, Qi-Ping Su, Jun-Xiang Zhang, Chui-Ping Yang
Summary: The researchers propose a protocol to generate Greenberger-Horne-Zeilinger (GHZ) states on 2D superconducting-qubit lattices by applying multiqubit controlled-iSWAP gates in parallel. They simulate the preparation process with realistic parameters and show that a 37-qubit GHZ state can be generated using a controlled-iSWAP depth of 3. This method provides a more promising way to generate GHZ states on the latest 2D superconducting-qubit architectures.
PHYSICAL REVIEW APPLIED
(2022)
Article
Materials Science, Multidisciplinary
M. Pejic, Z. Przulj, D. Chevizovich, N. Lazarides, G. P. Tsironis, Z. Ivic
Summary: We study the quantum features of electromagnetic radiation in a one-dimensional superconducting quantum metamaterial and find the emergence of bound states of single-photon qubits. This discovery indicates the potential application of controlling photon transport in artificial media based on superconducting qubits.
Article
Quantum Science & Technology
Jonginn Yun, Jaemin Park, Hyeongyu Jang, Jehyun Kim, Wonjin Jang, Younguk Song, Min-Kyun Cho, Hanseo Sohn, Hwanchul Jung, Vladimir Umansky, Dohun Kim
Summary: We demonstrate the simultaneous operation and measurement of two-electron spin qubits, decoupled from nuclear noise, in a GaAs quadruple quantum dot array. Coherent Rabi oscillations of both qubits are achieved by tuning their drive frequency using real-time Hamiltonian estimators. Strong two-qubit capacitive interaction and state-conditional frequency shift are observed, consistent with theoretical predictions. The high coherence to conditional phase-flip time ratio suggests the potential for generating high-fidelity and fast quantum entanglement using a simple capacitive interaction.
NPJ QUANTUM INFORMATION
(2023)
Article
Optics
Wei Li, Likang Zhang, Hao Tan, Yichen Lu, Sheng-Kai Liao, Jia Huang, Hao Li, Zhen Wang, Hao-Kun Mao, Bingze Yan, Qiong Li, Yang Liu, Qiang Zhang, Cheng-Zhi Peng, Lixing You, Feihu Xu, Jian-Wei Pan
Summary: This article reports a QKD system that can generate keys at a record high rate of 115.8 Mb/s over a 10 km standard optical fiber and distribute keys over up to 328 km of ultralow-loss fiber. These abilities are attributed to a multipixel superconducting nanowire single-photon detector with an ultrahigh counting rate, an integrated transmitter that can stably encode polarization states with low error, a fast post-processing algorithm for generating keys in real time, and the high system clock rate operation. The results demonstrate the feasibility of practical high-rate QKD with photonic techniques, thus opening its possibility for widespread applications.
Article
Physics, Multidisciplinary
Wei Li, Likang Zhang, Yichen Lu, Zheng-Ping Li, Cong Jiang, Yang Liu, Jia Huang, Hao Li, Zhen Wang, Xiang-Bin Wang, Qiang Zhang, Lixing You, Feihu Xu, Jian-Wei Pan
Summary: We propose and demonstrate a new method to achieve twin-field quantum key distribution (TF-QKD) without the need for phase locking. By separating the communication time into reference frames and quantum frames, we establish a global phase reference using the reference frames and reconcile the phase reference efficiently using a tailored algorithm based on fast Fourier transform. We successfully demonstrate no-phase-locking TF-QKD from short to long distances over standard optical fibers, achieving high secret key rates and repeaterlike key rates. Our work provides a scalable and practical solution to TF-QKD, representing an important step towards its wide applications.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Jian Qin, Yu-Hao Deng, Han-Sen Zhong, Li-Chao Peng, Hao Su, Yi-Han Luo, Jia-Min Xu, Dian Wu, Si-Qiu Gong, Hua-Liang Liu, Hui Wang, Ming-Cheng Chen, Li Li, Nai-Le Liu, Chao-Yang Lu, Jian-Wei Pan
Summary: Quantum metrology aims to enhance measurement sensitivity by utilizing quantum resources. We propose and realize a novel quantum metrology scheme that combines unconventional nonlinear interferometers and stimulated emission of squeezed light. Our method achieves a scalable, unconditional, and robust quantum metrological advantage, outperforming ideal 5-N00N states. The demonstrated enhancement in Fisher information per photon, without discounting for imperfections or photon loss, makes our approach applicable in practical quantum metrology at low photon flux regime.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Xue-Mei Gu, Liang Huang, Alejandro Pozas-Kerstjens, Yang-Fan Jiang, Dian Wu, Bing Bai, Qi-Chao Sun, Ming-Cheng Chen, Jun Zhang, Sixia Yu, Qiang Zhang, Chao-Yang Lu, Jian-Wei Pan
Summary: Nonlocality in networks composed of independent sources exhibits different phenomena compared to standard Bell scenarios. Network nonlocality in the entanglement-swapping scenario has been extensively studied, but previous violations of bilocality inequality could not certify the nonclassicality of their sources. We experimentally observe full network nonlocal correlations in a network where the loopholes of source-independence, locality, and measurement-independence are closed. Our experiment violates known inequalities for nonfull network nonlocal correlations by over 5 standard deviations, confirming the absence of classical sources.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Li-Zheng Liu, Yue-Yang Fei, Yingqiu Mao, Yi Hu, Rui Zhang, Xu-Fei Yin, Xiao Jiang, Li Li, Nai-Le Liu, Feihu Xu, Yu-Ao Chen, Jian-Wei Pan
Summary: In this study, a full-period quantum phase estimation approach is proposed and demonstrated. The approach adopts Kitaev's phase estimation algorithm to eliminate phase ambiguity and uses GHZ states to obtain phase values. Through an eight-photon experiment, the estimation of unknown phases in a full period is achieved, and the phase super-resolution and sensitivity beyond the shot-noise limit are observed. This research provides a new way for quantum sensing and represents a solid step towards its general applications.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Chong Ying, Bin Cheng, Youwei Zhao, He-Liang Huang, Yu-Ning Zhang, Ming Gong, Yulin Wu, Shiyu Wang, Futian Liang, Jin Lin, Yu Xu, Hui Deng, Hao Rong, Cheng-Zhi Peng, Man -Hong Yung, Xiaobo Zhu, Jian-Wei Pan
Summary: Although NISQ quantum computing devices are still limited in terms of qubit quantity and quality, quantum computational advantage has been experimentally demonstrated. Hybrid quantum and classical computing architectures have become the main paradigm for exhibiting NISQ applications, with the use of low-depth quantum circuits. This study demonstrates a circuit-cutting method for simulating quantum circuits with multiple logical qubits using only a few physical superconducting qubits, showcasing higher fidelity and scalability.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Yu-Hao Deng, Si-Qiu Gong, Yi-Chao Gu, Zhi-Jiong Zhang, Hua-Liang Liu, Hao Su, Hao-Yang Tang, Jia-Min Xu, Meng-Hao Jia, Ming-Cheng Chen, Han-Sen Zhong, Hui Wang, Jiarong Yan, Yi Hu, Jia Huang, Wei -Jun Zhang, Hao Li, Xiao Jiang, Lixing You, Zhen Wang, Li Li, Nai-Le Liu, Chao -Yang Lu, Jian-Wei Pan
Summary: Gaussian boson sampling (GBS) is a protocol for demonstrating quantum computational advantage and is mathematically associated with graph-related and quantum chemistry problems. This study investigates the enhancement of GBS over classical stochastic algorithms on noisy quantum devices in the computationally interesting regime. Experimental results show the presence of GBS enhancement with a large photon-click number and robustness under certain noise, which may stimulate the development of more efficient classical and quantum-inspired algorithms.
PHYSICAL REVIEW LETTERS
(2023)
Article
Instruments & Instrumentation
Chao Yu, Tianyi Li, Xian-Song Zhao, Hai Lu, Rong Zhang, Feihu Xu, Jun Zhang, Jian-Wei Pan
Summary: In this study, a 4H-SiC single-photon avalanche diode (SPAD) based free-running ultraviolet single-photon detector (UVSPD) with ultralow afterpulse probability is reported. A beveled mesa structure is designed and fabricated for the 4H-SiC SPAD, which shows the characteristic of ultralow dark current. A readout circuit of passive quenching and active reset with a tunable hold-off time setting is further developed to significantly suppress the afterpulsing effect. The nonuniformity of photon detection efficiency (PDE) across the SPAD active area is investigated for performance optimization. The compact UVSPD shows a PDE of 10.3%, a dark count rate of 133 kcps, and an afterpulse probability of 0.3% at 266 nm, indicating its potential for practical ultraviolet photon-counting applications.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Quantum Science & Technology
Chen Ding, Xiao-Yue Xu, Yun-Fei Niu, Shuo Zhang, He-Liang Huang, Wan-Su Bao
Summary: To reduce labeling and computational costs in quantum machine learning, the active learning (AL) strategy is used to select a subset of the dataset for training while maintaining performance. Two AL-inspired variational quantum classifiers were designed and implemented to investigate the potential applications and effectiveness of AL in quantum machine learning. The results demonstrate the significant advantage of AL in saving labeling efforts and computational resources.
QUANTUM SCIENCE AND TECHNOLOGY
(2023)
Article
Quantum Science & Technology
Hsin-Pin Lo, Takuya Ikuta, Koji Azuma, Toshimori Honjo, William J. Munro, Hiroki Takesue
Summary: In this study, a three-photon time-bin Greenberger-Horne-Zeilinger (GHZ) state is generated using a 2 x 2 optical switch as a time-dependent beam splitter. The state is created by entangling time-bin Bell states from a spontaneous parametric down-conversion source and a weak coherent pulse. The characterization of the state is done through measurement estimation, violation of the Mermin inequality, and quantum state tomography, showing a state fidelity exceeding 70%. The three-photon time-bin GHZ state has potential applications in long-distance multi-user quantum communication.
QUANTUM SCIENCE AND TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Sirui Cao, Bujiao Wu, Fusheng Chen, Ming Gong, Yulin Wu, Yangsen Ye, Chen Zha, Haoran Qian, Chong Ying, Shaojun Guo, Qingling Zhu, He-Liang Huang, Youwei Zhao, Shaowei Li, Shiyu Wang, Jiale Yu, Daojin Fan, Dachao Wu, Hong Su, Hui Deng, Hao Rong, Yuan Li, Kaili Zhang, Tung-Hsun Chung, Futian Liang, Jin Lin, Yu Xu, Lihua Sun, Cheng Guo, Na Li, Yong-Heng Huo, Cheng-Zhi Peng, Chao-Yang Lu, Xiao Yuan, Xiaobo Zhu, Jian-Wei Pan
Summary: Scalable generation of genuine multipartite entanglement on a large-scale quantum device is demonstrated. High-fidelity parallel quantum gates are used to prepare and verify intermediate-scale genuine entanglement on a 66-qubit superconducting quantum processor. The approach enables medium-scale quantum computing with superconducting quantum systems.
Article
Physics, Multidisciplinary
Guo-Xian Su, Hui Sun, Ana Hudomal, Jean-Yves Desaules, Zhao-Yu Zhou, Bing Yang, Jad C. Halimeh, Zhen-Sheng Yuan, Zlatko Papie, Jian-Wei Pan
Summary: The ongoing quest for understanding nonequilibrium dynamics of complex quantum systems has led to the discovery of quantum many-body scarring. This phenomenon allows for the delay of thermalization by preparing the system in special initial states. In this study, the researchers demonstrate many-body scarring in a Bose-Hubbard quantum simulator, using previously unknown initial conditions. This work opens up new possibilities for exploring the relationship between scarring and various quantum phenomena.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Optics
Hiroo Azuma, William J. Munro, Kae Nemoto
Summary: We investigate the Leggett-Garg inequalities (LGIs) in a boson system by deforming the Pegg-Barnett phase operators. The quantum Fourier transform is used for the required measurements. The explicit forms of the LGIs are derived using the coherent state |alpha) as the initial state, and the violation of LGIs is explored with varying time difference between observations of the phase operators. The nonclassicality of the system remains in the large amplitude limit without dissipation, but diminishes rapidly with dissipation.
Article
Optics
Jin Cao, Huan Yang, Zhen Su, Xin-Yao Wang, Jun Rui, Bo Zhao, Jian-Wei Pan
Summary: We have successfully prepared a quantum degenerate mixture of 23Na 40K molecules and 40K atoms. The atoms are highly degenerate with a large number ratio, while the molecules are in a moderately degenerate state. The elastic collisions between the atoms and molecules provide a thermalization mechanism, allowing the molecules to reach thermal equilibrium before significant losses occur. The degeneracy of the molecules is maintained for a sufficient time interval for further study and production of ultracold triatomic molecular gases.
Article
Optics
Aoi Hayashi, Akitada Sakurai, Shin Nishio, William J. Munro, Kae Nemoto
Summary: The quantum extreme reservoir computation (QERC) is a versatile quantum neural network model that addresses the optimization problem of different instances by generating complex quantum reservoirs. In this research, a periodically driven system Hamiltonian dynamics is used as the quantum feature map and characterized and evaluated by weighted networks. Additionally, a simple Hamiltonian model based on a disordered discrete time crystal achieves near-optimal performance without the need for gate-by-gate programming of the quantum processor.
