1
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Lund MM, Yang F, Christiansen VR, Kornovan D, Mølmer K. Subtraction and Addition of Propagating Photons by Two-Level Emitters. PHYSICAL REVIEW LETTERS 2024; 133:103601. [PMID: 39303266 DOI: 10.1103/physrevlett.133.103601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 07/29/2024] [Indexed: 09/22/2024]
Abstract
Coherent manipulation of quantum states of light is key to photonic quantum information processing. In this Letter, we show that a passive two-level nonlinearity suffices to implement non-Gaussian quantum operations on propagating field modes. In particular, the collective light-matter interaction can efficiently extract a single photon from a multiphoton input wave packet to an orthogonal temporal mode. We accurately describe the single-photon subtraction process by elements of an intuitive quantum-trajectory model. By employing this process, quantum information protocols gain orders of magnitude improved efficiency over heralded schemes with linear optics. The reverse process can be used to add photons one by one to a single wave packet mode and compose arbitrarily large Fock states with a finite total success probability >96.7%.
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2
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Mechler M, Man’ko MA, Man’ko VI, Adam P. Even and Odd Cat States of Two and Three Qubits in the Probability Representation of Quantum Mechanics. ENTROPY (BASEL, SWITZERLAND) 2024; 26:485. [PMID: 38920494 PMCID: PMC11202595 DOI: 10.3390/e26060485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 05/27/2024] [Accepted: 05/29/2024] [Indexed: 06/27/2024]
Abstract
We derive the probability representation of even and odd cat states of two and three qubits. These states are even and odd superpositions of spin-1/2 eigenstates corresponding to two opposite directions along the z axis. The probability representation of even and odd cat states of an oscillating spin-1/2 particle is also discussed. The exact formulas for entangled probability distributions describing density matrices of all these states are obtained.
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Affiliation(s)
- Matyas Mechler
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary;
- Institute of Physics, University of Pécs, Ifjúság Útja 6, H-7624 Pécs, Hungary
| | - Margarita A. Man’ko
- Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991, Russia; (M.A.M.); (V.I.M.)
| | - Vladimir I. Man’ko
- Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991, Russia; (M.A.M.); (V.I.M.)
| | - Peter Adam
- Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary;
- Institute of Physics, University of Pécs, Ifjúság Útja 6, H-7624 Pécs, Hungary
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3
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Bai JL, Xie YM, Fu Y, Yin HL, Chen ZB. Asynchronous measurement-device-independent quantum key distribution with hybrid source. OPTICS LETTERS 2023; 48:3551-3554. [PMID: 37390178 DOI: 10.1364/ol.491511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 05/26/2023] [Indexed: 07/02/2023]
Abstract
The linear constraint of secret key rate capacity is overcome by the twin-field quantum key distribution (QKD). However, the complex phase-locking and phase-tracking technique requirements throttle the real-life applications of the twin-field protocol. The asynchronous measurement-device-independent (AMDI) QKD, also called the mode-pairing QKD, protocol can relax the technical requirements and keep the similar performance of the twin-field protocol. Here, we propose an AMDI-QKD protocol with a nonclassical light source by changing the phase-randomized weak coherent state to a phase-randomized coherent-state superposition in the signal state time window. Simulation results show that our proposed hybrid source protocol significantly enhances the key rate of the AMDI-QKD protocol, while exhibiting robustness to imperfect modulation of nonclassical light sources.
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4
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Sun FX, Fang Y, He Q, Liu Y. Generating optical cat states via quantum interference of multi-path free-electron-photons interactions. Sci Bull (Beijing) 2023:S2095-9273(23)00376-6. [PMID: 37353435 DOI: 10.1016/j.scib.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/17/2023] [Accepted: 06/07/2023] [Indexed: 06/25/2023]
Abstract
The novel quantum effects induced by the free-electron-photons interaction have attracted increasing interest due to their potential applications in ultrafast quantum information processing. Here, we propose a scheme to generate optical cat states based on the quantum interference of multi-path free-electron-photons interactions that take place simultaneously with strong coupling strength. By performing a projection measurement on the electron, the state of light changes significantly from a coherent state into a non-Gaussian state with either Wigner negativity or squeezing property, both possess metrological power to achieve quantum advantage. More importantly, we show that the Wigner negativity oscillates with the coupling strength, and the optical cat states are successfully generated with high fidelity at all the oscillation peaks. This oscillation reveals the quantum interference effect of the multiple quantum pathways in the interaction of the electron with photons, by that various nonclassical states of light are promising to be fast prepared and manipulated. These findings inspire further exploration of emergent quantum phenomena and advanced quantum technologies with free electrons.
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Affiliation(s)
- Feng-Xiao Sun
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Yiqi Fang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
| | - Qiongyi He
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China; Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, China; Hefei National Laboratory, Hefei 230088, China.
| | - Yunquan Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China; Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, China; Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
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5
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Endo M, He R, Sonoyama T, Takahashi K, Kashiwazaki T, Umeki T, Takasu S, Hattori K, Fukuda D, Fukui K, Takase K, Asavanant W, Marek P, Filip R, Furusawa A. Non-Gaussian quantum state generation by multi-photon subtraction at the telecommunication wavelength. OPTICS EXPRESS 2023; 31:12865-12879. [PMID: 37157437 DOI: 10.1364/oe.486270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
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.
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6
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Grebien S, Göttsch J, Hage B, Fiurášek J, Schnabel R. Multistep Two-Copy Distillation of Squeezed States via Two-Photon Subtraction. PHYSICAL REVIEW LETTERS 2022; 129:273604. [PMID: 36638289 DOI: 10.1103/physrevlett.129.273604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
Squeezed states are nonclassical resources of quantum cryptography and photonic quantum computing. The higher the squeeze factor, the greater the quantum advantage. Limitations are set by the effective nonlinearity of the pumped medium and energy loss on the squeezed states produced. Here, we experimentally analyze for the first time the multistep distillation of squeezed states that in the ideal case can approach an infinite squeeze factor. Heralded by the probabilistic subtraction of two photons, the first step increased our squeezing from 2.4 to 2.8 dB. The second step was a two-copy Gaussification, which we emulated. For this, we simultaneously measured orthogonal quadratures of the distilled state and found by probabilistic postprocessing an enhancement from 2.8 to 3.4 dB. Our new approach is able to increase the squeeze factor beyond the limit set by the effective nonlinearity of the pumped medium.
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Affiliation(s)
- Stephan Grebien
- Institut für Laserphysik & Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Julian Göttsch
- Institut für Laserphysik & Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Boris Hage
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
| | - Jaromír Fiurášek
- Department of Optics, Faculty of Science, Palacký University, 17. listopadu 12, 77900 Olomouc, Czech Republic
| | - Roman Schnabel
- Institut für Laserphysik & Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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7
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Xin J, Li G. Remote switch for Schrödinger's cat state using Einstein-Podolsky-Rosen entanglement. OPTICS EXPRESS 2022; 30:39985-39995. [PMID: 36298939 DOI: 10.1364/oe.471080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
We propose a 'remote switch' for Schrödinger's cat state (SCS). Resorting to nonlocal correlations, we demonstrate that an approximate SCS can be heralded at one mode of an Einstein-Podolsky-Rosen entangled state, via a conditional 'hybrid projective measurement' (HPM) performed on the other one mode. The HPM is able to fully manipulate both size and parity of the generated SCS. Here, the HPM consists of both photon number measurement and homodyne conditioning. Such a remote switch for SCS will open up new ideas in subsequent protocols, including fundamental tests and nonlocal manipulation of non-Gaussian states.
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8
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Generation of Long-Term Stable Squeezed Vacuum States Using Dither-Locking Technique. PHOTONICS 2022. [DOI: 10.3390/photonics9070472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We report the generation of long-term stable squeezed vacuum states at 1064 nm using a degenerate optical parametric amplifier (DOPA) with a periodically poled KTiOPO4 crystal (PPKTP). The OPA is pumped by a 532 nm light produced by frequency doubling the fundamental light with a bow-tie enhancement second harmonic generator (SHG). When the DOPA and relative phases are locked using a dither-locking method, the squeezed vacuum states are stably measured over 2 h at 11 MHz. The highly compact and simple squeezed light source is suitable for applications in quantum optics experiments.
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9
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Kawasaki A, Takase K, Nomura T, Miki S, Terai H, Yabuno M, China F, Asavanant W, Endo M, Yoshikawa JI, Furusawa A. Generation of highly pure single-photon state at telecommunication wavelength. OPTICS EXPRESS 2022; 30:24831-24840. [PMID: 36237027 DOI: 10.1364/oe.460583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 06/15/2022] [Indexed: 06/16/2023]
Abstract
Telecommunication wavelength with well-developed optical communication technologies and low losses in the waveguide are advantageous for quantum applications. However, an experimental generation of non-classical states called non-Gaussian states at the telecommunication wavelength is still underdeveloped. Here, we generate highly-pure-single-photon states, one of the most primitive non-Gaussian states, by using a heralding scheme with an optical parametric oscillator and a superconducting nano-strip photon detector. The Wigner negativity, the indicator of non-classicality, of the generated single photon state is -0.228 ± 0.004, corresponded to 85.1 ± 0.7% of single photon and the best record of the minimum value at all wavelengths. The quantum-optics-technology we establish can be easily applied to the generation of various types of quantum states, opening up the possibility of continuous-variable-quantum-information processing at the telecommunication wavelength.
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10
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Li B, Qin W, Jiao YF, Zhai CL, Xu XW, Kuang LM, Jing H. Optomechanical Schrödinger cat states in a cavity Bose-Einstein condensate. FUNDAMENTAL RESEARCH 2022. [DOI: 10.1016/j.fmre.2022.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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11
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Fukui K, Takeda S, Endo M, Asavanant W, Yoshikawa JI, van Loock P, Furusawa A. Efficient Backcasting Search for Optical Quantum State Synthesis. PHYSICAL REVIEW LETTERS 2022; 128:240503. [PMID: 35776478 DOI: 10.1103/physrevlett.128.240503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/19/2022] [Indexed: 06/15/2023]
Abstract
Non-Gaussian states are essential for many optical quantum technologies. The so-called optical quantum state synthesizer (OQSS), consisting of Gaussian input states, linear optics, and photon-number resolving detectors, is a promising method for non-Gaussian state preparation. However, an inevitable and crucial problem is the complexity of the numerical simulation of the state preparation on a classical computer. This problem makes it very challenging to generate important non-Gaussian states required for advanced quantum information processing. Thus, an efficient method to design OQSS circuits is highly desirable. To circumvent the problem, we offer a scheme employing a backcasting approach, where the circuit of OQSS is divided into some sublayers, and we simulate the OQSS backwards from final to first layers. Moreover, our results show that the detected photon number by each detector is at most 2, which can significantly reduce the requirements for the photon-number resolving detector. By virtue of the potential for the preparation of a wide variety of non-Gaussian states, the proposed OQSS can be a key ingredient in general optical quantum information processing.
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Affiliation(s)
- Kosuke Fukui
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shuntaro Takeda
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Mamoru Endo
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Warit Asavanant
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Jun-Ichi Yoshikawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Peter van Loock
- Institute of Physics, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Akira Furusawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Optical Quantum Computing Research Team, RIKEN Center for Quantum Computing, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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12
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Liu S, Han D, Wang N, Xiang Y, Sun F, Wang M, Qin Z, Gong Q, Su X, He Q. Experimental Demonstration of Remotely Creating Wigner Negativity via Quantum Steering. PHYSICAL REVIEW LETTERS 2022; 128:200401. [PMID: 35657859 DOI: 10.1103/physrevlett.128.200401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/16/2022] [Accepted: 04/21/2022] [Indexed: 06/15/2023]
Abstract
Non-Gaussian states with Wigner negativity are of particular interest in quantum technology due to their potential applications in quantum computing and quantum metrology. However, how to create such states at a remote location remains a challenge, which is important for efficiently distributing quantum resource between distant nodes in a network. Here, we experimentally prepare an optical non-Gaussian state with negative Wigner function at a remote node via local non-Gaussian operation and shared Gaussian entangled state existing quantum steering. By performing photon subtraction on one mode, Wigner negativity is created in the remote target mode. We show that the Wigner negativity is sensitive to loss on the target mode, but robust to loss on the mode performing photon subtraction. This experiment confirms the connection between the remotely created Wigner negativity and quantum steering. As an application, we present that the generated non-Gaussian state exhibits metrological power in quantum phase estimation.
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Affiliation(s)
- Shuheng Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Dongmei Han
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Na Wang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Yu Xiang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Fengxiao Sun
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Meihong Wang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Zhongzhong Qin
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, Jiangsu, China
| | - Xiaolong Su
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Qiongyi He
- State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, Jiangsu, China
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13
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Takase K, Kawasaki A, Jeong BK, Endo M, Kashiwazaki T, Kazama T, Enbutsu K, Watanabe K, Umeki T, Miki S, Terai H, Yabuno M, China F, Asavanant W, Yoshikawa JI, Furusawa A. Generation of Schrödinger cat states with Wigner negativity using a continuous-wave low-loss waveguide optical parametric amplifier. OPTICS EXPRESS 2022; 30:14161-14171. [PMID: 35473166 DOI: 10.1364/oe.454123] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
Continuous-wave (CW) squeezed light is used in the generation of various optical quantum states, and thus is a fundamental resource of fault-tolerant universal quantum computation using optical continuous variables. To realize a practical quantum computer, a waveguide optical parametric amplifier (OPA) is an attractive CW squeezed light source in terms of its THz-order bandwidth and suitability for modularization. The usages of a waveguide OPA in quantum applications thus far, however, are limited due to the difficulty of the generation of the squeezed light with a high purity. In this paper, we report the first observation of Wigner negativity of the states generated by a heralding method using a waveguide OPA. We generate Schrödinger cat states at the wavelength of 1545 nm with Wigner negativity using a quasi-single-mode ZnO-doped periodically poled LiNbO3 waveguide module we developed. Wigner negativity is regarded as an important indicator of the usefulness of the quantum states as it is essential in the fault-tolerant universal quantum computation. Our result shows that our waveguide OPA can be used in wide range of quantum applications leading to a THz-clock optical quantum computer.
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14
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Fiurášek J. Teleportation-based noiseless quantum amplification of coherent states of light. OPTICS EXPRESS 2022; 30:1466-1489. [PMID: 35209306 DOI: 10.1364/oe.443389] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
We propose and theoretically analyze a teleportation-based scheme for the high-fidelity noiseless quantum amplification of coherent states of light. In our approach, the probabilistic noiseless quantum amplification operation is encoded into a suitable auxiliary two-mode entangled state and then applied to the input coherent state via continuous-variable quantum teleportation. The scheme requires conditioning on the outcomes of homodyne measurements in the teleportation protocol. In contrast to high-fidelity noiseless quantum amplifiers based on combination of conditional single-photon addition and subtraction, the present scheme requires only photon subtraction in combination with auxiliary Gaussian squeezed vacuum states. We first provide a pure-state description of the protocol which allows us to to clearly explain its principles and functioning. Next we develop a more comprehensive model based on phase-space representation of quantum states, that accounts for various experimental imperfections such as excess noise in the auxiliary squeezed states or limited efficiency of the single-photon detectors that can only distinguish the presence or absence of photons. We present and analyze predictions of this phase-space model of the noiseless teleamplifier.
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15
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Enzian G, Freisem L, Price JJ, Svela AØ, Clarke J, Shajilal B, Janousek J, Buchler BC, Lam PK, Vanner MR. Non-Gaussian Mechanical Motion via Single and Multiphonon Subtraction from a Thermal State. PHYSICAL REVIEW LETTERS 2021; 127:243601. [PMID: 34951800 DOI: 10.1103/physrevlett.127.243601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
Quantum optical measurement techniques offer a rich avenue for quantum control of mechanical oscillators via cavity optomechanics. In particular, a powerful yet little explored combination utilizes optical measurements to perform heralded non-Gaussian mechanical state preparation followed by tomography to determine the mechanical phase-space distribution. Here, we experimentally perform heralded single-phonon and multiphonon subtraction via photon counting to a laser-cooled mechanical thermal state with a Brillouin optomechanical system at room temperature and use optical heterodyne detection to measure the s-parametrized Wigner distribution of the non-Gaussian mechanical states generated. The techniques developed here advance the state of the art for optics-based tomography of mechanical states and will be useful for a broad range of applied and fundamental studies that utilize mechanical quantum-state engineering and tomography.
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Affiliation(s)
- G Enzian
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
- Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - L Freisem
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - J J Price
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - A Ø Svela
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
- Max Planck Institute for the Science of Light, Staudtstaße 2, 91058 Erlangen, Germany
| | - J Clarke
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - B Shajilal
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - J Janousek
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - B C Buchler
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - P K Lam
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - M R Vanner
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
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16
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Hybrid Entanglement between Optical Discrete Polarizations and Continuous Quadrature Variables. PHOTONICS 2021. [DOI: 10.3390/photonics8120552] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
By coherently combining advantages while largely avoiding limitations of two mainstream platforms, optical hybrid entanglement involving both discrete and continuous variables has recently garnered widespread attention and emerged as a promising idea for building heterogenous quantum networks. In contrast to previous results, here we propose a new scheme to remotely generate hybrid entanglement between discrete polarization and continuous quadrature optical qubits heralded by two-photon Bell-state measurement. As a novel nonclassical light resource, we further use it to discuss two examples of ways—entanglement swapping and quantum teleportation—in which quantum information processing and communications could make use of this hybrid technique.
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17
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Controlled multi-photon subtraction with cascaded Rydberg superatoms as single-photon absorbers. Nat Commun 2021; 12:4328. [PMID: 34267206 PMCID: PMC8282843 DOI: 10.1038/s41467-021-24522-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/23/2021] [Indexed: 12/03/2022] Open
Abstract
The preparation of light pulses with well-defined quantum properties requires precise control at the individual photon level. Here, we demonstrate exact and controlled multi-photon subtraction from incoming light pulses. We employ a cascaded system of tightly confined cold atom ensembles with strong, collectively enhanced coupling of photons to Rydberg states. The excitation blockade resulting from interactions between Rydberg atoms limits photon absorption to one per ensemble and rapid dephasing of the collective excitation suppresses stimulated re-emission of the photon. We experimentally demonstrate subtraction with up to three absorbers. Furthermore, we present a thorough theoretical analysis of our scheme where we identify weak Raman decay of the long-lived Rydberg state as the main source of infidelity in the subtracted photon number and investigate the performance of the multi-photon subtractor for increasing absorber numbers in the presence of Raman decay. Interaction of photons with Rydberg atoms can be used to modify quantum states of light. Here the authors demonstrate a controlled nonlinear quantum behavior of multi-photon subtraction in a cascaded system based on Rydberg superatoms.
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18
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Tyagi G, Panigrahi PK. Photon added cat state: phase space structure and statistics. OPTICS LETTERS 2021; 46:1177-1180. [PMID: 33649686 DOI: 10.1364/ol.415713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
The phase space structure and statistics of the photon added cat state are studied in the state's general form. Photon addition leads to a π phase shift at the origin in the observed phase space interference of the Wigner function, which may serve as an error syndrome detector. The maxima and minima of the sub-Planck tiles in the phase space of the kitten state are interchanged after photon addition, leading to their orthogonality. Interestingly, photon addition to the Yurke-Stoler state characterized by Poissonian statistics leads to a sub-Poissonian distribution, which may find potential use in quantum noise reduction.
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Hloušek J, Ježek M, Fiurášek J. Direct Experimental Certification of Quantum Non-Gaussian Character and Wigner Function Negativity of Single-Photon Detectors. PHYSICAL REVIEW LETTERS 2021; 126:043601. [PMID: 33576686 DOI: 10.1103/physrevlett.126.043601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Highly nonclassical character of optical quantum detectors, such as single-photon detectors, is essential for preparation of quantum states of light and a vast majority of applications in quantum metrology and quantum information processing. Therefore, it is both fundamentally interesting and practically relevant to investigate the nonclassical features of optical quantum measurements. Here we propose and experimentally demonstrate a procedure for direct certification of quantum non-Gaussianity and Wigner function negativity, two crucial nonclassicality levels, of photonic quantum detectors. Remarkably, we characterize the highly nonclassical properties of the detector by probing it with only two classical thermal states and a vacuum state. We experimentally demonstrate the quantum non-Gaussianity of a single-photon avalanche diode even under the presence of background noise, and we also certify the negativity of the Wigner function of this detector. Our results open the way for direct benchmarking of photonic quantum detectors with a few measurements on classical states.
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Affiliation(s)
- Josef Hloušek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
| | - Miroslav Ježek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
| | - Jaromír Fiurášek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
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20
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Enzian G, Price JJ, Freisem L, Nunn J, Janousek J, Buchler BC, Lam PK, Vanner MR. Single-Phonon Addition and Subtraction to a Mechanical Thermal State. PHYSICAL REVIEW LETTERS 2021; 126:033601. [PMID: 33543972 DOI: 10.1103/physrevlett.126.033601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
Adding or subtracting a single quantum of excitation to a thermal state of a bosonic system has the counter-intuitive effect of approximately doubling its mean occupation. We perform the first experimental demonstration of this effect outside optics by implementing single-phonon addition and subtraction to a thermal state of a mechanical oscillator via Brillouin optomechanics in an optical whispering-gallery microresonator. Using a detection scheme that combines single-photon counting and optical heterodyne detection, we observe this doubling of the mechanical thermal fluctuations to a high precision. The capabilities of this joint click-dyne detection scheme adds a significant new dimension for optomechanical quantum science and applications.
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Affiliation(s)
- G Enzian
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
- Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - J J Price
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - L Freisem
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - J Nunn
- Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - J Janousek
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - B C Buchler
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - P K Lam
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - M R Vanner
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
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21
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Li F, Li T, Agarwal GS. Temporal quantum noise reduction acquired by an electron-multiplying charge-coupled-device camera. OPTICS EXPRESS 2020; 28:37538-37545. [PMID: 33379586 DOI: 10.1364/oe.408795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/17/2020] [Indexed: 06/12/2023]
Abstract
Electron-multiplying charge-coupled-device cameras (EMCCDs) have been used to observe quantum noise reductions in beams of light in the transverse spatial degree of freedom. For the quantum noise reduction in the temporal domain, 'bucket detectors,' usually composed of photodiodes with operational amplifiers, are used to register the intensity fluctuations in beams of light within the detectors' bandwidth. Here, we report on measurements of the temporal quantum noise reduction in bright twin beams using an EMCCD camera. The four-wave mixing process in an atomic rubidium vapor cell is used to generate the bright twin beams of light. We observe ∼ 25% of temporal quantum noise reduction with respect to the shot-noise limit in images captured by the EMCCD camera. The temporal images captured by our technique are potentially important in obtaining dynamical information on evolving systems.
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Parker RC, Joo J, Spiller TP. Photonic hybrid state entanglement swapping using cat state superpositions. Proc Math Phys Eng Sci 2020; 476:20200237. [PMID: 33363438 PMCID: PMC7735306 DOI: 10.1098/rspa.2020.0237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 10/13/2020] [Indexed: 12/03/2022] Open
Abstract
We propose the use of hybrid entanglement in an entanglement swapping protocol, as means of distributing a Bell state with high fidelity to two parties. The hybrid entanglement used in this work is described as a discrete variable (Fock state) and a continuous variable (cat state super- position) entangled state. We model equal and unequal levels of photonic loss between the two propagating continuous variable modes, before detecting these states via a projective vacuum-one-photon measurement, and the other mode via balanced homodyne detection. We investigate homodyne measurement imperfections, and the associated success probability of the measurement schemes chosen in this protocol. We show that our entanglement swapping scheme is resilient to low levels of photonic losses, as well as low levels of averaged unequal losses between the two propagating modes, and show an improvement in this loss resilience over other hybrid entanglement schemes using coherent state superpositions as the propagating modes. Finally, we conclude that our protocol is suitable for potential quantum networking applications which require two nodes to share entanglement separated over a distance of 5 -- 10 km , when used with a suitable entanglement purification scheme.
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Affiliation(s)
- Ryan C. Parker
- York Centre for Quantum Technologies, Department of Physics, University of York, York YO10 5DD, UK
| | - Jaewoo Joo
- School of Mathematics and Physics, University of Portsmouth, Portsmouth PO1 3QL, UK
| | - Timothy P. Spiller
- York Centre for Quantum Technologies, Department of Physics, University of York, York YO10 5DD, UK
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Cimini V, Barbieri M, Treps N, Walschaers M, Parigi V. Neural Networks for Detecting Multimode Wigner Negativity. PHYSICAL REVIEW LETTERS 2020; 125:160504. [PMID: 33124838 DOI: 10.1103/physrevlett.125.160504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/20/2020] [Accepted: 09/16/2020] [Indexed: 06/11/2023]
Abstract
The characterization of quantum features in large Hilbert spaces is a crucial requirement for testing quantum protocols. In the continuous variable encoding, quantum homodyne tomography requires an amount of measurement that increases exponentially with the number of involved modes, which practically makes the protocol intractable even with few modes. Here, we introduce a new technique, based on a machine learning protocol with artificial neural networks, that allows us to directly detect negativity of the Wigner function for multimode quantum states. We test the procedure on a whole class of numerically simulated multimode quantum states for which the Wigner function is known analytically. We demonstrate that the method is fast, accurate, and more robust than conventional methods when limited amounts of data are available. Moreover, the method is applied to an experimental multimode quantum state, for which an additional test of resilience to losses is carried out.
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Affiliation(s)
- Valeria Cimini
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
| | - Marco Barbieri
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
| | - Nicolas Treps
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4 place Jussieu, F-75252 Paris, France
| | - Mattia Walschaers
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4 place Jussieu, F-75252 Paris, France
| | - Valentina Parigi
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4 place Jussieu, F-75252 Paris, France
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24
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Guccione G, Darras T, Le Jeannic H, Verma VB, Nam SW, Cavaillès A, Laurat J. Connecting heterogeneous quantum networks by hybrid entanglement swapping. SCIENCE ADVANCES 2020; 6:eaba4508. [PMID: 32937408 PMCID: PMC10662397 DOI: 10.1126/sciadv.aba4508] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Recent advances in quantum technologies are rapidly stimulating the building of quantum networks. With the parallel development of multiple physical platforms and different types of encodings, a challenge for present and future networks is to uphold a heterogeneous structure for full functionality and therefore support modular systems that are not necessarily compatible with one another. Central to this endeavor is the capability to distribute and interconnect optical entangled states relying on different discrete and continuous quantum variables. Here, we report an entanglement swapping protocol connecting such entangled states. We generate single-photon entanglement and hybrid entanglement between particle- and wave-like optical qubits and then demonstrate the heralded creation of hybrid entanglement at a distance by using a specific Bell-state measurement. This ability opens up the prospect of connecting heterogeneous nodes of a network, with the promise of increased integration and novel functionalities.
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Affiliation(s)
- Giovanni Guccione
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-Universite PSL, Collège de France, 4 Place Jussieu, 75005 Paris, France
| | - Tom Darras
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-Universite PSL, Collège de France, 4 Place Jussieu, 75005 Paris, France
| | - Hanna Le Jeannic
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-Universite PSL, Collège de France, 4 Place Jussieu, 75005 Paris, France
| | - Varun B Verma
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA
| | - Sae Woo Nam
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA
| | - Adrien Cavaillès
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-Universite PSL, Collège de France, 4 Place Jussieu, 75005 Paris, France.
| | - Julien Laurat
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-Universite PSL, Collège de France, 4 Place Jussieu, 75005 Paris, France.
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25
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Švarc V, Hloušek J, Nováková M, Fiurášek J, Ježek M. Feedforward-enhanced Fock state conversion with linear optics. OPTICS EXPRESS 2020; 28:11634-11644. [PMID: 32403670 DOI: 10.1364/oe.385609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
Engineering quantum states of light represents a crucial task in the vast majority of photonic quantum technology applications. Direct manipulation of the number of photons in the light signal, such as single-photon subtraction and addition, proved to be an efficient strategy for the task. Here we propose an adaptive multi-photon subtraction scheme where a particular subtraction task is conditioned by all previous subtraction events in order to maximize the probability of successful subtraction. We theoretically illustrate this technique on the model example of conversion of Fock states via photon subtraction. We also experimentally demonstrate the core building block of the proposal by implementing a feedforward-assisted conversion of two-photon state to a single-photon state. Our experiment combines two elementary photon subtraction blocks where the splitting ratio of the second subtraction beam splitter is affected by the measurement result from the first subtraction block in real time using an ultra-fast feedforward loop. The reported optimized photon subtraction scheme applies to a broad range of photonic states, including highly nonclassical Fock states and squeezed light, advancing the photonic quantum toolbox.
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26
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Du J, Li W, Bajcsy M. Deterministic single-photon subtraction based on a coupled single quantum dot-cavity system. OPTICS EXPRESS 2020; 28:6835-6845. [PMID: 32225922 DOI: 10.1364/oe.378697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/14/2019] [Indexed: 06/10/2023]
Abstract
We present a scheme for realizing deterministic single-photon subtraction in a coupled single quantum dot-cavity solid-state system. The device consists of a charged quantum dot and its coupled bimodal photonic crystal cavity with a moderate magnetic field applied in a Voigt configuration. We numerically simulate injection of optical pulses into one of the cavity modes and show that the system deterministically transfers one photon into the second cavity mode for input pulses in the form of both Fock states and coherent states. This device has potential in the application of a compact and integrated solid-state based device for quantum information processing.
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27
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Hastrup J, Neergaard-Nielsen JS, Andersen UL. Deterministic generation of a four-component optical cat state. OPTICS LETTERS 2020; 45:640-643. [PMID: 32004272 DOI: 10.1364/ol.383194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/24/2019] [Indexed: 06/10/2023]
Abstract
The four-component cat state represents a particularly useful quantum state for realizing fault-tolerant continuous variable quantum computing. While such encoding has been experimentally generated and employed in the microwave regime, the states have not yet been produced in the optical regime. Here, we propose a simple linear optical circuit combined with photon counters for the generation of such optical four-component cat states. This work might pave the way for the first experimental generation of fault-tolerant optical continuous variable quantum codes.
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28
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29
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Yokoyama S, Dalla Pozza N, Serikawa T, Kuntz KB, Wheatley TA, Dong D, Huntington EH, Yonezawa H. Characterization of entangling properties of quantum measurement via two-mode quantum detector tomography using coherent state probes. OPTICS EXPRESS 2019; 27:34416-34433. [PMID: 31878489 DOI: 10.1364/oe.27.034416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
Entangled measurement is a crucial tool in quantum technology. We propose a new entanglement measure of multi-mode detection, which estimates the amount of entanglement that can be created in a measurement. To illustrate the proposed measure, we perform quantum tomography of a two-mode detector that is comprised of two superconducting nanowire single photon detectors. Our method utilizes coherent states as probe states, which can be easily prepared with accuracy. Our work shows that a separable state such as a coherent state is enough to characterize a potentially entangled detector. We investigate the entangling capability of the detector in various settings. Our proposed measure verifies that the detector makes an entangled measurement under certain conditions, and reveals the nature of the entangling properties of the detector. Since the precise characterization of a detector is essential for applications in quantum information technology, the experimental reconstruction of detector properties along with the proposed measure will be key features in future quantum information processing.
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30
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Mikheev EV, Pugin AS, Kuts DA, Podoshvedov SA, An NB. Efficient production of large-size optical Schrödinger cat states. Sci Rep 2019; 9:14301. [PMID: 31586138 PMCID: PMC6778084 DOI: 10.1038/s41598-019-50703-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 09/09/2019] [Indexed: 11/09/2022] Open
Abstract
We present novel theory of effective realization of large-size optical Schrödinger cat states, which play an important role for quantum communication and quantum computation in the optical domain using laser sources. The treatment is based on the α-representation in infinite Hilbert space which is the decomposition of an arbitrary quantum state in terms of displaced number states characterized by the displacement amplitude α. We find analytical form of the α-representation for both even and odd Schrödinger cat states which is essential for their generation schemes. Two schemes are proposed for generating even/odd Schrödinger cat states of large size |β| (|β| ≥ 2) with high fidelity F (F ≈ 0.99). One scheme relies on an initially offline prepared two-mode entangled state with a fixed total photon number, while the other scheme uses separable photon Fock states as the input. In both schemes, generation of the desired states is heralded by the corresponding measurement outcomes. Conditions for obtaining states useful for quantum information processing are established and success probabilities for their generation are evaluated.
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Affiliation(s)
- Evgeny V Mikheev
- Laboratory of Quantum Information Processing and Quantum Computing, Institute of Natural and Exact Sciences, South Ural State University (SUSU), Lenin Av. 76, Chelyabinsk, Russia
| | - Alexander S Pugin
- Laboratory of Quantum Information Processing and Quantum Computing, Institute of Natural and Exact Sciences, South Ural State University (SUSU), Lenin Av. 76, Chelyabinsk, Russia
- Department of Applied Mathematics and Programming, Institute of Natural and Exact Sciences, South Ural State University (SUSU), Lenin Av. 76, Chelyabinsk, Russia
| | - Dmitry A Kuts
- Laboratory of Quantum Information Processing and Quantum Computing, Institute of Natural and Exact Sciences, South Ural State University (SUSU), Lenin Av. 76, Chelyabinsk, Russia
| | - Sergey A Podoshvedov
- Laboratory of Quantum Information Processing and Quantum Computing, Institute of Natural and Exact Sciences, South Ural State University (SUSU), Lenin Av. 76, Chelyabinsk, Russia.
| | - Nguyen Ba An
- Thang Long Institute of Mathematics and Applied Sciences (TIMAS), Thang Long University (TLU), Nghiem Xuan Yem, Hoang Mai, Hanoi, Vietnam.
- Institute of Physics, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam.
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Katamadze KG, Kovlakov EV, Avosopiants GV, Kulik SP. Direct test of the "quantum vampire's" shadow absence with use of thermal light. OPTICS LETTERS 2019; 44:3286-3289. [PMID: 31259941 DOI: 10.1364/ol.44.003286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 05/20/2019] [Indexed: 06/09/2023]
Abstract
The counterintuitive nature of quantum physics leads to a number of paradoxes. One of them is a "quantum vampire" effect [Fedorov et al., Optica2, 112 (2015)OPTIC82334-253610.1364/OPTICA.2.000112], which means that the photon annihilation in a part of a large beam does not change the shape of the beam profile (i.e., does not cast a shadow), but it may change the total beam intensity. Previously, this effect was demonstrated just in a simplified double-mode regime [Fedorov et al., Optica2, 112 (2015), OPTIC82334-253610.1364/OPTICA.2.000112 Katamadze et al., Optica5, 723 (2018)OPTIC82334-253610.1364/OPTICA.5.000723]. In this Letter, a direct test of shadow absence after the photon annihilation was performed using the thermal state of light at the input.
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32
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Li Z, Tian Y, Wang Y, Ma W, Zheng Y. Residual amplitude modulation and its mitigation in wedged electro-optic modulator. OPTICS EXPRESS 2019; 27:7064-7071. [PMID: 30876278 DOI: 10.1364/oe.27.007064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 02/15/2019] [Indexed: 06/09/2023]
Abstract
We theoretically analyze and experimentally investigate the dependence of residual amplitude modulation (RAM) on the beam radius within the electro-optic crystal (EOC), the wedge angle of the EOC and the overlap efficiency between the extraordinary and ordinary beams, and the overlap efficiency is determined by the distance from the wedge facet to the downstream polarizer. The results show that the RAM with the maximum optical path difference Δ at the edge of light spot presents a sinc-like curve,and the magnitude of Δ is directly proportional to the beam radius and the wedge angle. As a scaling factor, with the decrease of the overlap efficiency between the ordinary and extraordinary beams, the RAM can be further reduced.
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33
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Quantum-enhanced sensing using non-classical spin states of a highly magnetic atom. Nat Commun 2018; 9:4955. [PMID: 30470745 PMCID: PMC6251866 DOI: 10.1038/s41467-018-07433-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/26/2018] [Indexed: 11/08/2022] Open
Abstract
Coherent superposition states of a mesoscopic quantum object play a major role in our understanding of the quantum to classical boundary, as well as in quantum-enhanced metrology and computing. However, their practical realization and manipulation remains challenging, requiring a high degree of control of the system and its coupling to the environment. Here, we use dysprosium atoms-the most magnetic element in its ground state-to realize coherent superpositions between electronic spin states of opposite orientation, with a mesoscopic spin size J = 8. We drive coherent spin states to quantum superpositions using non-linear light-spin interactions, observing a series of collapses and revivals of quantum coherence. These states feature highly non-classical behavior, with a sensitivity to magnetic fields enhanced by a factor 13.9(1.1) compared to coherent spin states-close to the Heisenberg limit 2J = 16-and an intrinsic fragility to environmental noise.
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34
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Serikawa T, Yoshikawa JI, Takeda S, Yonezawa H, Ralph TC, Huntington EH, Furusawa A. Generation of a Cat State in an Optical Sideband. PHYSICAL REVIEW LETTERS 2018; 121:143602. [PMID: 30339432 DOI: 10.1103/physrevlett.121.143602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Indexed: 06/08/2023]
Abstract
We propose a method to subtract a photon from a double sideband mode of continuous-wave light. The central idea is to use phase modulation as a frequency sideband beam splitter in the heralding photon subtraction scheme, where a small portion of the sideband mode is down-converted to 0 Hz to provide a trigger photon. An optical cat state is created by applying the proposed method to a squeezed state at 500 MHz sideband, which is generated by an optical parametric oscillator. The Wigner function of the cat state reconstructed from a direct homodyne measurement of the 500 MHz sideband modes shows the negativity of W(0,0)=-0.088±0.001 without any loss corrections.
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Affiliation(s)
- Takahiro Serikawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Jun-Ichi Yoshikawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Shuntaro Takeda
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Hidehiro Yonezawa
- School of Engineering and Information Technology, The University of New South Wales, Canberra, Australian Capital Territory 2600, Australia
- Center for Quantum Computation and Communication Technology, Australian Research Council, Canberra, Australian Capital Territory 2609, Australia
| | - Timothy C Ralph
- Center for Quantum Computation and Communication Technology, Australian Research Council, Canberra, Australian Capital Territory 2609, Australia
- School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Elanor H Huntington
- Center for Quantum Computation and Communication Technology, Australian Research Council, Canberra, Australian Capital Territory 2609, Australia
- Research School of Engineering, College of Engineering and Computer Science, Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Akira Furusawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
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35
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Silva JLE, Glancy S, Vasconcelos HM. Quadrature histograms in maximum-likelihood quantum state tomography. PHYSICAL REVIEW. A 2018; 98:022325. [PMID: 30997440 PMCID: PMC6463478 DOI: 10.1103/physreva.98.022325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Quantum state tomography aims to determine the quantum state of a system from measured data and is an essential tool for quantum information science. When dealing with continuous variable quantum states of light, tomography is often done by measuring the field amplitudes at different optical phases using homodyne detection. The quadrature-phase homodyne measurement outputs a continuous variable, so to reduce the computational cost of tomography, researchers often discretize the measurements. We show that this can be done without significantly degrading the fidelity between the estimated state and the true state. This paper studies different strategies for determining the histogram bin widths. We show that computation time can be significantly reduced with little loss in the fidelity of the estimated state when the measurement operators corresponding to each histogram bin are integrated over the bin width.
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Affiliation(s)
- J. L. E. Silva
- Departamento de Engenharia de Teleinformática, Universidade Federal do Ceará, Fortaleza, Ceará, 60440, Brazil
| | - S. Glancy
- Applied and Computational Mathematics Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - H. M. Vasconcelos
- Departamento de Engenharia de Teleinformática, Universidade Federal do Ceará, Fortaleza, Ceará, 60440, Brazil
- Applied and Computational Mathematics Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
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36
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Projective measurement onto arbitrary superposition of weak coherent state bases. Sci Rep 2018; 8:2999. [PMID: 29445101 PMCID: PMC5813249 DOI: 10.1038/s41598-018-21092-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/25/2018] [Indexed: 11/17/2022] Open
Abstract
One of the peculiar features in quantum mechanics is that a superposition of macroscopically distinct states can exist. In optical system, this is highlighted by a superposition of coherent states (SCS), i.e. a superposition of classical states. Recently this highly nontrivial quantum state and its variant have been demonstrated experimentally. Here we demonstrate the superposition of coherent states in quantum measurement which is also a key concept in quantum mechanics. More precisely, we propose and implement a projection measurement onto an arbitrary superposition of two weak coherent states in optical system. The measurement operators are reconstructed experimentally by a novel quantum detector tomography protocol. Our device is realized by combining the displacement operation and photon counting, well established technologies, and thus has implications in various optical quantum information processing applications.
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37
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Synthetic-lattice enabled all-optical devices based on orbital angular momentum of light. Nat Commun 2017; 8:16097. [PMID: 28706215 PMCID: PMC5519981 DOI: 10.1038/ncomms16097] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 05/30/2017] [Indexed: 11/15/2022] Open
Abstract
All-optical photonic devices are crucial for many important photonic technologies and applications, ranging from optical communication to quantum information processing. Conventional design of all-optical devices is based on photon propagation and interference in real space, which may rely on large numbers of optical elements, and the requirement of precise control makes this approach challenging. Here we propose an unconventional route for engineering all-optical devices using the photon’s internal degrees of freedom, which form photonic crystals in such synthetic dimensions for photon propagation and interference. We demonstrate this design concept by showing how important optical devices such as quantum memory and optical filters can be realized using synthetic orbital angular momentum (OAM) lattices in degenerate cavities. The design route utilizing synthetic photonic lattices may significantly reduce the requirement for numerous optical elements and their fine tuning in conventional design, paving the way for realistic all-optical photonic devices with novel functionalities. Design of all-optical devices rely on large numbers of optical elements and precise control makes this approach challenging. The authors demonstrate that optical devices such as quantum memory and optical filters can be realized using synthetic orbital angular momentum lattices in a single main degenerate cavity.
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38
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Costanzo LS, Coelho AS, Biagi N, Fiurášek J, Bellini M, Zavatta A. Measurement-Induced Strong Kerr Nonlinearity for Weak Quantum States of Light. PHYSICAL REVIEW LETTERS 2017; 119:013601. [PMID: 28731763 DOI: 10.1103/physrevlett.119.013601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Indexed: 06/07/2023]
Abstract
Strong nonlinearity at the single photon level represents a crucial enabling tool for optical quantum technologies. Here we report on experimental implementation of a strong Kerr nonlinearity by measurement-induced quantum operations on weak quantum states of light. Our scheme coherently combines two sequences of single photon addition and subtraction to induce a nonlinear phase shift at the single photon level. We probe the induced nonlinearity with weak coherent states and characterize the output non-Gaussian states with quantum state tomography. The strong nonlinearity is clearly witnessed as a change of sign of specific off-diagonal density matrix elements in the Fock basis.
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Affiliation(s)
- Luca S Costanzo
- Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy
- LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy
| | - Antonio S Coelho
- Departamento de Engenharia Mecânica, Universidade Federal do Piauí, 64049-550 Teresina, Piauí, Brazil
| | - Nicola Biagi
- Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy
- LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy
| | - Jaromír Fiurášek
- Department of Optics, Palacký University, 17. listopadu 1192/12, CZ-771 46 Olomouc, Czech Republic
| | - Marco Bellini
- Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy
- LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy
| | - Alessandro Zavatta
- Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy
- LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy
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39
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Ulanov AE, Sychev D, Pushkina AA, Fedorov IA, Lvovsky AI. Quantum Teleportation Between Discrete and Continuous Encodings of an Optical Qubit. PHYSICAL REVIEW LETTERS 2017; 118:160501. [PMID: 28474950 DOI: 10.1103/physrevlett.118.160501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Indexed: 06/07/2023]
Abstract
The transfer of quantum information between physical systems of a different nature is a central matter in quantum technologies. Particularly challenging is the transfer between discrete and continuous degrees of freedom of various harmonic oscillator systems. Here we implement a protocol for teleporting a continuous-variable optical qubit, encoded by means of low-amplitude coherent states, onto a discrete-variable, single-rail qubit-a superposition of the vacuum and single-photon optical states-via a hybrid entangled resource. We test our protocol on a one-dimensional manifold of the input qubit space and demonstrate the mapping onto the equator of the teleported qubit's Bloch sphere with an average fidelity of 0.83±0.04. Our work opens up the way to the wide application of quantum information processing techniques where discrete- and continuous-variable encodings are combined within the same optical circuit.
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Affiliation(s)
- Alexander E Ulanov
- International Center for Quantum Optics and Quantum Technologies (Russian Quantum Center), Skolkovo, Moscow 143025, Russia
- Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Demid Sychev
- International Center for Quantum Optics and Quantum Technologies (Russian Quantum Center), Skolkovo, Moscow 143025, Russia
- Moscow State Pedagogical University, E.V. Shpolsky Chair of Theoretical Physics, M. Pirogovskaya Street 29, Moscow 119991, Russia
| | - Anastasia A Pushkina
- International Center for Quantum Optics and Quantum Technologies (Russian Quantum Center), Skolkovo, Moscow 143025, Russia
- Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Ilya A Fedorov
- International Center for Quantum Optics and Quantum Technologies (Russian Quantum Center), Skolkovo, Moscow 143025, Russia
- P. N. Lebedev Physics Institute, Leninskiy prospect 53, Moscow 119991, Russia
| | - A I Lvovsky
- International Center for Quantum Optics and Quantum Technologies (Russian Quantum Center), Skolkovo, Moscow 143025, Russia
- Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- P. N. Lebedev Physics Institute, Leninskiy prospect 53, Moscow 119991, Russia
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40
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Generation and Detection of Continuous Variable Quantum Vortex States via Compact Photonic Devices. PHOTONICS 2017. [DOI: 10.3390/photonics4010002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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41
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Goldovsky D, Jouravsky V, Pe'er A. Simple and robust phase-locking of optical cavities with > 200 KHz servo-bandwidth using a piezo-actuated mirror mounted in soft materials. OPTICS EXPRESS 2016; 24:28239-28246. [PMID: 27958535 DOI: 10.1364/oe.24.028239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present an approach to locking of optical cavities with piezoelectric actuated mirrors based on a simple and effective mechanical decoupling of the mirror and actuator from the surrounding mount. Using simple elastic materials (e.g. rubber or soft silicone gel pads) as mechanical dampers between the piezo-mirror compound and the surrounding mount, a firm and stable mounting of a relatively large mirror (8mm diameter) can be maintained that is isolated from external mechanical resonances, and is limited only by the internal piezo-mirror resonance of > 330 KHz. Our piezo lock showed positive servo gain up to 208 KHz, and a temporal response to a step interference within < 3 μs.
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42
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Serikawa T, Yoshikawa JI, Makino K, Frusawa A. Creation and measurement of broadband squeezed vacuum from a ring optical parametric oscillator. OPTICS EXPRESS 2016; 24:28383-28391. [PMID: 27958548 DOI: 10.1364/oe.24.028383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report a 65 MHz-bandwidth triangular-shaped optical parametric oscillator (OPO) for squeezed vacuum generation at 860 nm. The triangle structure of our OPO enables the round-trip length to reach 45 mm as a ring cavity, which provides a counter circulating optical path available for introducing a probe beam or generating another squeezed vacuum. Hence our OPO is suitable for the applications in high-speed quantum information processing where two or more squeezed vacua form a complicated interferometer, like continuous-variable quantum teleportation. With a homemade, broadband and low-loss homodyne detector, a direct measurement shows 8.4 dB of squeezing at 3 MHz and also 2.4 dB of squeezing at 100 MHz.
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43
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Tresp C, Zimmer C, Mirgorodskiy I, Gorniaczyk H, Paris-Mandoki A, Hofferberth S. Single-Photon Absorber Based on Strongly Interacting Rydberg Atoms. PHYSICAL REVIEW LETTERS 2016; 117:223001. [PMID: 27925746 DOI: 10.1103/physrevlett.117.223001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Indexed: 06/06/2023]
Abstract
We report on the realization of a free-space single-photon absorber, which deterministically absorbs exactly one photon from an input pulse. Our scheme is based on the saturation of an optically thick medium by a single photon due to Rydberg blockade. By converting one absorbed input photon into a stationary Rydberg excitation, decoupled from the light field through fast engineered dephasing, we blockade the full atomic cloud and change our optical medium from opaque to transparent. We show that this results in the subtraction of one photon from the input pulse over a wide range of input photon numbers. We investigate the change of the pulse shape and temporal photon statistics of the transmitted light pulses for different input photon numbers and compare the results to simulations. Based on the experimental results, we discuss the applicability of our single-photon absorber for number resolved photon detection schemes or quantum gate operations.
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Affiliation(s)
- C Tresp
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - C Zimmer
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - I Mirgorodskiy
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - H Gorniaczyk
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - A Paris-Mandoki
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - S Hofferberth
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
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44
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45
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Hoff UB, Kollath-Bönig J, Neergaard-Nielsen JS, Andersen UL. Measurement-Induced Macroscopic Superposition States in Cavity Optomechanics. PHYSICAL REVIEW LETTERS 2016; 117:143601. [PMID: 27740796 DOI: 10.1103/physrevlett.117.143601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Indexed: 06/06/2023]
Abstract
A novel protocol for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator is proposed, compatible with existing optomechanical devices operating in the bad-cavity limit. By combining a pulsed optomechanical quantum nondemolition (QND) interaction with nonclassical optical resources and measurement-induced feedback, the need for strong single-photon coupling is avoided. We outline a three-pulse sequence of QND interactions encompassing squeezing-enhanced cooling by measurement, state preparation, and tomography.
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Affiliation(s)
- Ulrich B Hoff
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
- Australian Research Council Centre of Excellence for Engineered Quantum Systems (EQuS), School of Mathematics and Physics, The University of Queensland, St. Lucia QLD 4072, Australia
| | - Johann Kollath-Bönig
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
| | | | - Ulrik L Andersen
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
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46
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Ogawa H, Ohdan H, Miyata K, Taguchi M, Makino K, Yonezawa H, Yoshikawa JI, Furusawa A. Real-Time Quadrature Measurement of a Single-Photon Wave Packet with Continuous Temporal-Mode Matching. PHYSICAL REVIEW LETTERS 2016; 116:233602. [PMID: 27341231 DOI: 10.1103/physrevlett.116.233602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 06/06/2023]
Abstract
Real-time controls based on quantum measurements are powerful tools for various quantum protocols. However, their experimental realization has been limited by mode mismatch between the temporal mode of quadrature measurement and that heralded by photon detection. Here, we demonstrate real-time quadrature measurement of a single-photon wave packet induced by photon detection by utilizing continuous temporal-mode matching between homodyne detection and an exponentially rising temporal mode. Single photons in exponentially rising modes are also expected to be useful resources for interactions with other quantum systems.
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Affiliation(s)
- Hisashi Ogawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Hideaki Ohdan
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kazunori Miyata
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Masahiro Taguchi
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kenzo Makino
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Hidehiro Yonezawa
- Centre for Quantum Computation and Communication Technology, School of Engineering and Information Technology, University of New South Wales, Canberra, Australian Capital Territory 2600, Australia
| | - Jun-Ichi Yoshikawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Akira Furusawa
- Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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47
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Joo J, Ginossar E. Efficient scheme for hybrid teleportation via entangled coherent states in circuit quantum electrodynamics. Sci Rep 2016; 6:26338. [PMID: 27245775 PMCID: PMC4887884 DOI: 10.1038/srep26338] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 04/20/2016] [Indexed: 11/29/2022] Open
Abstract
We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.
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Affiliation(s)
- Jaewoo Joo
- Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, South Korea
| | - Eran Ginossar
- Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
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48
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Tiranov A, Lavoie J, Strassmann PC, Sangouard N, Afzelius M, Bussières F, Gisin N. Demonstration of Light-Matter Micro-Macro Quantum Correlations. PHYSICAL REVIEW LETTERS 2016; 116:190502. [PMID: 27232010 DOI: 10.1103/physrevlett.116.190502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Indexed: 06/05/2023]
Abstract
Quantum mechanics predicts microscopic phenomena with undeniable success. Nevertheless, current theoretical and experimental efforts still do not yield conclusive evidence that there is or is not a fundamental limitation on the possibility to observe quantum phenomena at the macroscopic scale. This question prompted several experimental efforts producing quantum superpositions of large quantum states in light or matter. We report on the observation of quantum correlations, revealed using an entanglement witness, between a single photon and an atomic ensemble of billions of ions frozen in a crystal. The matter part of the state involves the superposition of two macroscopically distinguishable solid-state components composed of several tens of atomic excitations. Assuming the insignificance of the time ordering our experiment indirectly shows light-matter micro-macro entanglement. Our approach leverages from quantum memory techniques and could be used in other systems to expand the size of quantum superpositions in matter.
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Affiliation(s)
- Alexey Tiranov
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Jonathan Lavoie
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Peter C Strassmann
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Nicolas Sangouard
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland
| | - Mikael Afzelius
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Félix Bussières
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Nicolas Gisin
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
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49
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Liao JQ, Tian L. Macroscopic Quantum Superposition in Cavity Optomechanics. PHYSICAL REVIEW LETTERS 2016; 116:163602. [PMID: 27152802 DOI: 10.1103/physrevlett.116.163602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Indexed: 06/05/2023]
Abstract
Quantum superposition in mechanical systems is not only key evidence for macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We study systematically the generation of the Yurke-Stoler-like states in the presence of system dissipations. We also discuss the experimental implementation of this scheme.
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Affiliation(s)
- Jie-Qiao Liao
- School of Natural Sciences, University of California, Merced, California 95343, USA
| | - Lin Tian
- School of Natural Sciences, University of California, Merced, California 95343, USA
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50
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Abstract
Single-quantum level operations are important tools to manipulate a quantum state. Annihilation or creation of single particles translates a quantum state to another by adding or subtracting a particle, depending on how many are already in the given state. The operations are probabilistic and the success rate has yet been low in their experimental realization. Here we experimentally demonstrate (near) deterministic addition and subtraction of a bosonic particle, in particular a phonon of ionic motion in a harmonic potential. We realize the operations by coupling phonons to an auxiliary two-level system and applying transitionless adiabatic passage. We show handy repetition of the operations on various initial states and demonstrate by the reconstruction of the density matrices that the operations preserve coherences. We observe the transformation of a classical state to a highly non-classical one and a Gaussian state to a non-Gaussian one by applying a sequence of operations deterministically.
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