Article
Physics, Multidisciplinary
Bartosz Regula, Ludovico Lami, Giovanni Ferrari, Ryuji Takagi
Summary: The study introduces a general method for quantifying resources for continuous-variable quantum systems based on robustness measure, with a direct operational interpretation. It is shown to be a well-behaved resource quantifier applicable to various physically relevant resources, such as optical nonclassicality.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Stefano Bosco, Pasquale Scarlino, Jelena Klinovaja, Daniel Loss
Summary: Spin qubits in silicon and germanium quantum dots are promising platforms for quantum computing. However, there is a critical challenge of entangling spin qubits over micrometer distances. Current research focuses on maximizing interactions between qubits and microwave resonators, but this leads to unavoidable residual qubit-qubit couplings. Interestingly, these residual couplings can be eliminated by introducing longitudinal spin-photon interactions in hole spin qubits.
PHYSICAL REVIEW LETTERS
(2022)
Article
Quantum Science & Technology
Timjan Kalajdzievski, Nicolas Quesada
Summary: Exact decomposition methods have lower gate counts, while approximate techniques cover decompositions for all operations but require significant circuit depth.
Article
Physics, Multidisciplinary
Vladyslav C. Usenko
Summary: This study focuses on minimizing information leakage from continuous-variable quantum channels, investigating the conditions for minimum leakage under individual attacks and analyzing the properties of mutual information quantities. The research reveals that joint measurements on modes may not always be more effective than independent measurements, and varying signal variance can lead to nontrivial statistical effects.
Article
Quantum Science & Technology
Robert I. Booth, Damian Markham
Summary: In measurement-based quantum computing, the concept of CV-flow is introduced for continuous-variable graph states. It approximates a unitary transformation well and addresses convergence issues in the infinite-dimensional setting. Additionally, a method for converting CV-MBQC computation into circuit form is provided.
Article
Quantum Science & Technology
Daoheng Niu, Yuxuan Zhang, Alireza Shabani, Hassan Shapourian
Summary: This paper proposes a general framework for all-photonic one-way quantum repeaters based on measurement-based error correction, which can be adapted to various quantum codes and effectively reduces resource utilization.
NPJ QUANTUM INFORMATION
(2023)
Article
Optics
Qingwei Wang, Wei Li, Yimiao Wu, Wenxiu Yao, Fan Li, Long Tian, Yajun Wang, Yaohui Zheng
Summary: The experiment demonstrates unconditional 1 -> 3 quantum telecloning of coherent states, with fidelities of the cloned states at 0.64 +/- 0.01, 0.64 +/- 0.01, and 0.49 +/- 0.01, respectively. The use of quadripartite entangled modes as an auxiliary resource ensures that no information about the unknown state is lost during the telecloning process. Deterministic 1 -> 3 quantum telecloning shows great potential for applications in advanced quantum technology.
Article
Physics, Multidisciplinary
Xue-Jian Sun, Wen-Xiao Liu, Hao Chen, Cheng-Yuan Wang, Hui-Zhong Ma, Hong-Rong Li
Summary: In this work, a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond is proposed. By using a continuous dynamical decoupling approach and a mechanical driving field, the influence of spin decoherence on the gate is suppressed and the gate fidelity is significantly improved.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Quantum Science & Technology
Carlos Gonzalez-Arciniegas, Paulo Nussenzveig, Marcelo Martinelli, Olivier Pfister
Summary: Continuous-variable (CV) cluster states, achieved through quantum optics, have surpassed qubit platforms in terms of scalability, with fault tolerance thresholds reachable at realistic squeezing levels. However, standard approaches may overlook hidden entanglement in the system, which can potentially enhance the power of a quantum computer.
Article
Computer Science, Software Engineering
Tianyu Wang, Jiong Chen, Dongping Li, Xiaowei Liu, Huamin Wang, Kun Zhou
Summary: This article proposes a novel two-way method for fast and reliable continuous collision handling. The method optimizes a path from the time-integrated state to the intersection-free state, providing flexible and reliable handling of deformable bodies.
ACM TRANSACTIONS ON GRAPHICS
(2023)
Article
Quantum Science & Technology
Stefano Bosco, Bence Hetenyi, Daniel Loss
Summary: Hole Si fin field-effect transistors (FinFETs) are shown to be highly compatible with modern CMOS technology and have operational sweet spots where charge noise is completely removed. The presence of these sweet spots is a result of the interplay between material anisotropy and the shape of the FinFET cross section. Designs that maximize qubit performance and potentially pave the way towards a scalable spin-based quantum computer are identified.
Article
Multidisciplinary Sciences
Jan Provaznik, Radim Filip, Petr Marek
Summary: Numerical simulation of continuous variable quantum state preparation is essential for optimizing quantum information processing protocols. This study presents a powerful tool for such simulations using Fock state representation and numerical computation. The accuracy of several methods for computing the truncated coherent displacement operator is analyzed in an approximation of the infinite-dimensional Fock space by finite complex vector spaces. An alternative method with improved accuracy, based on the standard matrix exponential, is proposed. The method is then applied to analyze non-Gaussian state preparation schemes using coherent displacement of a two mode squeezed vacuum and photon counting measurement. Different detection mechanisms, including avalanche photodiodes, their cascades, and photon number resolving detectors, are compared for engineering non-linearly squeezed cubic states and constructing qubit-like superpositions.
SCIENTIFIC REPORTS
(2022)
Article
Multidisciplinary Sciences
Matteo Lodi, Francesco Sorrentino, Marco Storace
Summary: In networks of coupled oscillators, clusters of nodes in directed networks may exhibit one-way dependencies, where the synchronization of one cluster depends on the stability of another. A method to transform the cluster stability problem in an irreducible form is proposed, allowing for the detection of inter-dependencies among clusters. The mechanisms of cluster formation in networks with directed links differ from those in undirected networks.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
Johannes Nokkala, Rodrigo Martinez-Pena, Gian Luca Giorgi, Valentina Parigi, Miguel C. Soriano, Roberta Zambrini
Summary: The study demonstrates that linear systems with continuous-variable Gaussian states can serve as a promising platform for quantum reservoir computing with universal approximation capabilities. Encoding the input into Gaussian states serves both as a source and a means to tune the nonlinearity of the overall input-output map. By encoding to quantum fluctuations, such as squeezed vacuum, instead of classical fields or thermal fluctuations, the full potential of the proposed model can be reached.
COMMUNICATIONS PHYSICS
(2021)
Article
Quantum Science & Technology
Kah Jen Wo, Guus Avis, Filip Rozpedek, Maria Flors Mor-Ruiz, Gregor Pieplow, Tim Schroeder, Liang Jiang, Anders S. Sorensen, Johannes Borregaard
Summary: This study proposes a resource-efficient one-way quantum repeater that utilizes quantum error-correcting codes to counteract loss and operational error rates in a communication channel. By minimizing resource overhead and using tailored error-correcting codes, reliable quantum bit transmission can be achieved over intercontinental distances.
NPJ QUANTUM INFORMATION
(2023)
Article
Physics, Applied
Shunya Konno, Atsushi Sakaguchi, Warit Asavanant, Hisashi Ogawa, Masaya Kobayashi, Petr Marek, Radim Filip, Jun-ichi Yoshikawa, Akira Furusawa
Summary: In this paper, a superposition between a vacuum state and a single-photon state with maximized nonlinear squeezing is generated and observed in real-time quadrature measurements. This work presents an important step in extending continuous-variable quantum information processing from the Gaussian regime to the non-Gaussian regime.
PHYSICAL REVIEW APPLIED
(2021)
Correction
Engineering, Electrical & Electronic
Naoto Takanashi, Takahiro Kashiwazaki, Takushi Kazama, Koji Enbutsu, Ryoichi Kasahara, Takeshi Umeki, Akira Furusawa
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2021)
Article
Computer Science, Information Systems
Yuanlong Wang, Shota Yokoyama, Daoyi Dong, Ian R. Petersen, Elanor H. Huntington, Hidehiro Yonezawa
Summary: Quantum detector tomography is a fundamental technique for calibrating quantum devices and performing quantum engineering tasks. In this paper, a novel quantum detector tomography method is proposed. The Two-stage Estimation method has computational complexity O(nd(2)M) and is validated through simulation and a quantum optical experiment.
IEEE TRANSACTIONS ON INFORMATION THEORY
(2021)
Article
Physics, Applied
Warit Asavanant, Baramee Charoensombutamon, Shota Yokoyama, Takeru Ebihara, Tomohiro Nakamura, Rafael N. Alexander, Mamoru Endo, Jun-ichi Yoshikawa, Nicolas C. Menicucci, Hidehiro Yonezawa, Akira Furusawa
Summary: Recent progress in continuous-variable optical quantum computation has seen the realization of scalable measurement bases using cluster states through time-domain multiplexing. Demonstrations of quantum operations using time-domain-multiplexed cluster states have been successful, with a proposed method to evaluate and verify continuous-variable operations. These advancements bring the realization of large-scale fault-tolerant universal optical quantum computers closer to reality.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Applied
Takahiro Kashiwazaki, Taichi Yamashima, Naoto Takanashi, Asuka Inoue, Takeshi Umeki, Akira Furusawa
Summary: A low-loss quasi-single-mode periodically poled LiNbO3 (PPLN) waveguide was fabricated using mechanical polishing processes, which allowed for larger squeezing level. This waveguide was utilized to assemble a low-loss fiber-pigtailed OPA module, showing promising results for high-speed large-scale fault-tolerant quantum computing. The waveguide did not exhibit pump-induced optical loss even under high power pumping conditions.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Multidisciplinary
Kosuke Fukui, Shuntaro Takeda, Mamoru Endo, Warit Asavanant, Jun-ichi Yoshikawa, Peter van Loock, Akira Furusawa
Summary: Non-Gaussian states are crucial for optical quantum technologies, and the optical quantum state synthesizer (OQSS) is a promising method for their preparation. However, the complexity of simulating state preparation on a classical computer poses a significant challenge. To overcome this, we propose a backcasting approach and show that the requirements for photon-number resolving detectors can be significantly reduced.
PHYSICAL REVIEW LETTERS
(2022)
Article
Automation & Control Systems
Yanan Liu, Daoyi Dong, Ian R. Petersen, Qing Gao, Steven X. Ding, Shota Yokoyama, Hidehiro Yonezawa
Summary: This article aims to design a coherent feedback controller for a class of linear quantum systems suffering from Markovian jumping faults, to achieve fault tolerance and H-infinity disturbance attenuation performance. An H-infinity controller is designed by solving a set of linear matrix inequalities, and a real application to quantum optical systems is proposed.
IEEE TRANSACTIONS ON AUTOMATIC CONTROL
(2022)
Article
Physics, Applied
A. Inoue, T. Kashiwazaki, T. Yamashima, N. Takanashi, T. Kazama, K. Enbutsu, K. Watanabe, T. Umeki, M. Endo, A. Furusawa
Summary: In this work, a real-time amplitude measurement method for continuous-variable optical quantum information processing is developed using a modular optical parametric amplifier (OPA) and a broadband balanced photodiode. This method improves the clock frequency limitation of homodyne detectors and enables the realization of high clock frequency optical quantum computers and multi-core systems.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Takahiro Kashiwazaki, Taichi Yamashima, Koji Enbutsu, Takushi Kazama, Asuka Inoue, Kosuke Fukui, Mamoru Endo, Takeshi Umeki, Akira Furusawa
Summary: We achieved continuous-wave 8.3 dB squeezed light generation using a terahertz-order-broadband waveguide optical parametric amplifier through improvements in the measurement setup. By reducing optical loss and minimizing phase-locking fluctuations, we were able to optimize the experimental parameters for squeezing levels. This highly squeezed light without loss-correction and circuit-noise correction holds promise for fault-tolerant ultra-fast optical quantum computers.
APPLIED PHYSICS LETTERS
(2023)
Article
Quantum Science & Technology
Kan Takase, Kosuke Fukui, Akito Kawasaki, Warit Asavanant, Mamoru Endo, Jun-ichi Yoshikawa, Peter van Loock, Akira Furusawa
Summary: This article proposes a synthesizer that encodes Gottesman-Kitaev-Preskill (GKP) qubits in propagating light by exploiting the nonlinearity of photon detectors. The synthesizer offers several advantages, including systematic and rigorous synthesis of arbitrary GKP qubits, minimal resource usage, high fidelity and success probability, and robustness against loss.
NPJ QUANTUM INFORMATION
(2023)
Article
Optics
Warit Asavanant, Kosuke Fukui, Atsushi Sakaguchi, Akira Furusawa
Summary: This paper presents an optical quantum computation platform that does not require optical switches. Instead, it is based on continuous-variable measurement-based quantum computation, where the quantum entanglement structure is modified to allow quantum teleportation to replace optical switching and rerouting. The architecture also includes additional modes that enable the teleportation of quantum states along the cluster state, a task typically requiring optical switches.
Article
Optics
Kosuke Fukui, Mamoru Endo, Warit Asavanant, Atsushi Sakaguchi, Jun-ichi Yoshikawa, Akira Furusawa
Summary: This article introduces a method to generate optical GKP qubits using cross-Kerr interaction and validates its feasibility through numerical calculations. The results show that the method is capable of generating GKP qubits with the required quality, achieving high fidelity and success probability.
Article
Optics
Fumiya Hanamura, Warit Asavanant, Kosuke Fukui, Shunya Konno, Akira Furusawa
Summary: This study focuses on the estimation and error correction of displacements in continuous-variable quantum information processing using non-Gaussian states. Analysis of complex GKP states and experimentally feasible single-photon states reveals the importance of non-Gaussianity for displacement estimation, demonstrating that non-Gaussian states can surpass the lower bound achieved with Gaussian operations.
Article
Optics
Warit Asavanant, Kan Takase, Kosuke Fukui, Mamoru Endo, Jun-ichi Yoshikawa, Akira Furusawa
Summary: The study introduces a new method to tailor the wave functions of quantum states using non-Gaussian entangled states, allowing for the generation of various classes of quantum states. The results highlight the importance of conditioning using homodyne measurements in complement to photon number detection for generating non-Gaussian states.
Article
Optics
Kan Takase, Jun-ichi Yoshikawa, Warit Asavanant, Mamoru Endo, Akira Furusawa
Summary: We propose a high-rate generation method of optical Schrodinger cat states by photon number measurement in one mode of two-mode Gaussian states, which relaxes constraints on experimental parameters and allows for a high generation rate. This method can potentially exceed conventional photon subtraction rates by about 103 to 106 times, making it important for quantum computing applications.
