1
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Yan WZ, Li Y, Hou Z, Zhu H, Xiang GY, Li CF, Guo GC. Experimental Demonstration of Inequivalent Mutually Unbiased Bases. PHYSICAL REVIEW LETTERS 2024; 132:080202. [PMID: 38457709 DOI: 10.1103/physrevlett.132.080202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 01/12/2024] [Indexed: 03/10/2024]
Abstract
Quantum measurements based on mutually unbiased bases (MUBs) play crucial roles in foundational studies and quantum information processing. It is known that there exist inequivalent MUBs, but little is known about their operational distinctions, not to say experimental demonstration. In this Letter, by virtue of a simple estimation problem, we experimentally demonstrate the operational distinctions between inequivalent triples of MUBs in dimension 4 based on high-precision photonic systems. The experimental estimation fidelities coincide well with the theoretical predictions with only 0.16% average deviation, which is 25 times less than the difference (4.1%) between the maximum estimation fidelity and the minimum estimation fidelity. Our experiments clearly demonstrate that inequivalent MUBs have different information extraction capabilities and different merits for quantum information processing.
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Affiliation(s)
- Wen-Zhe Yan
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Yunting Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Center for Field Theory and Particle Physics, Fudan University, Shanghai 200433, China
| | - Zhibo Hou
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, People's Republic of China
| | - Huangjun Zhu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Center for Field Theory and Particle Physics, Fudan University, Shanghai 200433, China
| | - Guo-Yong Xiang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, People's Republic of China
| | - Chuan-Feng Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, People's Republic of China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, People's Republic of China
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2
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Yin XF, Yao XC, Wu B, Fei YY, Mao Y, Zhang R, Liu LZ, Wang Z, Li L, Liu NL, Wilczek F, Chen YA, Pan JW. Solving independent set problems with photonic quantum circuits. Proc Natl Acad Sci U S A 2023; 120:e2212323120. [PMID: 37216545 PMCID: PMC10235971 DOI: 10.1073/pnas.2212323120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 03/01/2023] [Indexed: 05/24/2023] Open
Abstract
An independent set (IS) is a set of vertices in a graph such that no edge connects any two vertices. In adiabatic quantum computation [E. Farhi, et al., Science 292, 472-475 (2001); A. Das, B. K. Chakrabarti, Rev. Mod. Phys. 80, 1061-1081 (2008)], a given graph G(V, E) can be naturally mapped onto a many-body Hamiltonian [Formula: see text], with edges [Formula: see text] being the two-body interactions between adjacent vertices [Formula: see text]. Thus, solving the IS problem is equivalent to finding all the computational basis ground states of [Formula: see text]. Very recently, non-Abelian adiabatic mixing (NAAM) has been proposed to address this task, exploiting an emergent non-Abelian gauge symmetry of [Formula: see text] [B. Wu, H. Yu, F. Wilczek, Phys. Rev. A 101, 012318 (2020)]. Here, we solve a representative IS problem [Formula: see text] by simulating the NAAM digitally using a linear optical quantum network, consisting of three C-Phase gates, four deterministic two-qubit gate arrays (DGA), and ten single rotation gates. The maximum IS has been successfully identified with sufficient Trotterization steps and a carefully chosen evolution path. Remarkably, we find IS with a total probability of 0.875(16), among which the nontrivial ones have a considerable weight of about 31.4%. Our experiment demonstrates the potential advantage of NAAM for solving IS-equivalent problems.
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Affiliation(s)
- Xu-Fei Yin
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Xing-Can Yao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Biao Wu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
| | - Yue-Yang Fei
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Yingqiu Mao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Rui Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Li-Zheng Liu
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Zhenduo Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Li Li
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Nai-Le Liu
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Frank Wilczek
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
- Center for Theoretical Physics, MIT, Cambridge, MA02139
- T. D. Lee Institute, Shanghai Jiao Tong University, Shanghai200240, China
- Department of Physics, Stockholm University, StockholmSE-106 91, Sweden
- Department of Physics and Origins Project, Arizona State University, Tempe, AZ25287
| | - Yu-Ao Chen
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Jian-Wei Pan
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
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3
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Wang Y, Hao ZY, Li JK, Liu ZH, Sun K, Xu JS, Li CF, Guo GC. Observation of Non-Markovian Evolution of Einstein-Podolsky-Rosen Steering. PHYSICAL REVIEW LETTERS 2023; 130:200202. [PMID: 37267573 DOI: 10.1103/physrevlett.130.200202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 03/09/2023] [Accepted: 04/24/2023] [Indexed: 06/04/2023]
Abstract
Einstein-Podolsky-Rosen (EPR) steering is a type of characteristic nonlocal correlation and provides an important resource in quantum information tasks, especially in view of its asymmetric property. Although plenty of works on EPR steering have been reported, the study of non-Markovian evolution of EPR steering, in which the interactions between the quantum system and surrounding environment are taken into consideration, still lacks intuitive experimental evidence. Here, we experimentally observe the non-Markovian evolution of EPR steering including its sudden death and revival processes, during which the degree of memory effect plays a key role in the recovery of steering. Additionally, a strict unsteerable feature is sufficiently verified during the non-Markovian evolution within multisetting measurements. This Letter, revealing the whole evolution of EPR steering under the non-Markovian process, provides incisive insight into the applications of EPR steering in quantum open systems.
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Affiliation(s)
- Yan Wang
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Ze-Yan Hao
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Jia-Kun Li
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zheng-Hao Liu
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Kai Sun
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Jin-Shi Xu
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- 3Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Chuan-Feng Li
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- 3Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Guang-Can Guo
- 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- 3Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
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4
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Sun K, Liu ZH, Wang Y, Hao ZY, Xu XY, Xu JS, Li CF, Guo GC, Castellini A, Lami L, Winter A, Adesso G, Compagno G, Lo Franco R. Activation of indistinguishability-based quantum coherence for enhanced metrological applications with particle statistics imprint. Proc Natl Acad Sci U S A 2022; 119:e2119765119. [PMID: 35594392 PMCID: PMC9173775 DOI: 10.1073/pnas.2119765119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 03/28/2022] [Indexed: 12/01/2022] Open
Abstract
SignificanceQuantum coherence has a fundamentally different origin for nonidentical and identical particles since for the latter a unique contribution exists due to indistinguishability. Here we experimentally show how to exploit, in a controllable fashion, the contribution to quantum coherence stemming from spatial indistinguishability. Our experiment also directly proves, on the same footing, the different role of particle statistics (bosons or fermions) in supplying coherence-enabled advantage for quantum metrology. Ultimately, our results provide insights toward viable quantum-enhanced technologies based on tunable indistinguishability of identical building blocks.
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Affiliation(s)
- Kai Sun
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Zheng-Hao Liu
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Yan Wang
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Ze-Yan Hao
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Xiao-Ye Xu
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Jin-Shi Xu
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Chuan-Feng Li
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Guang-Can Guo
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- Chinese Academy of Sciences Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Alessia Castellini
- Dipartimento di Fisica e Chimica–Emilio Segrè, Università di Palermo, 90123 Palermo, Italy
| | - Ludovico Lami
- Institut für Theoretische Physik, Universität Ulm, D-89069 Ulm, Germany
| | - Andreas Winter
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Universitat Autònoma de Barcelona, ES-08193 Bellaterra, Spain
- Física Teórica: Informació i Fenómens Quàntics, Departament de Física, Universitat Autònoma de Barcelona, ES-08193 Bellaterra, Spain
| | - Gerardo Adesso
- School of Mathematical Sciences, University of Nottingham, Nottingham NG/2RD, United Kingdom
- Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, University of Nottingham, Nottingham NG/2RD, United Kingdom
| | - Giuseppe Compagno
- Dipartimento di Fisica e Chimica–Emilio Segrè, Università di Palermo, 90123 Palermo, Italy
| | - Rosario Lo Franco
- Dipartimento di Ingegneria, Università di Palermo, 90128 Palermo, Italy
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5
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Sun K, Wang Y, Liu ZH, Xu XY, Xu JS, Li CF, Guo GC, Castellini A, Nosrati F, Compagno G, Lo Franco R. Experimental quantum entanglement and teleportation by tuning remote spatial indistinguishability of independent photons. OPTICS LETTERS 2020; 45:6410-6413. [PMID: 33258824 DOI: 10.1364/ol.401735] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/13/2020] [Indexed: 06/12/2023]
Abstract
Quantitative control of spatial indistinguishability of identical subsystems as a direct quantum resource at distant sites has not yet been experimentally proven. We design a setup capable of tuning remote spatial indistinguishability of two independent photons by individually adjusting their spatial distribution in two distant regions, leading to polarization entanglement from uncorrelated photons. This is achieved by spatially localized operations and classical communication on photons that meet only at the detectors. The amount of entanglement depends uniquely on the degree of spatial indistinguishability, quantified by an entropic measure I, which enables teleportation with fidelities above the classical threshold. The results open the way to viable indistinguishability-enhanced quantum information processing.
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6
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Wu KD, Bäumer E, Tang JF, Hovhannisyan KV, Perarnau-Llobet M, Xiang GY, Li CF, Guo GC. Minimizing Backaction through Entangled Measurements. PHYSICAL REVIEW LETTERS 2020; 125:210401. [PMID: 33275014 DOI: 10.1103/physrevlett.125.210401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 10/05/2020] [Indexed: 06/12/2023]
Abstract
When an observable is measured on an evolving coherent quantum system twice, the first measurement generally alters the statistics of the second one, which is known as measurement backaction. We introduce, and push to its theoretical and experimental limits, a novel method of backaction evasion, whereby entangled collective measurements are performed on several copies of the system. This method is inspired by a similar idea designed for the problem of measuring quantum work [Perarnau-Llobet et al., Phys. Rev. Lett. 118, 070601 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.070601]. By using entanglement as a resource, we show that the backaction can be extremely suppressed compared to all previous schemes. Importantly, the backaction can be eliminated in highly coherent processes.
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Affiliation(s)
- Kang-Da Wu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Elisa Bäumer
- Institute for Theoretical Physics, ETH Zurich, 8093 Zürich, Switzerland
| | - Jun-Feng Tang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Karen V Hovhannisyan
- The Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, 34151 Trieste, Italy
| | | | - Guo-Yong Xiang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Chuan-Feng Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
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7
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Jin R, Cai W, Ding C, Mei F, Deng G, Shimizu R, Zhou Q. Spectrally uncorrelated biphotons generated from “the family of BBO crystal”. ACTA ACUST UNITED AC 2020. [DOI: 10.1002/que2.38] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Rui‐Bo Jin
- Hubei Key Laboratory of Optical Information and Pattern RecognitionWuhan Institute of Technology Wuhan China
- State Key Laboratory of Quantum Optics and Quantum Optics DevicesInstitute of Laser Spectroscopy, Shanxi University Taiyuan China
| | - Wu‐Hao Cai
- Hubei Key Laboratory of Optical Information and Pattern RecognitionWuhan Institute of Technology Wuhan China
| | - Chunling Ding
- Hubei Key Laboratory of Optical Information and Pattern RecognitionWuhan Institute of Technology Wuhan China
| | - Feng Mei
- State Key Laboratory of Quantum Optics and Quantum Optics DevicesInstitute of Laser Spectroscopy, Shanxi University Taiyuan China
- Collaborative Innovation Center of Extreme OpticsShanxi University Taiyuan China
| | - Guang‐Wei Deng
- Institute of Fundamental and Frontier Sciences and School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China Chengdu China
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | | | - Qiang Zhou
- Institute of Fundamental and Frontier Sciences and School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China Chengdu China
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
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8
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Hu X, Zhang C, Zhang C, Liu B, Huang Y, Han Y, Li C, Guo G. Experimental certification for nonclassical teleportation. ACTA ACUST UNITED AC 2019. [DOI: 10.1002/que2.13] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Xiao‐Min Hu
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | - Chao Zhang
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | - Cheng‐Jie Zhang
- College of Physics, Optoelectronics and EnergySoochow University Suzhou China
| | - Bi‐Heng Liu
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | - Yun‐Feng Huang
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | - Yong‐Jian Han
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | - Chuan‐Feng Li
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
| | - Guang‐Can Guo
- CAS Key Laboratory of Quantum InformationUniversity of Science and Technology of China Hefei China
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9
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Wu KD, Yuan Y, Xiang GY, Li CF, Guo GC, Perarnau-Llobet M. Experimentally reducing the quantum measurement back action in work distributions by a collective measurement. SCIENCE ADVANCES 2019; 5:eaav4944. [PMID: 30838334 PMCID: PMC6397021 DOI: 10.1126/sciadv.aav4944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 01/14/2019] [Indexed: 06/09/2023]
Abstract
In quantum thermodynamics, the standard approach to estimating work fluctuations in unitary processes is based on two projective measurements, one performed at the beginning of the process and one at the end. The first measurement destroys any initial coherence in the energy basis, thus preventing later interference effects. To decrease this back action, a scheme based on collective measurements has been proposed by Perarnau-Llobet et al. Here, we report its experimental implementation in an optical system. The experiment consists of a deterministic collective measurement on two identically prepared qubit states, encoded in the polarization and path degree of a single photon. The standard two-projective measurement approach is also experimentally realized for comparison. Our results show the potential of collective schemes to decrease the back action of projective measurements, and capture subtle effects arising from quantum coherence.
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Affiliation(s)
- Kang-Da Wu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Yuan Yuan
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Guo-Yong Xiang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Chuan-Feng Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
| | - Martí Perarnau-Llobet
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, D-80799 München, Germany
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10
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Zhong HS, Li Y, Li W, Peng LC, Su ZE, Hu Y, He YM, Ding X, Zhang W, Li H, Zhang L, Wang Z, You L, Wang XL, Jiang X, Li L, Chen YA, Liu NL, Lu CY, Pan JW. 12-Photon Entanglement and Scalable Scattershot Boson Sampling with Optimal Entangled-Photon Pairs from Parametric Down-Conversion. PHYSICAL REVIEW LETTERS 2018; 121:250505. [PMID: 30608840 DOI: 10.1103/physrevlett.121.250505] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Indexed: 06/09/2023]
Abstract
Entangled-photon sources with simultaneously near-unity heralding efficiency and indistinguishability are the fundamental elements for scalable photonic quantum technologies. We design and realize a degenerate telecommunication wavelength entangled-photon source from an ultrafast pulsed laser pumped spontaneous parametric down-conversion (SPDC), which shows simultaneously 97% heralding efficiency and 96% indistinguishability between independent single photons without narrow-band filtering. Such a beamlike and frequency-uncorrelated SPDC source allows generation of the first 12-photon genuine entanglement with a state fidelity of 0.572±0.024. We further demonstrate a blueprint of scalable scattershot boson sampling using 12 SPDC sources and a 12×12 mode interferometer for three-, four-, and five-boson sampling, which yields count rates more than 4 orders of magnitude higher than all previous SPDC experiments.
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Affiliation(s)
- Han-Sen Zhong
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yuan Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Li-Chao Peng
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zu-En Su
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yi Hu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yu-Ming He
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xing Ding
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Weijun Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
| | - Hao Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
| | - Lu Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
| | - Zhen Wang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
| | - Lixing You
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
| | - Xi-Lin Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiao Jiang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Li Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yu-Ao Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Nai-Le Liu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chao-Yang Lu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jian-Wei Pan
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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11
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Okawa Y, Omura F, Yasutake Y, Fukatsu S. Photon heterodyning. OPTICS EXPRESS 2017; 25:20156-20161. [PMID: 29041699 DOI: 10.1364/oe.25.020156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 08/04/2017] [Indexed: 06/07/2023]
Abstract
Single-photon interference experiments are attempted in the time domain using true single-photon streams. Self-heterodyning beats are clearly observed by letting the field associated with a single photon interfere with itself on a field-quadratic detector, which is a time analogue of Young's two-slit interference experiment. The temporal first-order coherence of single-photon fields, i.e., transient interference fringes, develops as cumulative detection events are mapped point-by-point onto a virtual capture frame by properly correlating the time-series data. The ability to single out photon counts at a designated timing paves the way for digital heterodyning with faint light for such use as phase measurement and quantum information processing.
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12
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Zhang C, Zhang CJ, Huang YF, Hou ZB, Liu BH, Li CF, Guo GC. Experimental test of genuine multipartite nonlocality under the no-signalling principle. Sci Rep 2016; 6:39327. [PMID: 27996055 PMCID: PMC5171240 DOI: 10.1038/srep39327] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 11/22/2016] [Indexed: 11/21/2022] Open
Abstract
Genuine multipartite nonlocality (GMN) has been recognized as the strongest form of multipartite quantum correlation. However, there exist states that cannot violate the Svetlichny inequality derived from the standard definition of GMN, even though they possess GMN properties. The reason is that the standard definition of GMN allows correlations that permit signalling among parties, which is inconsistent with an operational definition. Here, for the first time, we present an experimental test of GMN in the no-signalling scenario, with a three-photon pure state |ψs〉 and a noisy W state. The experimental results show that these states cannot violate the Svetlichny inequality. However, our results also demonstrate that they do violate a new inequality derived from the definition of GMN based on the no-signalling principle, i.e., these states can exhibit GMN under the requirement of no-signalling. Our results will be useful for the study and applications of GMN in quantum communications and quantum computation.
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Affiliation(s)
- Chao Zhang
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P.R. China
| | - Cheng-Jie Zhang
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou, 215006, China
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
| | - Yun-Feng Huang
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P.R. China
| | - Zhi-Bo Hou
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P.R. China
| | - Bi-Heng Liu
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P.R. China
| | - Chuan-Feng Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P.R. China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P.R. China
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13
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Yang R, Li J, Song XB, Gao T, Li YR, Zhang YJ, Chen XX, Gong YX. Experimental realization of a 2 × 2 polarization-independent split-ratio-tunable optical beam splitter. OPTICS EXPRESS 2016; 24:28519-28528. [PMID: 27958496 DOI: 10.1364/oe.24.028519] [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 realized a polarization-independent split-ratio-tunable optical beam splitter supporting two input and output ports through a stable interferometer. By adjusting the angle of a half-wave plate in the interferometer, we can tune the beam splitter reflectivities for both input ports from 0 to 1, regardless of the input light polarization. High-fidelity polarization-preserving transmission from input to output ports was verified by complete quantum process tomography. Nearly optimal interference effects at the beam splitter with various split ratios were observed by two-photon Hong-Ou-Mandel interference for different input polarization states. Such a beam splitter could find a variety of applications in classical and quantum optical technologies.
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14
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Zhang C, Huang YF, Zhang CJ, Wang J, Liu BH, Li CF, Guo GC. Generation and applications of an ultrahigh-fidelity four-photon Greenberger-Horne-Zeilinger state. OPTICS EXPRESS 2016; 24:27059-27069. [PMID: 27906280 DOI: 10.1364/oe.24.027059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
High-quality entangled photon pairs generated via spontaneous parametric down-conversion have made great contributions to the modern quantum information science and the fundamental tests of quantum mechanics. However, the quality of the entangled states decreases sharply when moving from biphoton to multiphoton experiments, mainly due to the lack of interactions between photons. Here, for the first time, we generate a four-photon Greenberger-Horne-Zeilinger state with a fidelity of 98%, which is even comparable to the best fidelity of biphoton entangled states. Thus, it enables us to demonstrate an ultrahigh-fidelity entanglement swapping-the key ingredient in various quantum information tasks. Our results push the fidelity of multiphoton entanglement generation to a new level and would be useful in some demanding tasks, e.g., we successfully demonstrate the genuine multipartite nonlocality of the observed state in the nonsignaling scenario by violating a novel Hardy-like inequality, which requires very high state-fidelity.
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15
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Wang XL, Chen LK, Li W, Huang HL, Liu C, Chen C, Luo YH, Su ZE, Wu D, Li ZD, Lu H, Hu Y, Jiang X, Peng CZ, Li L, Liu NL, Chen YA, Lu CY, Pan JW. Experimental Ten-Photon Entanglement. PHYSICAL REVIEW LETTERS 2016; 117:210502. [PMID: 27911530 DOI: 10.1103/physrevlett.117.210502] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 05/28/2023]
Abstract
We report the first experimental demonstration of quantum entanglement among ten spatially separated single photons. A near-optimal entangled photon-pair source was developed with simultaneously a source brightness of ∼12 MHz/W, a collection efficiency of ∼70%, and an indistinguishability of ∼91% between independent photons, which was used for a step-by-step engineering of multiphoton entanglement. Under a pump power of 0.57 W, the ten-photon count rate was increased by about 2 orders of magnitude compared to previous experiments, while maintaining a state fidelity sufficiently high for proving the genuine ten-particle entanglement. Our work created a state-of-the-art platform for multiphoton experiments, and enabled technologies for challenging optical quantum information tasks, such as the realization of Shor's error correction code and high-efficiency scattershot boson sampling.
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Affiliation(s)
- Xi-Lin Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Luo-Kan Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - W Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - H-L Huang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - C Liu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - C Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Y-H Luo
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Z-E Su
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - D Wu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Z-D Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - H Lu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Y Hu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - X Jiang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - C-Z Peng
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - L Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - N-L Liu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Yu-Ao Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Chao-Yang Lu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
| | - Jian-Wei Pan
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China, CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China, and CAS-Alibaba Quantum Computing Laboratory, Shanghai, 201315, China
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16
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Jeong YC, Hong KH, Kim YH. Bright source of polarization-entangled photons using a PPKTP pumped by a broadband multi-mode diode laser. OPTICS EXPRESS 2016; 24:1165-1174. [PMID: 26832500 DOI: 10.1364/oe.24.001165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report a bright source of polarization-entangled photon pairs using spontaneous parametric down-conversion (SPDC) in a 10 mm long type-II PPKTP crystal pumped by a broadband multi-mode diode laser with the coherence length of 330 μm. Ordinarily, the huge mismatch between the pump coherence length and the PPKTP length would degrade the polarization entanglement completely. By employing the universal Bell-state synthesizer scheme, we remove the spectral/temporal distinguishability of the biphoton amplitudes entirely to recover high-visibility and high-fidelity two-photon polarization entanglement. The pair detection rates are 7,000 pairs/mW via single-mode fibers (with 99.2% fidelity) and 90,900 pairs/mW via multi-mode fibers (with 96.8% fidelity). We also analyze the scheme theoretically to show the effect of broadband multi-mode pumping on the phase matching condition of the type-II PPKTP.
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17
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He YQ, Ding D, Yan FL, Gao T. Exploration of photon-number entangled states using weak nonlinearities. OPTICS EXPRESS 2015; 23:21671-21677. [PMID: 26368146 DOI: 10.1364/oe.23.021671] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A method for exploring photon-number entangled states with weak nonlinearities is described. We show that it is possible to create and detect such entanglement at various scales, ranging from microscopic to macroscopic systems. In the present architecture, we suggest that the maximal phase shift induced in the process of interaction between photons is proportional to photon numbers. Also, in the absence of decoherence we analyze maximum error probability and show its feasibility with current technology.
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18
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Cao DY, Liu BH, Wang Z, Huang YF, Li CF, Guo GC. Multiuser-to-multiuser entanglement distribution based on 1550 nm polarization-entangled photons. Sci Bull (Beijing) 2015. [DOI: 10.1007/s11434-015-0801-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Jin H, Xu P, Luo XW, Leng HY, Gong YX, Yu WJ, Zhong ML, Zhao G, Zhu SN. Compact engineering of path-entangled sources from a monolithic quadratic nonlinear photonic crystal. PHYSICAL REVIEW LETTERS 2013; 111:023603. [PMID: 23889400 DOI: 10.1103/physrevlett.111.023603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Indexed: 06/02/2023]
Abstract
An integrated realization of photonic entangled states becomes an inevitable tendency toward integrated quantum optics. Here we report the compact engineering of steerable photonic path-entangled states from a monolithic quadratic nonlinear photonic crystal. The crystal acts as a coherent beam splitter to distribute photons into designed spatial modes, producing the heralded single-photon and appealing beamlike two-photon path entanglement. We characterize the path entanglement by implementing quantum spatial beating experiments. Such a multifunctional entangled source can be further extended to the high-dimensional fashion and multiphoton level, which paves a desirable way to engineering miniaturized quantum light sources.
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Affiliation(s)
- H Jin
- National Laboratory of Solid State Microstructures, College of Physics, and National Center of Microstructures and Quantum Manipulation, Nanjing University, Nanjing 210093, China
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20
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Xu JS, Li CF, Zou XB, Guo GC. Experimental violation of the Leggett-Garg inequality under decoherence. Sci Rep 2012; 1:101. [PMID: 22355619 PMCID: PMC3216586 DOI: 10.1038/srep00101] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 09/09/2011] [Indexed: 11/09/2022] Open
Abstract
Despite the great success of quantum mechanics, questions regarding its application still exist and the boundary between quantum and classical mechanics remains unclear. Based on the philosophical assumptions of macrorealism and noninvasive measurability, Leggett and Garg devised a series of inequalities (LG inequalities) involving a single system with a set of measurements at different times. Introduced as the Bell inequalities in time, the violation of LG inequalities excludes the hidden-variable description based on the above two assumptions. We experimentally investigated the single photon LG inequalities under decoherence simulated by birefringent media. These generalized LG inequalities test the evolution trajectory of the photon and are shown to be maximally violated in a coherent evolution process. The violation of LG inequalities becomes weaker with the increase of interaction time in the environment. The ability to violate the LG inequalities can be used to set a boundary of the classical realistic description.
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Affiliation(s)
- Jin-Shi Xu
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS , Hefei. 230026, China
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21
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Niu XL, Gong YX, Liu BH, Huang YF, Guo GC, Ou ZY. Observation of a generalized bunching effect of six photons. OPTICS LETTERS 2009; 34:1297-1299. [PMID: 19412251 DOI: 10.1364/ol.34.001297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
When photons are indistinguishably in the same temporal mode, their detection probability is greatly enhanced due to constructive multiphoton interference, as compared to the case when they are distinguishable. We observed for what is believed to be the first time such a photon bunching effect for six photons. The observed enhancement factor in six-photon coincidence measurement is 17+/-2, which is close to a factor of 20 for an ideal case. Our result confirms that the six photons that we obtain have a high degree of indistinguishability.
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Affiliation(s)
- Xiao-Ling Niu
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, 230026, China
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22
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Kwon O, Cho YW, Kim YH. Quantum random number generator using photon-number path entanglement. APPLIED OPTICS 2009; 48:1774-1778. [PMID: 19305476 DOI: 10.1364/ao.48.001774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report a quantum random number generator based on the photon-number-path entangled state that is prepared by means of two-photon quantum interference at a beam splitter. The randomness in our scheme is truly quantum mechanical in origin since it results from the projection measurement of the entangled two-photon state. The generated bit sequences satisfy the standard randomness test.
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Affiliation(s)
- Osung Kwon
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, South Korea
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23
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Shalm LK, Adamson RBA, Steinberg AM. Squeezing and over-squeezing of triphotons. Nature 2009; 457:67-70. [DOI: 10.1038/nature07624] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Accepted: 11/04/2008] [Indexed: 11/09/2022]
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24
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Niu XL, Huang YF, Xiang GY, Guo GC, Ou ZY. Beamlike high-brightness source of polarization-entangled photon pairs. OPTICS LETTERS 2008; 33:968-970. [PMID: 18451955 DOI: 10.1364/ol.33.000968] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We report on an ultrabright beamlike source of polarization-entangled photon pairs that is suitable for the task of multiphoton quantum information processing. The photon pairs are generated from a beamlike type-II parametric downconversion process in two adjacently located but 180 degrees rotated beta-barium borate crystals. Approximately 30,000 s(-1) entangled photon pairs are recorded experimentally with only 100 mW pump power. The fidelity of the generated entangled state as compared with a Bell state is measured to be 0.974 with the method of quantum state tomography. With this source, we also obtain a violation of Bell's inequality by 61 standard deviations in just a few seconds.
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Affiliation(s)
- Xiao-Ling Niu
- Key Laboratory of Quantum Information, Chinese Academy of Sciences (CAS), University of Science and Technology of China, Hefei 230026, China
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25
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Sun FW, Liu BH, Gong YX, Huang YF, Ou ZY, Guo GC. Stimulated emission as a result of multiphoton interference. PHYSICAL REVIEW LETTERS 2007; 99:043601. [PMID: 17678364 DOI: 10.1103/physrevlett.99.043601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Indexed: 05/16/2023]
Abstract
By performing an experiment on stimulated emission by two photons in the parametric amplification process and comparing it to a three-photon interference scheme, we present evidence in support of the idea that the underlying physics of stimulated emission is simply the constructive interference due to photon indistinguishability. So the observed signal enhancement upon the input of photons can be interpreted as a result of multiphoton interference of the input photons and the otherwise spontaneously emitted photon from the amplifier.
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Affiliation(s)
- F W Sun
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, People's Republic of China
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26
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Liu BH, Sun FW, Gong YX, Huang YF, Guo GC, Ou ZY. Four-photon interference with asymmetric beam splitters. OPTICS LETTERS 2007; 32:1320-2. [PMID: 17440574 DOI: 10.1364/ol.32.001320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Two experiments of four-photon interference are performed with two pairs of photons from parametric downconversion with the help of asymmetric beam splitters. The first experiment is a generalization of the Hong-Ou-Mandel interference effect to two pairs of photons while the second one utilizes this effect to demonstrate a four-photon de Broglie wavelength of lambda/4 by projection measurement.
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Affiliation(s)
- B H Liu
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, China
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27
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Adamson RBA, Shalm LK, Mitchell MW, Steinberg AM. Multiparticle state tomography: hidden differences. PHYSICAL REVIEW LETTERS 2007; 98:043601. [PMID: 17358765 DOI: 10.1103/physrevlett.98.043601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Indexed: 05/14/2023]
Abstract
We address the problem of completely characterizing multiparticle states including loss of information to unobserved degrees of freedom. In systems where nonclassical interference plays a role, such as linear-optics quantum gates, such information can degrade interference in two ways, by decoherence and by distinguishing the particles. Distinguishing information, often the limiting factor for quantum optical devices, is not correctly described by previous state-reconstruction techniques, which account only for decoherence. We extend these techniques and find that a single modified density matrix can completely describe partially coherent, partially distinguishable states. We use this observation to experimentally characterize two-photon polarization states in single-mode optical fiber.
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Affiliation(s)
- R B A Adamson
- Centre for Quantum Information and Quantum Control, Institute for Optical Sciences, Department of Physics, 60 St. George St., University of Toronto, Toronto, Ontario, Canada, M5S 1A7
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28
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Xiang GY, Huang YF, Sun FW, Zhang P, Ou ZY, Guo GC. Demonstration of temporal distinguishability in a four-photon state and a six-photon state. PHYSICAL REVIEW LETTERS 2006; 97:023604. [PMID: 16907443 DOI: 10.1103/physrevlett.97.023604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Indexed: 05/11/2023]
Abstract
An experiment is performed to demonstrate the temporal distinguishability of a four-photon state and a six-photon state, both from parametric down-conversion. The experiment is based on a multiphoton interference scheme in a recently discovered projection measurement of a maximally entangled N-photon state. By measuring the visibility of the interference dip, we can distinguish the various scenarios in the temporal distribution of the pairs and, thus, quantitatively determine the degree of temporal distinguishability of a multiphoton state.
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Affiliation(s)
- G Y Xiang
- Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, 230026, People's Republic of China
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29
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Okamoto R, Hofmann HF, Takeuchi S, Sasaki K. Demonstration of an optical quantum controlled-NOT gate without path interference. PHYSICAL REVIEW LETTERS 2005; 95:210506. [PMID: 16384126 DOI: 10.1103/physrevlett.95.210506] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Indexed: 05/05/2023]
Abstract
We report the first experimental demonstration of an optical quantum controlled-NOT gate without any path interference, where the two interacting path interferometers of the original proposals have been replaced by three partially polarizing beam splitters with suitable polarization dependent transmittance and reflectance. The performance of the device is evaluated using a recently proposed method, by which the quantum process fidelity and the entanglement capability can be estimated from the 32 measurement results of two classical truth tables, significantly less than the 256 measurement results required for full quantum tomography.
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Affiliation(s)
- Ryo Okamoto
- Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0812, Japan
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30
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Pryde GJ, O'Brien JL, White AG, Bartlett SD. Demonstrating superior discrimination of locally prepared states using nonlocal measurements. PHYSICAL REVIEW LETTERS 2005; 94:220406. [PMID: 16090373 DOI: 10.1103/physrevlett.94.220406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Indexed: 05/03/2023]
Abstract
We experimentally demonstrate the superior discrimination of separated, unentangled two-qubit correlated states using nonlocal measurements, when compared with measurements based on local operations and classical communications. When predicted theoretically, this phenomenon was dubbed "quantum nonlocality without entanglement." We characterize the performance of the nonlocal, or joint, measurement with a payoff function, for which we measure 0.72 +/- 0.02, compared with the maximum locally achievable value of 2/3 and the overall optimal value of 0.75.
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Affiliation(s)
- G J Pryde
- Centre for Quantum Computer Technology, Physics Department, The University of Queensland, Brisbane 4072, Australia
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31
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Kim YH, Grice WP. Measurement of the spectral properties of the two-photon state generated via type II spontaneous parametric downconversion. OPTICS LETTERS 2005; 30:908-10. [PMID: 15865395 DOI: 10.1364/ol.30.000908] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We report complete measurement of the spectral properties of photon pairs generated via spontaneous parametric downconversion. The measurements, which include not only single-photon spectra but also two-photon joint spectra, were performed for both cw and ultrafast-pumping configurations. In agreement with theoretical predictions, the spectra for the ultrafast-pumped case reveal asymmetries that are not present with cw pumping.
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Affiliation(s)
- Yoon-Ho Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 790-784, South Korea.
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32
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Koshino K, Ishihara H. Evaluation of two-photon nonlinearity by a semiclassical method. PHYSICAL REVIEW LETTERS 2004; 93:173601. [PMID: 15525076 DOI: 10.1103/physrevlett.93.173601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Indexed: 05/24/2023]
Abstract
In order to discuss the two-photon nonlinearity theoretically, both photons and nonlinear materials should be treated quantum mechanically, which usually is a heavy theoretical task. Contrarily, nonlinear optics for classical light has been developed well and a detailed analysis is possible for realistic complex nonlinear systems. Here we show that the two-photon nonlinearity can be evaluated from the linear and third-order nonlinear output fields against a classical input pulse, which contains 2(-1/2) photons on average.
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Affiliation(s)
- Kazuki Koshino
- CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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33
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Takeuchi S, Okamoto R, Sasaki K. High-yield single-photon source using gated spontaneous parametric downconversion. APPLIED OPTICS 2004; 43:5708-5711. [PMID: 15536662 DOI: 10.1364/ao.43.005708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The construction of a single-photon source by use of gated parametric fluorescence is reported with the measurement results of the photon number distribution. A beamlike twin-photon method is used in order to achieve high-collection efficiency. The estimated probability P(1) to find a single photon in a collimated output pulse is 26.5% at a repetition rate of 10 kHz when the effective quantum efficiency of 27.4% in the detection setup is compensated.
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Affiliation(s)
- Shigeki Takeuchi
- Research Institute for Electronic Science, Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-0812, Japan.
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34
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Pryde GJ, O'Brien JL, White AG, Bartlett SD, Ralph TC. Measuring a photonic qubit without destroying it. PHYSICAL REVIEW LETTERS 2004; 92:190402. [PMID: 15169391 DOI: 10.1103/physrevlett.92.190402] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Indexed: 05/24/2023]
Abstract
Measuring the polarization of a single photon typically results in its destruction. We propose, demonstrate, and completely characterize a quantum nondemolition (QND) scheme for realizing such a measurement nondestructively. This scheme uses only linear optics and photodetection of ancillary modes to induce a strong nonlinearity at the single-photon level, nondeterministically. We vary this QND measurement continuously into the weak regime and use it to perform a nondestructive test of complementarity in quantum mechanics. Our scheme realizes the most advanced general measurement of a qubit to date: it is nondestructive, can be made in any basis, and with arbitrary strength.
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Affiliation(s)
- G J Pryde
- Centre for Quantum Computer Technology, Department of Physics, University of Queensland, Brisbane 4072, Australia
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35
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Mitchell MW, Lundeen JS, Steinberg AM. Super-resolving phase measurements with a multiphoton entangled state. Nature 2004; 429:161-4. [PMID: 15141206 DOI: 10.1038/nature02493] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Accepted: 03/16/2004] [Indexed: 11/10/2022]
Abstract
Interference phenomena are ubiquitous in physics, often forming the basis of demanding measurements. Examples include Ramsey interferometry in atomic spectroscopy, X-ray diffraction in crystallography and optical interferometry in gravitational-wave studies. It has been known for some time that the quantum property of entanglement can be exploited to perform super-sensitive measurements, for example in optical interferometry or atomic spectroscopy. The idea has been demonstrated for an entangled state of two photons, but for larger numbers of particles it is difficult to create the necessary multiparticle entangled states. Here we demonstrate experimentally a technique for producing a maximally entangled three-photon state from initially non-entangled photons. The method can in principle be applied to generate states of arbitrary photon number, giving arbitrarily large improvement in measurement resolution. The method of state construction requires non-unitary operations, which we perform using post-selected linear-optics techniques similar to those used for linear-optics quantum computing.
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Affiliation(s)
- M W Mitchell
- Department of Physics, University of Toronto, 60 St George Street, Toronto, Ontario M5S 1A7, Canada.
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36
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O'Brien JL, Pryde GJ, White AG, Ralph TC, Branning D. Demonstration of an all-optical quantum controlled-NOT gate. Nature 2003; 426:264-7. [PMID: 14628045 DOI: 10.1038/nature02054] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2003] [Accepted: 09/16/2003] [Indexed: 11/09/2022]
Abstract
The promise of tremendous computational power, coupled with the development of robust error-correcting schemes, has fuelled extensive efforts to build a quantum computer. The requirements for realizing such a device are confounding: scalable quantum bits (two-level quantum systems, or qubits) that can be well isolated from the environment, but also initialized, measured and made to undergo controllable interactions to implement a universal set of quantum logic gates. The usual set consists of single qubit rotations and a controlled-NOT (CNOT) gate, which flips the state of a target qubit conditional on the control qubit being in the state 1. Here we report an unambiguous experimental demonstration and comprehensive characterization of quantum CNOT operation in an optical system. We produce all four entangled Bell states as a function of only the input qubits' logical values, for a single operating condition of the gate. The gate is probabilistic (the qubits are destroyed upon failure), but with the addition of linear optical quantum non-demolition measurements, it is equivalent to the CNOT gate required for scalable all-optical quantum computation.
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Affiliation(s)
- J L O'Brien
- Centre for Quantum Computer Technology, Department of Physics, University of Queensland, Brisbane 4072, Australia.
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37
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Bellini M, Marin F, Viciani S, Zavatta A, Arecchi FT. Nonlocal pulse shaping with entangled photon pairs. PHYSICAL REVIEW LETTERS 2003; 90:043602. [PMID: 12570422 DOI: 10.1103/physrevlett.90.043602] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2002] [Indexed: 05/23/2023]
Abstract
Nonlocal shaping effects in the time or spectral profiles of an entangled photon pair emerging from a pulsed parametric down-converter are observed by spectrally or temporally filtering one of the twin beams. In particular, we demonstrate the appearance of fourth-order ("ghost") interference fringes in the spectrum of one beam conditioned by photodetection at the output of an unbalanced Michelson interferometer placed in the path of the other beam. The coherence time of the pump is the limiting factor for the sharpness of the details in the shaped biphoton spectrum.
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Affiliation(s)
- M Bellini
- Istituto Nazionale di Ottica Applicata, Largo E. Fermi, 6, I-50125, Florence, Italy
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