1
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O'Reilly J, Toh G, Goetting I, Saha S, Shalaev M, Carter AL, Risinger A, Kalakuntla A, Li T, Verma A, Monroe C. Fast Photon-Mediated Entanglement of Continuously Cooled Trapped Ions for Quantum Networking. PHYSICAL REVIEW LETTERS 2024; 133:090802. [PMID: 39270187 DOI: 10.1103/physrevlett.133.090802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/30/2024] [Indexed: 09/15/2024]
Abstract
We entangle two cotrapped atomic barium ion qubits by collecting single visible photons from each ion through in vacuo 0.8 NA objectives, interfering them through an integrated fiber beam splitter and detecting them in coincidence. This projects the qubits into an entangled Bell state with an observed fidelity lower bound of F>94%. We also introduce an ytterbium ion for sympathetic cooling to remove the need for recooling interruptions and achieve a continuous entanglement rate of 250 s^{-1}.
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Affiliation(s)
| | - George Toh
- Duke Quantum Center, Departments of Electrical and Computer Engineering and Physics, Duke University, Durham, North Carolina 27708, USA
| | | | - Sagnik Saha
- Duke Quantum Center, Departments of Electrical and Computer Engineering and Physics, Duke University, Durham, North Carolina 27708, USA
| | - Mikhail Shalaev
- Duke Quantum Center, Departments of Electrical and Computer Engineering and Physics, Duke University, Durham, North Carolina 27708, USA
| | | | | | | | - Tingguang Li
- Duke Quantum Center, Departments of Electrical and Computer Engineering and Physics, Duke University, Durham, North Carolina 27708, USA
| | - Ashrit Verma
- Duke Quantum Center, Departments of Electrical and Computer Engineering and Physics, Duke University, Durham, North Carolina 27708, USA
| | - Christopher Monroe
- Duke Quantum Center, Departments of Electrical and Computer Engineering and Physics, Duke University, Durham, North Carolina 27708, USA
- Joint Quantum Institute, Departments of Physics and Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742, USA
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2
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Krutyanskiy V, Galli M, Krcmarsky V, Baier S, Fioretto DA, Pu Y, Mazloom A, Sekatski P, Canteri M, Teller M, Schupp J, Bate J, Meraner M, Sangouard N, Lanyon BP, Northup TE. Entanglement of Trapped-Ion Qubits Separated by 230 Meters. PHYSICAL REVIEW LETTERS 2023; 130:050803. [PMID: 36800448 DOI: 10.1103/physrevlett.130.050803] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 12/20/2022] [Indexed: 06/18/2023]
Abstract
We report on an elementary quantum network of two atomic ions separated by 230 m. The ions are trapped in different buildings and connected with 520(2) m of optical fiber. At each network node, the electronic state of an ion is entangled with the polarization state of a single cavity photon; subsequent to interference of the photons at a beam splitter, photon detection heralds entanglement between the two ions. Fidelities of up to (88.0+2.2-4.7)% are achieved with respect to a maximally entangled Bell state, with a success probability of 4×10^{-5}. We analyze the routes to improve these metrics, paving the way for long-distance networks of entangled quantum processors.
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Affiliation(s)
- V Krutyanskiy
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M Galli
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - V Krcmarsky
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - S Baier
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - D A Fioretto
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Y Pu
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - A Mazloom
- Department of Physics, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, USA
| | - P Sekatski
- Department of Applied Physics, University of Geneva, 1211 Geneva, Switzerland
| | - M Canteri
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M Teller
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - J Schupp
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - J Bate
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M Meraner
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - N Sangouard
- Institut de Physique Théorique, Université Paris-Saclay, CEA, CNRS, 91191 Gif-sur-Yvette, France
| | - B P Lanyon
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - T E Northup
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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3
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Koong ZX, Cygorek M, Scerri E, Santana TS, Park SI, Song JD, Gauger EM, Gerardot BD. Coherence in cooperative photon emission from indistinguishable quantum emitters. SCIENCE ADVANCES 2022; 8:eabm8171. [PMID: 35302855 PMCID: PMC8932659 DOI: 10.1126/sciadv.abm8171] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Photon-mediated interactions between atoms can arise via coupling to a common electromagnetic mode or by quantum interference. Here, we probe the role of coherence in cooperative emission arising from two distant but indistinguishable solid-state emitters because of path erasure. The primary signature of cooperative emission, the emergence of "bunching" at zero delay in an intensity correlation experiment, is used to characterize the indistinguishability of the emitters, their dephasing, and the degree of correlation in the joint system that can be coherently controlled. In a stark departure from a pair of uncorrelated emitters, in Hong-Ou-Mandel-type interference measurements, we observe photon statistics from a pair of indistinguishable emitters resembling that of a weak coherent state from an attenuated laser. Our experiments establish techniques to control and characterize cooperative behavior between matter qubits using the full quantum optics toolbox, a key step toward realizing large-scale quantum photonic networks.
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Affiliation(s)
- Zhe Xian Koong
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Moritz Cygorek
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Eleanor Scerri
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Ted S. Santana
- Centro de Cîencias Naturais e Humanas, Universidade Federal do ABC, Santo Andrè, São Paulo 09210-580, Brazil
| | - Suk In Park
- Center for Opto-Electronic Materials and Devices Research, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Jin Dong Song
- Center for Opto-Electronic Materials and Devices Research, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Erik M. Gauger
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Brian D. Gerardot
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
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4
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Wang XJ, Yang SJ, Sun PF, Jing B, Li J, Zhou MT, Bao XH, Pan JW. Cavity-Enhanced Atom-Photon Entanglement with Subsecond Lifetime. PHYSICAL REVIEW LETTERS 2021; 126:090501. [PMID: 33750156 DOI: 10.1103/physrevlett.126.090501] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/01/2021] [Indexed: 06/12/2023]
Abstract
A cold atomic ensemble suits well for optical quantum memories, and its entanglement with a single photon forms the building block for quantum networks that give promise for many revolutionary applications. Efficiency and lifetime are among the most important figures of merit for a memory. In this Letter, we report the realization of entanglement between an atomic ensemble and a single photon with subsecond lifetime and high efficiency. We engineer dual control modes in a ring cavity to create entanglement and make use of three-dimensional optical lattice to prolong memory lifetime. The memory efficiency is 38% for 0.1 s storage. We verify the atom-photon entanglement after 1 s storage by testing the Bell inequality with a result of S=2.36±0.14.
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Affiliation(s)
- Xu-Jie 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Sheng-Jun Yang
- 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Peng-Fei Sun
- 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bo Jing
- 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jun 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ming-Ti Zhou
- 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiao-Hui Bao
- 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 Center for Excellence 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 Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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5
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Stephenson LJ, Nadlinger DP, Nichol BC, An S, Drmota P, Ballance TG, Thirumalai K, Goodwin JF, Lucas DM, Ballance CJ. High-Rate, High-Fidelity Entanglement of Qubits Across an Elementary Quantum Network. PHYSICAL REVIEW LETTERS 2020; 124:110501. [PMID: 32242699 DOI: 10.1103/physrevlett.124.110501] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 02/06/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate remote entanglement of trapped-ion qubits via a quantum-optical fiber link with fidelity and rate approaching those of local operations. Two ^{88}Sr^{+} qubits are entangled via the polarization degree of freedom of two spontaneously emitted 422 nm photons which are coupled by high-numerical-aperture lenses into single-mode optical fibers and interfere on a beam splitter. A novel geometry allows high-efficiency photon collection while maintaining unit fidelity for ion-photon entanglement. We generate heralded Bell pairs with fidelity 94% at an average rate 182 s^{-1} (success probability 2.18×10^{-4}).
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Affiliation(s)
- L J Stephenson
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - D P Nadlinger
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - B C Nichol
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S An
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - P Drmota
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - T G Ballance
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - K Thirumalai
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - J F Goodwin
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - D M Lucas
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - C J Ballance
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
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6
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Entanglement of two quantum memories via fibres over dozens of kilometres. Nature 2020; 578:240-245. [PMID: 32051600 DOI: 10.1038/s41586-020-1976-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 11/12/2019] [Indexed: 11/08/2022]
Abstract
A quantum internet that connects remote quantum processors1,2 should enable a number of revolutionary applications such as distributed quantum computing. Its realization will rely on entanglement of remote quantum memories over long distances. Despite enormous progress3-12, at present the maximal physical separation achieved between two nodes is 1.3 kilometres10, and challenges for longer distances remain. Here we demonstrate entanglement of two atomic ensembles in one laboratory via photon transmission through city-scale optical fibres. The atomic ensembles function as quantum memories that store quantum states. We use cavity enhancement to efficiently create atom-photon entanglement13-15 and we use quantum frequency conversion16 to shift the atomic wavelength to telecommunications wavelengths. We realize entanglement over 22 kilometres of field-deployed fibres via two-photon interference17,18 and entanglement over 50 kilometres of coiled fibres via single-photon interference19. Our experiment could be extended to nodes physically separated by similar distances, which would thus form a functional segment of the atomic quantum network, paving the way towards establishing atomic entanglement over many nodes and over much longer distances.
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7
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Craddock AN, Hannegan J, Ornelas-Huerta DP, Siverns JD, Hachtel AJ, Goldschmidt EA, Porto JV, Quraishi Q, Rolston SL. Quantum Interference between Photons from an Atomic Ensemble and a Remote Atomic Ion. PHYSICAL REVIEW LETTERS 2019; 123:213601. [PMID: 31809132 DOI: 10.1103/physrevlett.123.213601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Indexed: 06/10/2023]
Abstract
Many remote-entanglement protocols rely on the generation and interference of photons produced by nodes within a quantum network. Quantum networks based on heterogeneous nodes provide a versatile platform by utilizing the complementary strengths of the differing systems. Implementation of such networks is challenging, due to the disparate spectral and temporal characteristics of the photons generated by the different quantum systems. Here, we report on the observation of quantum interference between photons generated from a single ion and an atomic ensemble. The photons are produced on demand by each source located in separate buildings, in a manner suitable for quantum networking. Given these results, we analyze the feasibility of hybrid ion-ensemble remote entanglement generation.
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Affiliation(s)
- A N Craddock
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
| | - J Hannegan
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
| | - D P Ornelas-Huerta
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
| | - J D Siverns
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
| | - A J Hachtel
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
| | - E A Goldschmidt
- Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
| | - J V Porto
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
| | - Q Quraishi
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
- Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
| | - S L Rolston
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA
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8
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Crocker C, Lichtman M, Sosnova K, Carter A, Scarano S, Monroe C. High purity single photons entangled with an atomic qubit. OPTICS EXPRESS 2019; 27:28143-28149. [PMID: 31684572 DOI: 10.1364/oe.27.028143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Trapped atomic ions are an ideal candidate for quantum network nodes, with long-lived identical qubit memories that can be locally entangled through their Coulomb interaction and remotely entangled through photonic channels. The integrity of this photonic interface is generally reliant on the purity of single photons produced by the quantum memory. Here, we demonstrate a single-photon source for quantum networking based on a trapped 138Ba+ ion with a single photon purity of g (2)(0)=(8.1±2.3)×10-5 without background subtraction. We further optimize the tradeoff between the photonic generation rate and the memory-photon entanglement fidelity for the case of polarization photonic qubits by tailoring the spatial mode of the collected light.
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9
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Cao Y, Li YH, Zou WJ, Li ZP, Shen Q, Liao SK, Ren JG, Yin J, Chen YA, Peng CZ, Pan JW. Bell Test over Extremely High-Loss Channels: Towards Distributing Entangled Photon Pairs between Earth and the Moon. PHYSICAL REVIEW LETTERS 2018; 120:140405. [PMID: 29694138 DOI: 10.1103/physrevlett.120.140405] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 02/12/2018] [Indexed: 06/08/2023]
Abstract
Quantum entanglement was termed "spooky action at a distance" in the well-known paper by Einstein, Podolsky, and Rosen. Entanglement is expected to be distributed over longer and longer distances in both practical applications and fundamental research into the principles of nature. Here, we present a proposal for distributing entangled photon pairs between Earth and the Moon using a Lagrangian point at a distance of 1.28 light seconds. One of the most fascinating features in this long-distance distribution of entanglement is as follows. One can perform the Bell test with human supplying the random measurement settings and recording the results while still maintaining spacelike intervals. To realize a proof-of-principle experiment, we develop an entangled photon source with 1 GHz generation rate, about 2 orders of magnitude higher than previous results. Violation of Bell's inequality was observed under a total simulated loss of 103 dB with measurement settings chosen by two experimenters. This demonstrates the feasibility of such long-distance Bell test over extremely high-loss channels, paving the way for one of the ultimate tests of the foundations of quantum mechanics.
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Affiliation(s)
- Yuan Cao
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Yu-Huai Li
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Wen-Jie Zou
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Zheng-Ping Li
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Qi Shen
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Sheng-Kai Liao
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Ji-Gang Ren
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Juan Yin
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Yu-Ao Chen
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Cheng-Zhi Peng
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Jian-Wei Pan
- National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
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10
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Generation of steady entanglement via unilateral qubit driving in bad cavities. Sci Rep 2017; 7:17648. [PMID: 29247250 PMCID: PMC5732200 DOI: 10.1038/s41598-017-17933-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 11/28/2017] [Indexed: 11/08/2022] Open
Abstract
We propose a scheme for generating an entangled state for two atoms trapped in two separate cavities coupled to each other. The scheme is based on the competition between the unitary dynamics induced by the classical fields and the collective decays induced by the dissipation of two non-local bosonic modes. In this scheme, only one qubit is driven by external classical fields, whereas the other need not be manipulated via classical driving. This is meaningful for experimental implementation between separate nodes of a quantum network. The steady entanglement can be obtained regardless of the initial state, and the robustness of the scheme against parameter fluctuations is numerically demonstrated. We also give an analytical derivation of the stationary fidelity to enable a discussion of the validity of this regime. Furthermore, based on the dissipative entanglement preparation scheme, we construct a quantum state transfer setup with multiple nodes as a practical application.
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11
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Liu SL, Liu SK, Li YH, Shi S, Zhou ZY, Shi BS. Coherent frequency bridge between visible and telecommunications band for vortex light. OPTICS EXPRESS 2017; 25:24290-24298. [PMID: 29041374 DOI: 10.1364/oe.25.024290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/17/2017] [Indexed: 06/07/2023]
Abstract
In quantum communications, vortex photons can encode higher-dimensional quantum states and build high-dimensional communication networks (HDCNs). The interfaces that connect different wavelengths are significant in HDCNs. We construct a coherent orbital angular momentum (OAM) frequency bridge via difference frequency conversion in a nonlinear bulk crystal for HDCNs. Using a single resonant cavity, maximum quantum conversion efficiencies from visible to infrared are 36%, 15%, and 7.8% for topological charges of 0,1, and 2, respectively. The average fidelity obtained using quantum state tomography for the down-converted infrared OAM-state of topological charge 1 is 96.51%. We also prove that the OAM is conserved in this process by measuring visible and infrared interference patterns. This coherent OAM frequency-down conversion bridge represents a basis for an interface between two high-dimensional quantum systems operating with different spectra.
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12
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Abstract
The concept of randomness plays an important part in many disciplines. On the one hand, the question of whether random processes exist is fundamental for our understanding of nature. On the other, randomness is a resource for cryptography, algorithms and simulations. Standard methods for generating randomness rely on assumptions about the devices that are often not valid in practice. However, quantum technologies enable new methods for generating certified randomness, based on the violation of Bell inequalities. These methods are referred to as device-independent because they do not rely on any modelling of the devices. Here we review efforts to design device-independent randomness generators and the associated challenges.
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13
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Siverns JD, Li X, Quraishi Q. Ion-photon entanglement and quantum frequency conversion with trapped Ba + ions. APPLIED OPTICS 2017; 56:B222-B230. [PMID: 28157932 DOI: 10.1364/ao.56.00b222] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Trapped ions are excellent candidates for quantum nodes, as they possess many desirable features of a network node including long lifetimes, on-site processing capability, and production of photonic flying qubits. However, unlike classical networks in which data may be transmitted in optical fibers and where the range of communication is readily extended with amplifiers, quantum systems often emit photons that have a limited propagation range in optical fibers and, by virtue of the nature of a quantum state, cannot be noiselessly amplified. Here, we first describe a method to extract flying qubits from a Ba+ trapped ion via shelving to a long-lived, low-lying D-state with higher entanglement probabilities compared with current strong and weak excitation methods. We show a projected fidelity of ≈89% of the ion-photon entanglement. We compare several methods of ion-photon entanglement generation, and we show how the fidelity and entanglement probability varies as a function of the photon collection optic's numerical aperture. We then outline an approach for quantum frequency conversion of the photons emitted by the Ba+ ion to the telecommunication range for long-distance networking and to 780 nm for potential entanglement with rubidium-based quantum memories. Our approach is significant for extending the range of quantum networks and for the development of hybrid quantum networks compromised of different types of quantum memories.
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14
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Jin Z, Su SL, Zhu AD, Wang HF, Zhang S. Dissipative preparation of distributed steady entanglement: an approach of unilateral qubit driving. OPTICS EXPRESS 2017; 25:88-101. [PMID: 28085813 DOI: 10.1364/oe.25.000088] [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 propose a nonlocal scheme for preparing a distributed steady-state entanglement of two atoms trapped in separate optical cavities coupled through an optical fiber based on the combined effect of the unitary dynamics and dissipative process. In this scheme, only the qubit of one node is driven by an external classical field, while the other one does not need to be manipulated by an external field. This is meaningful for long distance quantum information processing tasks, and the experimental implementation is greatly simplified due to the unilateral manipulation on one node and the process of entanglement distribution can be avoided. This guarantees the absolute security of long distance quantum information processing tasks and makes the scheme more robust than that based on the unitary dynamics. We introduce the purity to characterize the mixture degree of the target steady-state. The steady entanglement can be obtained independent of the initial state. Furthermore, based on the dissipative entanglement preparation scheme, we construct a quantum teleportation setup with multiple nodes as a practical application, and the numerical simulation demonstrates the scheme can be realized effectively under the current experimental conditions..
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15
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Mahmoodian S, Lodahl P, Sørensen AS. Quantum Networks with Chiral-Light-Matter Interaction in Waveguides. PHYSICAL REVIEW LETTERS 2016; 117:240501. [PMID: 28009207 DOI: 10.1103/physrevlett.117.240501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Indexed: 06/06/2023]
Abstract
We propose a scalable architecture for a quantum network based on a simple on-chip photonic circuit that performs loss-tolerant two-qubit measurements. The circuit consists of two quantum emitters positioned in the arms of an on-chip Mach-Zehnder interferometer composed of waveguides with chiral-light-matter interfaces. The efficient chiral-light-matter interaction allows the emitters to perform high-fidelity intranode two-qubit parity measurements within a single chip and to emit photons to generate internode entanglement, without any need for reconfiguration. We show that, by connecting multiple circuits of this kind into a quantum network, it is possible to perform universal quantum computation with heralded two-qubit gate fidelities F∼0.998 achievable in state-of-the-art quantum dot systems.
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Affiliation(s)
- Sahand Mahmoodian
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
| | - Peter Lodahl
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
| | - Anders S Sørensen
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
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16
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Ekimov EA, Kondrin MV. Vacancy-impurity centers in diamond: perspectives of synthesis and applications. ACTA ACUST UNITED AC 2016. [DOI: 10.3367/ufnr.2016.11.037959] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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17
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Ulanov AE, Fedorov IA, Sychev D, Grangier P, Lvovsky AI. Loss-tolerant state engineering for quantum-enhanced metrology via the reverse Hong-Ou-Mandel effect. Nat Commun 2016; 7:11925. [PMID: 27324115 PMCID: PMC4919515 DOI: 10.1038/ncomms11925] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/11/2016] [Indexed: 11/10/2022] Open
Abstract
Highly entangled quantum states, shared by remote parties, are vital for quantum communications and metrology. Particularly promising are the N00N states-entangled N-photon wavepackets delocalized between two different locations-which outperform coherent states in measurement sensitivity. However, these states are notoriously vulnerable to losses, making them difficult to both share them between remote locations and recombine in order to exploit interference effects. Here we address this challenge by utilizing the reverse Hong-Ou-Mandel effect to prepare a high-fidelity two-photon N00N state shared between two parties connected by a lossy optical medium. We measure the prepared state by two-mode homodyne tomography, thereby demonstrating that the enhanced phase sensitivity can be exploited without recombining the two parts of the N00N state. Finally, we demonstrate the application of our method to remotely prepare superpositions of coherent states, known as Schrödinger's cat states.
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Affiliation(s)
- Alexander E Ulanov
- Russian Quantum Center, 100 Novaya Street, Skolkovo, Moscow 143025, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
| | - Ilya A Fedorov
- Russian Quantum Center, 100 Novaya Street, Skolkovo, Moscow 143025, Russia.,P.N. Lebedev Physics Institute, Leninskiy prospect 53, Moscow 119991, Russia
| | - Demid Sychev
- Russian Quantum Center, 100 Novaya Street, Skolkovo, Moscow 143025, Russia
| | - Philippe Grangier
- Laboratoire Charles Fabry, Institut d'Optique Graduate School, CNRS, Université Paris-Saclay, Palaiseau 91127, France
| | - A I Lvovsky
- Russian Quantum Center, 100 Novaya Street, Skolkovo, Moscow 143025, Russia.,P.N. Lebedev Physics Institute, Leninskiy prospect 53, Moscow 119991, Russia.,Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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18
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Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres. Nature 2015; 526:682-6. [DOI: 10.1038/nature15759] [Citation(s) in RCA: 1349] [Impact Index Per Article: 149.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/28/2015] [Indexed: 11/09/2022]
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19
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Kurz C, Schug M, Eich P, Huwer J, Müller P, Eschner J. Experimental protocol for high-fidelity heralded photon-to-atom quantum state transfer. Nat Commun 2014; 5:5527. [DOI: 10.1038/ncomms6527] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 10/10/2014] [Indexed: 11/09/2022] Open
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20
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Abstract
Diamond-based quantum teleportation works every time
[Also see Research Article by
Pfaff
et al.
]
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Affiliation(s)
- Mete Atatüre
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - John J. L. Morton
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
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21
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Noek R, Vrijsen G, Gaultney D, Mount E, Kim T, Maunz P, Kim J. High speed, high fidelity detection of an atomic hyperfine qubit. OPTICS LETTERS 2013; 38:4735-4738. [PMID: 24322119 DOI: 10.1364/ol.38.004735] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Fast and efficient detection of the qubit state in trapped ion systems is critical for implementing quantum error correction and performing fundamental tests such as a loophole-free Bell test. In this work we present a simple qubit state detection protocol for a (171)Yb+ hyperfine atomic qubit trapped in a microfabricated surface trap, enabled by high collection efficiency of the scattered photons and low background photon count rate. We demonstrate average detection times of 10.5, 28.1, and 99.8 μs, corresponding to state detection fidelities of 99%, 99.856(8)%, and 99.915(7)%, respectively.
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22
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Hofer SG, Vasilyev DV, Aspelmeyer M, Hammerer K. Time-continuous Bell measurements. PHYSICAL REVIEW LETTERS 2013; 111:170404. [PMID: 24206465 DOI: 10.1103/physrevlett.111.170404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Indexed: 06/02/2023]
Abstract
We combine the concept of Bell measurements, in which two systems are projected into a maximally entangled state, with the concept of continuous measurements, which concerns the evolution of a continuously monitored quantum system. For such time-continuous Bell measurements we derive the corresponding stochastic Schrödinger equations, as well as the unconditional feedback master equations. Our results apply to a wide range of physical systems, and are easily adapted to describe an arbitrary number of systems and measurements. Time-continuous Bell measurements therefore provide a versatile tool for the control of complex quantum systems and networks. As examples we show that (i) two two-level systems can be deterministically entangled via homodyne detection, tolerating photon loss up to 50%, and (ii) a quantum state of light can be continuously teleported to a mechanical oscillator, which works under the same conditions as are required for optomechanical ground-state cooling.
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Affiliation(s)
- Sebastian G Hofer
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria and Institute for Theoretical Physics, Institute for Gravitational Physics (Albert Einstein Institute), Leibniz University Hannover, Callinstraße 38, 30167 Hannover, Germany
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23
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24
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Slodička L, Hétet G, Röck N, Schindler P, Hennrich M, Blatt R. Atom-atom entanglement by single-photon detection. PHYSICAL REVIEW LETTERS 2013; 110:083603. [PMID: 23473144 DOI: 10.1103/physrevlett.110.083603] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Indexed: 06/01/2023]
Abstract
A scheme for entangling distant atoms is realized, as proposed in the seminal paper by [C. Cabrillo et al., Phys. Rev. A 59, 1025 (1999)]. The protocol is based on quantum interference and detection of a single photon scattered from two effectively one meter distant laser cooled and trapped atomic ions. The detection of a single photon heralds entanglement of two internal states of the trapped ions with high rate and with a fidelity limited mostly by atomic motion. Control of the entangled state phase is demonstrated by changing the path length of the single-photon interferometer.
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Affiliation(s)
- L Slodička
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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25
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Hofmann J, Krug M, Ortegel N, Gérard L, Weber M, Rosenfeld W, Weinfurter H. Heralded entanglement between widely separated atoms. Science 2012; 337:72-5. [PMID: 22767924 DOI: 10.1126/science.1221856] [Citation(s) in RCA: 293] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Entanglement is the essential feature of quantum mechanics. Notably, observers of two or more entangled particles will find correlations in their measurement results that cannot be explained by classical statistics. To make it a useful resource, particularly for scalable long-distance quantum communication, the heralded generation of entanglement between distant massive quantum systems is necessary. We report on the creation and analysis of heralded entanglement between spins of two single rubidium-87 atoms trapped independently 20 meters apart. Our results illustrate the viability of an integral resource for quantum information science, as well as for fundamental tests of quantum mechanics.
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Affiliation(s)
- Julian Hofmann
- Fakultät für Physik, Ludwig-Maximilians-Universität München, München, Germany
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26
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Bernien H, Childress L, Robledo L, Markham M, Twitchen D, Hanson R. Two-photon quantum interference from separate nitrogen vacancy centers in diamond. PHYSICAL REVIEW LETTERS 2012; 108:043604. [PMID: 22400844 DOI: 10.1103/physrevlett.108.043604] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Indexed: 05/05/2023]
Abstract
We report on the observation of quantum interference of the emission from two separate nitrogen vacancy (NV) centers in diamond. Taking advantage of optically induced spin polarization in combination with polarization filtering, we isolate a single transition within the zero-phonon line of the nonresonantly excited NV centers. The time-resolved two-photon interference contrast of this filtered emission reaches 66%. Furthermore, we observe quantum interference from dissimilar NV centers tuned into resonance through the dc Stark effect. These results pave the way towards measurement-based entanglement between remote NV centers and the realization of quantum networks with solid-state spins.
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Affiliation(s)
- Hannes Bernien
- Kavli Institute of Nanoscience Delft, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
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27
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28
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Abstract
Bell's theorem shows that local realistic theories place strong restrictions on observable correlations between different systems, giving rise to Bell's inequality which can be violated in experiments using entangled quantum states. Bell's theorem is based on the assumptions of realism, locality, and the freedom to choose between measurement settings. In experimental tests, "loopholes" arise which allow observed violations to still be explained by local realistic theories. Violating Bell's inequality while simultaneously closing all such loopholes is one of the most significant still open challenges in fundamental physics today. In this paper, we present an experiment that violates Bell's inequality while simultaneously closing the locality loophole and addressing the freedom-of-choice loophole, also closing the latter within a reasonable set of assumptions. We also explain that the locality and freedom-of-choice loopholes can be closed only within nondeterminism, i.e., in the context of stochastic local realism.
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29
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Deng DL, Wu C, Chen JL, Oh CH. Fault-tolerant Greenberger-Horne-Zeilinger paradox based on non-Abelian anyons. PHYSICAL REVIEW LETTERS 2010; 105:060402. [PMID: 20867962 DOI: 10.1103/physrevlett.105.060402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Indexed: 05/29/2023]
Abstract
We propose a scheme to test the Greenberger-Horne-Zeilinger paradox based on braidings of non-Abelian anyons, which are exotic quasiparticle excitations of topological states of matter. Because topological ordered states are robust against local perturbations, this scheme is in some sense "fault-tolerant" and might close the detection inefficiency loophole problem in previous experimental tests of the Greenberger-Horne-Zeilinger paradox. In turn, the construction of the Greenberger-Horne-Zeilinger paradox reveals the nonlocal property of non-Abelian anyons. Our results indicate that the non-Abelian fractional statistics is a pure quantum effect and cannot be described by local realistic theories. Finally, we present a possible experimental implementation of the scheme based on the anyonic interferometry technologies.
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Affiliation(s)
- Dong-Ling Deng
- Theoretical Physics Division, Chern Institute of Mathematics, Nankai University, Tianjin 300071, People's Republic of China
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30
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Vértesi T, Pironio S, Brunner N. Closing the detection loophole in Bell experiments using qudits. PHYSICAL REVIEW LETTERS 2010; 104:060401. [PMID: 20366808 DOI: 10.1103/physrevlett.104.060401] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Indexed: 05/29/2023]
Abstract
We show that the detection efficiencies required for closing the detection loophole in Bell tests can be significantly lowered using quantum systems of dimension larger than two. We introduce a series of asymmetric Bell tests for which an efficiency arbitrarily close to 1/N can be tolerated using N-dimensional systems, and a symmetric Bell test for which the efficiency can be lowered down to 61.8% using four-dimensional systems. Experimental perspectives for our schemes look promising considering recent progress in atom-photon entanglement and in photon hyperentanglement.
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Affiliation(s)
- Tamás Vértesi
- Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary
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31
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Almendros M, Huwer J, Piro N, Rohde F, Schuck C, Hennrich M, Dubin F, Eschner J. Bandwidth-tunable single-photon source in an ion-trap quantum network. PHYSICAL REVIEW LETTERS 2009; 103:213601. [PMID: 20366035 DOI: 10.1103/physrevlett.103.213601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Indexed: 05/29/2023]
Abstract
We report a tunable single-photon source based on a single trapped ion. Employing spontaneous Raman scattering and in-vacuum optics with large numerical aperture, single photons are efficiently created with controlled temporal shape and coherence time. These can be varied between 70 ns and 1.6 micros, as characterized by operating two sources simultaneously in two remote ion traps which reveals mutual and individual coherence through two-photon interference.
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Affiliation(s)
- M Almendros
- ICFO-Institut de Ciències Fotòniques, Mediterranean Technology Park, E-08860 Castelldefels, Barcelona, Spain
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32
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Sanaka K, Pawlis A, Ladd TD, Lischka K, Yamamoto Y. Indistinguishable photons from independent semiconductor nanostructures. PHYSICAL REVIEW LETTERS 2009; 103:053601. [PMID: 19792497 DOI: 10.1103/physrevlett.103.053601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Indexed: 05/28/2023]
Abstract
We demonstrate quantum interference between photons generated by the radiative decay processes of excitons that are bound to isolated fluorine donor impurities in ZnSe/ZnMgSe quantum-well nanostructures. The ability to generate single photons from these devices is confirmed by autocorrelation experiments, and the indistinguishability of photons emitted from two independent nanostructures is confirmed via a Hong-Ou-Mandel dip. These results indicate that donor impurities in appropriately engineered semiconductor structures can portray atomlike homogeneity and coherence properties, potentially enabling scalable technologies for future large-scale optical quantum computers and quantum communication networks.
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Affiliation(s)
- Kaoru Sanaka
- Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305-4088, USA.
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33
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Maunz P, Olmschenk S, Hayes D, Matsukevich DN, Duan LM, Monroe C. Heralded quantum gate between remote quantum memories. PHYSICAL REVIEW LETTERS 2009; 102:250502. [PMID: 19659062 DOI: 10.1103/physrevlett.102.250502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Indexed: 05/28/2023]
Abstract
We demonstrate a probabilistic entangling quantum gate between two distant trapped ytterbium ions. The gate is implemented between the hyperfine "clock" state atomic qubits and mediated by the interference of two emitted photons carrying frequency encoded qubits. Heralded by the coincidence detection of these two photons, the gate has an average output state fidelity of 89+/-2%. This entangling gate together with single qubit operations is sufficient to generate large entangled cluster states for scalable quantum computing.
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Affiliation(s)
- P Maunz
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA.
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34
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Olmschenk S, Matsukevich DN, Maunz P, Hayes D, Duan LM, Monroe C. Quantum Teleportation Between Distant Matter Qubits. Science 2009; 323:486-9. [DOI: 10.1126/science.1167209] [Citation(s) in RCA: 340] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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35
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Rosenfeld W, Hocke F, Henkel F, Krug M, Volz J, Weber M, Weinfurter H. Towards long-distance atom-photon entanglement. PHYSICAL REVIEW LETTERS 2008; 101:260403. [PMID: 19437626 DOI: 10.1103/physrevlett.101.260403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report the observation of entanglement between a single trapped atom and a single photon at remote locations. The degree of coherence of the entangled atom-photon pair is verified via appropriate local correlation measurements, after communicating the photon via an optical fiber link of 300 m length to a receiver 3.5 m apart. In addition, we measured the temporal evolution of the atomic density matrix after projecting the atom via a state measurement of the photon onto several well-defined spin states. We find that the state of the single atom dephases on a time scale of 150 micros, which represents an important step towards long-distance quantum networking with individual neutral atoms.
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Affiliation(s)
- W Rosenfeld
- Fakultät für Physik, Ludwig-Maximilians-Universität München, D-80799 München, Germany
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36
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Campbell ET, Benjamin SC. Measurement-based entanglement under conditions of extreme photon loss. PHYSICAL REVIEW LETTERS 2008; 101:130502. [PMID: 18851427 DOI: 10.1103/physrevlett.101.130502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Indexed: 05/26/2023]
Abstract
The act of measuring optical emissions from two remote qubits can entangle them. By demanding that a photon from each qubit reaches the detectors, one can ensure that no photon was lost. But retaining both photons is rare when loss rates are high, as in Moehring et al. where 30 successes occurred per 10(9) attempts. We describe a means to exploit the low grade entanglement heralded by the detection of a lone photon: A subsequent perfect operation is quickly achieved by consuming this noisy resource. We require only two qubits per node, and can tolerate both path length variation and loss asymmetry. The impact of photon loss upon the failure rate is then linear; realistic high-loss devices can gain orders of magnitude in performance and thus support quantum computing.
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Affiliation(s)
- Earl T Campbell
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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37
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Matsukevich DN, Maunz P, Moehring DL, Olmschenk S, Monroe C. Bell inequality violation with two remote atomic qubits. PHYSICAL REVIEW LETTERS 2008; 100:150404. [PMID: 18518088 DOI: 10.1103/physrevlett.100.150404] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Indexed: 05/26/2023]
Abstract
We observe violation of a Bell inequality between the quantum states of two remote Yb+ ions separated by a distance of about 1 m with the detection loophole closed. The heralded entanglement of two ions is established via interference and joint detection of two emitted photons, whose polarization is entangled with each ion. The entanglement of remote qubits is also characterized by full quantum state tomography.
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Affiliation(s)
- D N Matsukevich
- Department of Physics and Joint Quantum Institute, University of Maryland, College Park, MD 20742, USA.
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38
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Thiel C, von Zanthier J, Bastin T, Solano E, Agarwal GS. Generation of symmetric Dicke states of remote qubits with linear optics. PHYSICAL REVIEW LETTERS 2007; 99:193602. [PMID: 18233076 DOI: 10.1103/physrevlett.99.193602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Indexed: 05/25/2023]
Abstract
We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit states.
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Affiliation(s)
- C Thiel
- Institut für Optik, Information und Photonik, Max-Planck Forschungsgruppe, Universität Erlangen-Nürnberg, 91058, Erlangen, Germany.
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39
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Dubin F, Rotter D, Mukherjee M, Gerber S, Blatt R. Single-ion two-photon source. PHYSICAL REVIEW LETTERS 2007; 99:183001. [PMID: 17995402 DOI: 10.1103/physrevlett.99.183001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Indexed: 05/25/2023]
Abstract
A single trapped ion is converted into a pseudo-two-photon source by splitting its resonance fluorescence, delaying part of it and by recombining both parts on a beam splitter. A destructive two-photon interference is observed with a contrast reaching 83(5)%. The spectral brightness of our two-photon source is quantified and shown to be comparable to parametric down-conversion devices.
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Affiliation(s)
- F Dubin
- Institute for Experimental Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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40
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Moehring DL, Maunz P, Olmschenk S, Younge KC, Matsukevich DN, Duan LM, Monroe C. Entanglement of single-atom quantum bits at a distance. Nature 2007; 449:68-71. [PMID: 17805290 DOI: 10.1038/nature06118] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Accepted: 07/14/2007] [Indexed: 11/09/2022]
Abstract
Quantum information science involves the storage, manipulation and communication of information encoded in quantum systems, where the phenomena of superposition and entanglement can provide enhancements over what is possible classically. Large-scale quantum information processors require stable and addressable quantum memories, usually in the form of fixed quantum bits (qubits), and a means of transferring and entangling the quantum information between memories that may be separated by macroscopic or even geographic distances. Atomic systems are excellent quantum memories, because appropriate internal electronic states can coherently store qubits over very long timescales. Photons, on the other hand, are the natural platform for the distribution of quantum information between remote qubits, given their ability to traverse large distances with little perturbation. Recently, there has been considerable progress in coupling small samples of atomic gases through photonic channels, including the entanglement between light and atoms and the observation of entanglement signatures between remotely located atomic ensembles. In contrast to atomic ensembles, single-atom quantum memories allow the implementation of conditional quantum gates through photonic channels, a key requirement for quantum computing. Along these lines, individual atoms have been coupled to photons in cavities, and trapped atoms have been linked to emitted photons in free space. Here we demonstrate the entanglement of two fixed single-atom quantum memories separated by one metre. Two remotely located trapped atomic ions each emit a single photon, and the interference and detection of these photons signals the entanglement of the atomic qubits. We characterize the entangled pair by directly measuring qubit correlations with near-perfect detection efficiency. Although this entanglement method is probabilistic, it is still in principle useful for subsequent quantum operations and scalable quantum information applications.
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Affiliation(s)
- D L Moehring
- FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA.
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41
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Zhao B, Chen ZB, Chen YA, Schmiedmayer J, Pan JW. Robust creation of entanglement between remote memory qubits. PHYSICAL REVIEW LETTERS 2007; 98:240502. [PMID: 17677950 DOI: 10.1103/physrevlett.98.240502] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Indexed: 05/16/2023]
Abstract
In this Letter we propose a robust quantum repeater architecture building on the original Duan-Lukin-Cirac-Zoller (DLCZ) protocol [L.-M. Duan, M. D. Lukin, J. I. Cirac, and P. Zoller, Nature (London) 414, 413 (2001)10.1038/35106500]. The architecture is based on two-photon Hong-Ou-Mandel-type interference which relaxes the long-distance stability requirements by about 7 orders of magnitude, from subwavelength for the single photon interference required by DLCZ to the coherence length of the photons. Our proposal provides an exciting possibility for robust and realistic long-distance quantum communication.
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Affiliation(s)
- Bo Zhao
- Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, D-69120 Heidelberg, Germany
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42
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Cabello A, Larsson JA. Minimum detection efficiency for a loophole-free atom-photon bell experiment. PHYSICAL REVIEW LETTERS 2007; 98:220402. [PMID: 17677821 DOI: 10.1103/physrevlett.98.220402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Indexed: 05/16/2023]
Abstract
In Bell experiments, one problem is to achieve high enough photodetection to ensure that there is no possibility of describing the results via a local hidden-variable model. Using the Clauser-Horne inequality and a two-photon nonmaximally entangled state, a photodetection efficiency higher than 0.67 is necessary. Here we discuss atom-photon Bell experiments. We show that, assuming perfect detection efficiency of the atom, it is possible to perform a loophole-free atom-photon Bell experiment whenever the photodetection efficiency exceeds 0.50.
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Affiliation(s)
- Adán Cabello
- Departamento de Física Aplicada II, Universidad de Sevilla, E-41012 Sevilla, Spain.
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43
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Brunner N, Gisin N, Scarani V, Simon C. Detection loophole in asymmetric bell experiments. PHYSICAL REVIEW LETTERS 2007; 98:220403. [PMID: 17677822 DOI: 10.1103/physrevlett.98.220403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Indexed: 05/16/2023]
Abstract
The problem of closing the detection loophole with asymmetric systems, such as entangled atom-photon pairs, is addressed. We show that, for the Bell inequality I3322, a minimal detection efficiency of 43% can be tolerated for one of the particles, if the other one is always detected. We also study the influence of noise and discuss the prospects of experimental implementation.
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Affiliation(s)
- Nicolas Brunner
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
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44
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Chanelière T, Matsukevich DN, Jenkins SD, Lan SY, Zhao R, Kennedy TAB, Kuzmich A. Quantum interference of electromagnetic fields from remote quantum memories. PHYSICAL REVIEW LETTERS 2007; 98:113602. [PMID: 17501054 DOI: 10.1103/physrevlett.98.113602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Indexed: 05/15/2023]
Abstract
We observe quantum, Hong-Ou-Mandel, interference of fields produced by two remote atomic memories. High-visibility interference is obtained by utilizing the finite atomic memory time in four-photon delayed coincidence measurements. Interference of fields from remote atomic memories is a crucial element in protocols for scalable entanglement distribution.
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Affiliation(s)
- T Chanelière
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA
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45
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Cabello A. Bipartite bell inequalities for hyperentangled states. PHYSICAL REVIEW LETTERS 2006; 97:140406. [PMID: 17155227 DOI: 10.1103/physrevlett.97.140406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Indexed: 05/12/2023]
Abstract
We show that bipartite Bell inequalities based on the Einstein-Podolsky-Rosen criterion for elements of reality and derived from the properties of some hyperentangled states allow feasible experimental verification of the fact that quantum nonlocality grows exponentially with the size of the subsystems, and Bell loophole-free tests with currently available photodetection efficiencies.
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Affiliation(s)
- Adán Cabello
- Departamento de Física Aplicada II, Universidad de Sevilla, 41012 Sevilla, Spain.
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46
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Madsen MJ, Moehring DL, Maunz P, Kohn RN, Duan LM, Monroe C. Ultrafast coherent excitation of a trapped ion qubit for fast gates and photon frequency qubits. PHYSICAL REVIEW LETTERS 2006; 97:040505. [PMID: 16907559 DOI: 10.1103/physrevlett.97.040505] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Indexed: 05/11/2023]
Abstract
We demonstrate ultrafast coherent excitation of an atomic qubit stored in the hyperfine levels of a single trapped cadmium ion. Such ultrafast excitation is crucial for entangling networks of remotely located trapped ions through the interference of photon frequency qubits, and is also a key component for realizing ultrafast quantum gates between Coulomb-coupled ions.
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Affiliation(s)
- M J Madsen
- FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA.
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47
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Beugnon J, Jones MPA, Dingjan J, Darquié B, Messin G, Browaeys A, Grangier P. Quantum interference between two single photons emitted by independently trapped atoms. Nature 2006; 440:779-82. [PMID: 16598253 DOI: 10.1038/nature04628] [Citation(s) in RCA: 241] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 01/31/2006] [Indexed: 11/08/2022]
Abstract
When two indistinguishable single photons are fed into the two input ports of a beam splitter, the photons will coalesce and leave together from the same output port. This is a quantum interference effect, which occurs because two possible paths-in which the photons leave by different output ports-interfere destructively. This effect was first observed in parametric downconversion (in which a nonlinear crystal splits a single photon into two photons of lower energy), then from two separate downconversion crystals, as well as with single photons produced one after the other by the same quantum emitter. With the recent developments in quantum information research, much attention has been devoted to this interference effect as a resource for quantum data processing using linear optics techniques. To ensure the scalability of schemes based on these ideas, it is crucial that indistinguishable photons are emitted by a collection of synchronized, but otherwise independent sources. Here we demonstrate the quantum interference of two single photons emitted by two independently trapped single atoms, bridging the gap towards the simultaneous emission of many indistinguishable single photons by different emitters. Our data analysis shows that the observed coalescence is mainly limited by wavefront matching of the light emitted by the two atoms, and to a lesser extent by the motion of each atom in its own trap.
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Affiliation(s)
- J Beugnon
- Laboratoire Charles Fabry de l'Institut d'Optique (UMR 8501), Bâtiment 503, Centre Universitaire, 91403 Orsay cedex, France
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48
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Childress L, Taylor JM, Sørensen AS, Lukin MD. Fault-tolerant quantum communication based on solid-state photon emitters. PHYSICAL REVIEW LETTERS 2006; 96:070504. [PMID: 16606069 DOI: 10.1103/physrevlett.96.070504] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Revised: 11/11/2005] [Indexed: 05/08/2023]
Abstract
We describe a novel protocol for a quantum repeater that enables long-distance quantum communication through realistic, lossy photonic channels. Contrary to previous proposals, our protocol incorporates active purification of arbitrary errors at each step of the protocol using only two qubits at each repeater station. Because of these minimal physical requirements, the present protocol can be realized in simple physical systems such as solid-state single photon emitters. As an example, we show how nitrogen-vacancy color centers in diamond can be used to implement the protocol, using the nuclear and electronic spin to form the two qubits.
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Affiliation(s)
- L Childress
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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49
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Volz J, Weber M, Schlenk D, Rosenfeld W, Vrana J, Saucke K, Kurtsiefer C, Weinfurter H. Observation of entanglement of a single photon with a trapped atom. PHYSICAL REVIEW LETTERS 2006; 96:030404. [PMID: 16486671 DOI: 10.1103/physrevlett.96.030404] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Indexed: 05/06/2023]
Abstract
We report the observation of entanglement between a single trapped atom and a single photon at a wavelength suitable for low-loss communication over large distances, thereby achieving a crucial step towards long range quantum networks. To verify the entanglement, we introduce a single atom state analysis. This technique is used for full state tomography of the atom-photon qubit pair. The detection efficiency and the entanglement fidelity are high enough to allow in a next step the generation of entangled atoms at large distances, ready for a final loophole-free Bell experiment.
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Affiliation(s)
- Jürgen Volz
- Department für Physik, Ludwig-Maximilians-Universität München, D-80799 München, Germany.
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50
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Darquié B, Jones MPA, Dingjan J, Beugnon J, Bergamini S, Sortais Y, Messin G, Browaeys A, Grangier P. Controlled Single-Photon Emission from a Single Trapped Two-Level Atom. Science 2005; 309:454-6. [PMID: 16020731 DOI: 10.1126/science.1113394] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
By illuminating an individual rubidium atom stored in a tight optical tweezer with short resonant light pulses, we created an efficient triggered source of single photons with a well-defined polarization. The measured intensity correlation of the emitted light pulses exhibits almost perfect antibunching. Such a source of high-rate, fully controlled single-photon pulses has many potential applications for quantum information processing.
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Affiliation(s)
- B Darquié
- Laboratoire Charles Fabry de l'Institut d'Optique (UMR 8501), Bâtiment 503, Centre Universitaire, 91403 Orsay, France
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