Article
Optics
Shaoping Shi, Yajun Wang, Long Tian, Wei Li, Yimiao Wu, Qingwei Wang, Yaohui Zheng, Kunchi Peng
Summary: This article presents a fully connected continuous-variable quantum teleportation network architecture, where a squeezed state of light distributes entangled sideband modes to each communication link, offering potential for various tasks of quantum information processing.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Liang Wu, Ting Chai, Yanhong Liu, Yaoyao Zhou, Jiliang Qin, Zhihui Yan, Xiaojun Jia
Summary: This article proposes a feasible scheme to distribute quadripartite entanglement using continuous-variable polarization states, enabling long-distance entanglement distribution in commercial optical fiber communication networks. Different types of polarization entangled states can be distributed by controlling the beam splitter network in the quantum server. The protocol provides important references for experimental implementation and metropolitan quantum networks.
Article
Optics
Federico Centrone, Frederic Grosshans, Valentina Parigi
Summary: We studied continuous-variable graph states with regular and complex network shapes, and analyzed the relationship between the cost, the number of squeezed modes, and the topology. We provided an analytical formula to compute the experimental resources needed, and showed that increasing homodyne measurements can boost entanglement and enhance the efficiency of entanglement routing protocol.
Article
Quantum Science & Technology
Deepak, Arpita Chatterjee
Summary: We investigate continuous-variable quantum teleportation protocols using entangled displaced Fock states. It is found that displaced Fock states do not have an advantage in teleporting squeezed and coherent states. We also discuss the effects of decoherence on teleportation.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Multidisciplinary Sciences
Mingjian He, Robert Malaney
Summary: In this study, a new CV-based teleportation protocol is explored to improve the transfer of hybrid entangled states. The modified protocol shows significant improvement over traditional CV teleportation for both DV qubits and CV qubits. Additionally, the use of non-Gaussian operations with quantum scissors provides the most improvement in loss tolerance.
SCIENTIFIC REPORTS
(2022)
Article
Optics
Y. U. E. Qin, J. I. N. G. X. U. Ma, J. I. A. L. I. N. Cheng, Z. H. I. H. U. I. Yan, X. I. A. O. J. U. N. Jia
Summary: Quantum conference (QC) is a cryptographic task for secure communications among multiple users. The Greenberger-Horne-Zeilinger (GHZ) entangled state is used as the basic resource, and a continuous variable (CV) GHZ entangled state allows the establishment of an unconditional and efficient quantum network. An implementation of QC scheme using a CV multipartite GHZ entangled state is reported, where submodes of a quadripartite GHZ entangled state are distributed to four spatially separated users. The proposed QC scheme is secure against lossy quantum channels and collective Gaussian attacks.
PHOTONICS RESEARCH
(2023)
Article
Optics
Hui Guo, Na Liu, Zhi LI, Rongguo Yang, Hengxin Sun, Kui Liu, Jiangrui Gao
Summary: This study reports the generation of continuous-variable high-dimensional entanglement using a single OPO cavity and verifies its entanglement in terms of frequency, spin, and orbital angular momentum. Furthermore, the advantages of high-dimensional entanglement in quantum communication and its potential applications in quantum protocols, quantum imaging, and quantum computing are demonstrated.
PHOTONICS RESEARCH
(2022)
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
Materials Science, Multidisciplinary
Wei Zhao, Fu-qiang Wang, Yi-yu Mao, Hai Zhong, Chao Ding, Xin-chao Ruan
Summary: In this paper, a continuous-variable quantum digital signature protocol based on quantum teleportation is proposed and analyzed. Squeezed states are used to carry key and secret information of the teleported states transmitted through classical and entangled channels. The mean and modulation variance of the teleported quantum state are used to distinguish and order multibit information signatures. The fidelity and security analysis demonstrate the effectiveness and security of the proposed protocol.
RESULTS IN PHYSICS
(2023)
Article
Quantum Science & Technology
Masashi Ban
Summary: The study focuses on continuous variable teleportation with indefinite causal order in an optical system, deriving the relationship between input and teleported states, and evaluating performance in terms of fidelity. Analysis of teleportation of different states demonstrates that indefinite causal order can enhance fidelity in continuous variable teleportation.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Optics
Ayan Patra, Rivu Gupta, Saptarshi Roy, Aditi Sen(De)
Summary: In this study, the concept of fidelity deviation is introduced in continuous-variable quantum teleportation, allowing better characterization of CV states by considering both fidelity and fidelity deviation. The performance of the teleportation protocol is also explored in different input scenarios, and the effects of noise on average fidelity and fidelity deviation are investigated.
Article
Optics
Qingwei Wang, Yajun Wang, Xiaocong Sun, Yuhang Tian, Wei Li, Long Tian, Xudong Yu, Jing Zhang, Yaohui Zheng
Summary: A universal scheme of a continuous variable quantum state distributor that performs point-to-multipoint distributions via quantum teleportation with partially disembodied transport is presented. Controllable distributions were demonstrated by manipulating the squeezing factor of EPR entanglement, leading to gradual changes in the fidelities of the receivers.
Article
Optics
Hui Guo, Na Liu, Hengxin Sun, Kui Liu, Jiangrui Gao
Summary: Optical spin-orbit coupling is investigated in the optical parametric downconversion process, and entangled vector vortex modes are experimentally generated. The spin-orbit quantum states are characterized on the quantum higher-order Poincare sphere, and the relationship of spin-orbit total angular momentum Stokes entanglement is demonstrated. These states have potential applications in high-dimensional quantum communication and multiparameter measurement.
Article
Optics
Hemant K. Mishra, Samad Khabbazi Oskouei, Mark M. Wilde
Summary: In this paper, an analytical approach for determining optimal input states for continuous-variable (CV) unidirectional and bidirectional teleportation is detailed. The metric used to quantify performance is the energy-constrained channel fidelity between ideal and experimental teleportation. The paper proves that, under certain energy constraints, the optimal input state is a finite entangled superposition of twin-Fock states, and it is unique.
Article
Optics
Ludovico Lami
Summary: This paper investigates data hiding in continuous-variable quantum systems, analyzing the efficiency limits of data hiding under measurements implementable with local operations and classical communication, as well as data hiding against Gaussian operations assisted by measurement outcomes feedback. By performing a quantitative analysis of errors introduced by quantum teleportation protocol, the required squeezing and local detection efficiency for teleporting arbitrary multimode local states with known mean energy is determined.
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
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
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
Viktor Nordgren, Olga Leskovjanova, Jan Provaznik, Adam Johnston, Natalia Korolkova, Ladislav Mista
Summary: This paper investigates genuine multipartite entanglement in Gaussian states and proposes a method to verify this entanglement solely from separable two-mode marginals. Examples of Gaussian states carrying genuine multipartite entanglement are constructed, and an experimental scheme for preparing the simplest three-mode state is proposed. These results not only reveal a new concept of entanglement in the Gaussian scenario, but also pave the way for effective diagnostics methods of global properties of multipartite states.
Article
Optics
Ladislav Mista, Hubert de Guise, Jaroslav Rehacek, Zdenek Hradil
Summary: This study establishes a full quantum analogy between angular momentum and exponential angular variable, as well as the structure of canonically conjugate position and momentum. It introduces the concept of optimal simultaneous measurement, Einstein-Podolsky-Rosen-like variables and states, and a phase-space representation of quantum states. The research is significant for the implementation of quantum technologies combining discrete and continuous quantum variables.
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
Physics, Multidisciplinary
Shunya Konno, Warit Asavanant, Kosuke Fukui, Atsushi Sakaguchi, Fumiya Hanamura, Petr Marek, Radim Filip, Jun-ichi Yoshikawa, Akira Furusawa
Summary: This paper explores the method of implementing non-Clifford operations on GKP qubits, achieving high-fidelity linear optical implementation by combining nonlinear feedforward and GKP-encoded ancillary states.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Quantum Science & Technology
Ryan Amiri, Robert Starek, David Reichmuth, Ittoop Puthoor, Michal Micuda, Ladislav Mista, Miloslav Dusek, Petros Wallden, Erika Andersson
Summary: Oblivious transfer is a crucial primitive in modern cryptography with various applications, including secure multiparty computation and e-voting. While achieving information-theoretically secure perfect 1-out-of-2 oblivious transfer is impossible, imperfect variants using quantum means are feasible. The introduced theoretical framework for studying semirandom quantum oblivious transfer provides insights into cheating probabilities and bounds on security. The proposed protocol with reduced cheating probabilities compared to existing schemes can be implemented optically and does not require entangled states, showcasing promising advancements in the field.
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.