51
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Gu X, Krenn M, Erhard M, Zeilinger A. Gouy Phase Radial Mode Sorter for Light: Concepts and Experiments. PHYSICAL REVIEW LETTERS 2018; 120:103601. [PMID: 29570339 DOI: 10.1103/physrevlett.120.103601] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Indexed: 05/27/2023]
Abstract
We present an in principle lossless sorter for radial modes of light, using accumulated Gouy phases. The experimental setups have been found by a computer algorithm, and can be intuitively understood in a geometric way. Together with the ability to sort angular-momentum modes, we now have access to the complete two-dimensional transverse plane of light. The device can readily be used in multiplexing classical information. On a quantum level, it is an analog of the Stern-Gerlach experiment-significant for the discussion of fundamental concepts in quantum physics. As such, it can be applied in high-dimensional and multiphotonic quantum experiments.
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Affiliation(s)
- Xuemei Gu
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- State Key Laboratory for Novel Software Technology, Nanjing University, 163 Xianlin Avenue, Qixia District, 210023 Nanjing City, China
| | - Mario Krenn
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Manuel Erhard
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Anton Zeilinger
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
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52
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Kraft T, Ritz C, Brunner N, Huber M, Gühne O. Characterizing Genuine Multilevel Entanglement. PHYSICAL REVIEW LETTERS 2018; 120:060502. [PMID: 29481227 DOI: 10.1103/physrevlett.120.060502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Indexed: 05/02/2023]
Abstract
Entanglement of high-dimensional quantum systems has become increasingly important for quantum communication and experimental tests of nonlocality. However, many effects of high-dimensional entanglement can be simulated by using multiple copies of low-dimensional systems. We present a general theory to characterize those high-dimensional quantum states for which the correlations cannot simply be simulated by low-dimensional systems. Our approach leads to general criteria for detecting multilevel entanglement in multiparticle quantum states, which can be used to verify these phenomena experimentally.
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Affiliation(s)
- Tristan Kraft
- Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Straße 3, 57068 Siegen, Germany
| | - Christina Ritz
- Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Straße 3, 57068 Siegen, Germany
| | - Nicolas Brunner
- Département de Physique Appliquée, Université de Genève, 1211 Genève, Switzerland
| | - Marcus Huber
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-1090 Vienna, Austria
| | - Otfried Gühne
- Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Straße 3, 57068 Siegen, Germany
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53
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Melnikov AA, Poulsen Nautrup H, Krenn M, Dunjko V, Tiersch M, Zeilinger A, Briegel HJ. Active learning machine learns to create new quantum experiments. Proc Natl Acad Sci U S A 2018; 115:1221-1226. [PMID: 29348200 PMCID: PMC5819408 DOI: 10.1073/pnas.1714936115] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
How useful can machine learning be in a quantum laboratory? Here we raise the question of the potential of intelligent machines in the context of scientific research. A major motivation for the present work is the unknown reachability of various entanglement classes in quantum experiments. We investigate this question by using the projective simulation model, a physics-oriented approach to artificial intelligence. In our approach, the projective simulation system is challenged to design complex photonic quantum experiments that produce high-dimensional entangled multiphoton states, which are of high interest in modern quantum experiments. The artificial intelligence system learns to create a variety of entangled states and improves the efficiency of their realization. In the process, the system autonomously (re)discovers experimental techniques which are only now becoming standard in modern quantum optical experiments-a trait which was not explicitly demanded from the system but emerged through the process of learning. Such features highlight the possibility that machines could have a significantly more creative role in future research.
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Affiliation(s)
- Alexey A Melnikov
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria;
| | | | - Mario Krenn
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Vedran Dunjko
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
| | - Markus Tiersch
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
| | - Anton Zeilinger
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, 1090 Vienna, Austria;
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Hans J Briegel
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
- Department of Philosophy, University of Konstanz, 78457 Konstanz, Germany
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54
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Tasca DS, Sánchez P, Walborn SP, Rudnicki Ł. Mutual Unbiasedness in Coarse-Grained Continuous Variables. PHYSICAL REVIEW LETTERS 2018; 120:040403. [PMID: 29437426 DOI: 10.1103/physrevlett.120.040403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/09/2017] [Indexed: 06/08/2023]
Abstract
The notion of mutual unbiasedness for coarse-grained measurements of quantum continuous variable systems is considered. It is shown that while the procedure of "standard" coarse graining breaks the mutual unbiasedness between conjugate variables, this desired feature can be theoretically established and experimentally observed in periodic coarse graining. We illustrate our results in an optics experiment implementing Fraunhofer diffraction through a periodic diffraction grating, finding excellent agreement with the derived theory. Our results are an important step in developing a formal connection between discrete and continuous variable quantum mechanics.
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Affiliation(s)
- Daniel S Tasca
- Instituto de Física, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24210-346, Brazil
| | - Piero Sánchez
- Departamento de Ciencias, Sección Física, Pontificia Universidad Católica del Perú, Apartado 1761, Lima, Peru
| | - Stephen P Walborn
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, Rio de Janeiro 21941-972, Brazil
| | - Łukasz Rudnicki
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
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55
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Zeng Q, Wang B, Li P, Zhang X. Experimental High-Dimensional Einstein-Podolsky-Rosen Steering. PHYSICAL REVIEW LETTERS 2018; 120:030401. [PMID: 29400498 DOI: 10.1103/physrevlett.120.030401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Indexed: 06/07/2023]
Abstract
Steering nonlocality is the fundamental property of quantum mechanics, which has been widely demonstrated in some systems with qubits. Recently, theoretical works have shown that the high-dimensional (HD) steering effect exhibits novel and important features, such as noise suppression, which appear promising for potential application in quantum information processing (QIP). However, experimental observation of these HD properties remains a great challenge to date. In this work, we demonstrate the HD steering effect by encoding with orbital angular momentum photons for the first time. More importantly, we have quantitatively certified the noise-suppression phenomenon in the HD steering effect by introducing a tunable isotropic noise. We believe our results represent a significant advance of the nonlocal steering study and have direct benefits for QIP applications with superior capacity and reliability.
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Affiliation(s)
- Qiang Zeng
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, 100081 Beijing, China
| | - Bo Wang
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, 100081 Beijing, China
| | - Pengyun Li
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, 100081 Beijing, China
| | - Xiangdong Zhang
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, 100081 Beijing, China
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56
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Abstract
High-dimensional quantum entanglement can enrich the functionality of quantum information processing. For example, it can enhance the channel capacity for linear optic superdense coding and decrease the error rate threshold of quantum key distribution. Long-distance distribution of a high-dimensional entanglement is essential for such advanced quantum communications over a communications network. Here, we show a long-distance distribution of a four-dimensional entanglement. We employ time-bin entanglement, which is suitable for a fibre transmission, and implement scalable measurements for the high-dimensional entanglement using cascaded Mach-Zehnder interferometers. We observe that a pair of time-bin entangled photons has more than 1 bit of secure information capacity over 100 km. Our work constitutes an important step towards secure and dense quantum communications in a large Hilbert space.
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57
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Zhou Y, Mirhosseini M, Fu D, Zhao J, Hashemi Rafsanjani SM, Willner AE, Boyd RW. Sorting Photons by Radial Quantum Number. PHYSICAL REVIEW LETTERS 2017; 119:263602. [PMID: 29328697 DOI: 10.1103/physrevlett.119.263602] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Indexed: 06/07/2023]
Abstract
The Laguerre-Gaussian (LG) modes constitute a complete basis set for representing the transverse structure of a paraxial photon field in free space. Earlier workers have shown how to construct a device for sorting a photon according to its azimuthal LG mode index, which describes the orbital angular momentum (OAM) carried by the field. In this paper we propose and demonstrate a mode sorter based on the fractional Fourier transform to efficiently decompose the optical field according to its radial profile. We experimentally characterize the performance of our implementation by separating individual radial modes as well as superposition states. The reported scheme can, in principle, achieve unit efficiency and thus can be suitable for applications that involve quantum states of light. This approach can be readily combined with existing OAM mode sorters to provide a complete characterization of the transverse profile of the optical field.
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Affiliation(s)
- Yiyu Zhou
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - Mohammad Mirhosseini
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - Dongzhi Fu
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
- Key Laboratory for Quantum Information and Quantum Optoelectronic Devices, Department of Applied Physics, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China
| | - Jiapeng Zhao
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | | | - Alan E Willner
- Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA
| | - Robert W Boyd
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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58
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Wavevector multiplexed atomic quantum memory via spatially-resolved single-photon detection. Nat Commun 2017; 8:2140. [PMID: 29247218 PMCID: PMC5732182 DOI: 10.1038/s41467-017-02366-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 11/21/2017] [Indexed: 11/18/2022] Open
Abstract
Parallelized quantum information processing requires tailored quantum memories to simultaneously handle multiple photons. The spatial degree of freedom is a promising candidate to facilitate such photonic multiplexing. Using a single-photon resolving camera, we demonstrate a wavevector multiplexed quantum memory based on a cold atomic ensemble. Observation of nonclassical correlations between Raman scattered photons is confirmed by an average value of the second-order correlation function \documentclass[12pt]{minimal}
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\begin{document}$$g_{{\mathrm{S,AS}}}^{{\mathrm{(2)}}} = 72 \pm 5$$\end{document}gS,AS(2)=72±5 in 665 separated modes simultaneously. The proposed protocol utilizing the multimode memory along with the camera will facilitate generation of multi-photon states, which are a necessity in quantum-enhanced sensing technologies and as an input to photonic quantum circuits. Multiplexing of quantum memories could boost the efficiency of photon state preparation. Here, the authors use a cold atomic ensemble and a single-photon resolving camera to exploit emission multiplexing of Raman photons from 665 different angular modes, confirming nonclassical photon-number correlations.
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59
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Babazadeh A, Erhard M, Wang F, Malik M, Nouroozi R, Krenn M, Zeilinger A. High-Dimensional Single-Photon Quantum Gates: Concepts and Experiments. PHYSICAL REVIEW LETTERS 2017; 119:180510. [PMID: 29219590 DOI: 10.1103/physrevlett.119.180510] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Indexed: 06/07/2023]
Abstract
Transformations on quantum states form a basic building block of every quantum information system. From photonic polarization to two-level atoms, complete sets of quantum gates for a variety of qubit systems are well known. For multilevel quantum systems beyond qubits, the situation is more challenging. The orbital angular momentum modes of photons comprise one such high-dimensional system for which generation and measurement techniques are well studied. However, arbitrary transformations for such quantum states are not known. Here we experimentally demonstrate a four-dimensional generalization of the Pauli X gate and all of its integer powers on single photons carrying orbital angular momentum. Together with the well-known Z gate, this forms the first complete set of high-dimensional quantum gates implemented experimentally. The concept of the X gate is based on independent access to quantum states with different parities and can thus be generalized to other photonic degrees of freedom and potentially also to other quantum systems.
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Affiliation(s)
- Amin Babazadeh
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Physics Department, Institute for Advanced Studies in Basic Sciences (IASBS), Gavazang Road, Zanjan 45137-66731, Iran
| | - Manuel Erhard
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Feiran Wang
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, Shaanxi Province, Xi'an Jiaotong University, Xi'an 710049, China
| | - Mehul Malik
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Rahman Nouroozi
- Physics Department, Institute for Advanced Studies in Basic Sciences (IASBS), Gavazang Road, Zanjan 45137-66731, Iran
| | - Mario Krenn
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Anton Zeilinger
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
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60
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Zhang Y, Agnew M, Roger T, Roux FS, Konrad T, Faccio D, Leach J, Forbes A. Simultaneous entanglement swapping of multiple orbital angular momentum states of light. Nat Commun 2017; 8:632. [PMID: 28935969 PMCID: PMC5608840 DOI: 10.1038/s41467-017-00706-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 07/21/2017] [Indexed: 12/03/2022] Open
Abstract
High-bit-rate long-distance quantum communication is a proposed technology for future communication networks and relies on high-dimensional quantum entanglement as a core resource. While it is known that spatial modes of light provide an avenue for high-dimensional entanglement, the ability to transport such quantum states robustly over long distances remains challenging. To overcome this, entanglement swapping may be used to generate remote quantum correlations between particles that have not interacted; this is the core ingredient of a quantum repeater, akin to repeaters in optical fibre networks. Here we demonstrate entanglement swapping of multiple orbital angular momentum states of light. Our approach does not distinguish between different anti-symmetric states, and thus entanglement swapping occurs for several thousand pairs of spatial light modes simultaneously. This work represents the first step towards a quantum network for high-dimensional entangled states and provides a test bed for fundamental tests of quantum science. Entanglement swapping in high dimensions requires large numbers of entangled photons and consequently suffers from low photon flux. Here the authors demonstrate entanglement swapping of multiple spatial modes of light simultaneously, without the need for increasing the photon numbers with dimension.
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Affiliation(s)
- Yingwen Zhang
- CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa.,Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario, K1N 6N5, Canada
| | - Megan Agnew
- IPaQS, SUPA, Heriot-Watt, Edinburgh, EH14 4AS, UK
| | - Thomas Roger
- IPaQS, SUPA, Heriot-Watt, Edinburgh, EH14 4AS, UK
| | - Filippus S Roux
- CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa.,School of Physics, University of Witwatersrand, Johannesburg, 2000, South Africa.,National Metrology Institute of South Africa, Meiring Naude Road, Pretoria, South Africa
| | - Thomas Konrad
- School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.,National Institute of Theoretical Physics, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa
| | | | | | - Andrew Forbes
- CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa.,School of Physics, University of Witwatersrand, Johannesburg, 2000, South Africa
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61
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Lee HJ, Choi SK, Park HS. Experimental Demonstration of Four-Dimensional Photonic Spatial Entanglement between Multi-core Optical Fibres. Sci Rep 2017; 7:4302. [PMID: 28655886 PMCID: PMC5487350 DOI: 10.1038/s41598-017-04444-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 05/16/2017] [Indexed: 11/26/2022] Open
Abstract
Fibre transport of multi-dimensional photonic quantum states promises high information capacity per photon without space restriction. This work experimentally demonstrates transmission of spatial ququarts through multi-core optical fibres and measurement of the entanglement between two fibres with quantum state analyzers, each composed of a spatial light modulator and a single-mode fibre. Quantum state tomography reconstructs the four-dimension entangled state that verifies the nonlocality through concurrences in two-dimensional subspaces, a lower bound of four-dimensional concurrence and a Bell-type CGLMP inequality.
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Affiliation(s)
- Hee Jung Lee
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea
| | - Sang-Kyung Choi
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea
| | - Hee Su Park
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea.
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62
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Cheng ZD, Liu ZD, Luo XW, Zhou ZW, Wang J, Li Q, Wang YT, Tang JS, Xu JS, Li CF, Guo GC. Degenerate cavity supporting more than 31 Laguerre-Gaussian modes. OPTICS LETTERS 2017; 42:2042-2045. [PMID: 28504744 DOI: 10.1364/ol.42.002042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Photons propagating in Laguerre-Gaussian modes have characteristic orbital angular momenta, which are fundamental optical degrees of freedom. The orbital angular momentum of light has potential application in high-capacity optical communication and even in quantum information processing. In this work, we experimentally construct a ring cavity with four lenses and four mirrors that is completely degenerate for Laguerre-Gaussian modes. By measuring the transmitted peaks and patterns of different modes, the ring cavity is shown to support more than 31 Laguerre-Gaussian modes. The constructed degenerate cavity opens a new way for using the unlimited resource of available angular momentum states simultaneously.
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63
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Abstract
We propose space-variant uniaxial flat optical elements designed to generate pure Laguerre-Gaussian modes with arbitrary azimuthal and radial indices l and p from an incident Gaussian beam. This is done via the combined use of the dynamic and the geometric phases. Optimal design protocol for the mode conversion efficiency is derived, and the corresponding characteristics are given for -6≤l≤6 and 0≤p≤5. The obtained "modal q-plates" may find many applications whenever the radial degree of freedom of a light field is at play.
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64
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Ji YQ, Shao XQ, Yi XX. Fusing atomic W states via quantum Zeno dynamics. Sci Rep 2017; 7:1378. [PMID: 28469164 PMCID: PMC5431237 DOI: 10.1038/s41598-017-01499-5] [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: 01/18/2017] [Accepted: 03/29/2017] [Indexed: 11/09/2022] Open
Abstract
We propose a scheme for preparation of large-scale entangled W states based on the fusion mechanism via quantum Zeno dynamics. By sending two atoms belonging to an n-atom W state and an m-atom W state, respectively, into a vacuum cavity (or two separate cavities), we may obtain a (n + m - 2)-atom W state via detecting the two-atom state after interaction. The present scheme is robust against both spontaneous emission of atoms and decay of cavity, and the feasibility analysis indicates that it can also be realized in experiment.
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Affiliation(s)
- Y Q Ji
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun, 130024, China
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun, 130024, China
| | - X Q Shao
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun, 130024, China.
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun, 130024, China.
| | - X X Yi
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun, 130024, China.
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun, 130024, China.
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65
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Martin L, Mardani D, Kondakci HE, Larson WD, Shabahang S, Jahromi AK, Malhotra T, Vamivakas AN, Atia GK, Abouraddy AF. Basis-neutral Hilbert-space analyzers. Sci Rep 2017; 7:44995. [PMID: 28344331 PMCID: PMC5366812 DOI: 10.1038/srep44995] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 02/20/2017] [Indexed: 12/03/2022] Open
Abstract
Interferometry is one of the central organizing principles of optics. Key to interferometry is the concept of optical delay, which facilitates spectral analysis in terms of time-harmonics. In contrast, when analyzing a beam in a Hilbert space spanned by spatial modes – a critical task for spatial-mode multiplexing and quantum communication – basis-specific principles are invoked that are altogether distinct from that of ‘delay’. Here, we extend the traditional concept of temporal delay to the spatial domain, thereby enabling the analysis of a beam in an arbitrary spatial-mode basis – exemplified using Hermite-Gaussian and radial Laguerre-Gaussian modes. Such generalized delays correspond to optical implementations of fractional transforms; for example, the fractional Hankel transform is the generalized delay associated with the space of Laguerre-Gaussian modes, and an interferometer incorporating such a ‘delay’ obtains modal weights in the associated Hilbert space. By implementing an inherently stable, reconfigurable spatial-light-modulator-based polarization-interferometer, we have constructed a ‘Hilbert-space analyzer’ capable of projecting optical beams onto any modal basis.
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Affiliation(s)
- Lane Martin
- CREOL, The College of Optics &Photonics, University of Central Florida, Orlando, FL 32816, USA
| | - Davood Mardani
- Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - H Esat Kondakci
- CREOL, The College of Optics &Photonics, University of Central Florida, Orlando, FL 32816, USA
| | - Walker D Larson
- CREOL, The College of Optics &Photonics, University of Central Florida, Orlando, FL 32816, USA
| | - Soroush Shabahang
- CREOL, The College of Optics &Photonics, University of Central Florida, Orlando, FL 32816, USA
| | - Ali K Jahromi
- CREOL, The College of Optics &Photonics, University of Central Florida, Orlando, FL 32816, USA
| | - Tanya Malhotra
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.,Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - A Nick Vamivakas
- Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA.,Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - George K Atia
- Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - Ayman F Abouraddy
- CREOL, The College of Optics &Photonics, University of Central Florida, Orlando, FL 32816, USA
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66
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Martin A, Guerreiro T, Tiranov A, Designolle S, Fröwis F, Brunner N, Huber M, Gisin N. Quantifying Photonic High-Dimensional Entanglement. PHYSICAL REVIEW LETTERS 2017; 118:110501. [PMID: 28368623 DOI: 10.1103/physrevlett.118.110501] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Indexed: 06/07/2023]
Abstract
High-dimensional entanglement offers promising perspectives in quantum information science. In practice, however, the main challenge is to devise efficient methods to characterize high-dimensional entanglement, based on the available experimental data which is usually rather limited. Here we report the characterization and certification of high-dimensional entanglement in photon pairs, encoded in temporal modes. Building upon recently developed theoretical methods, we certify an entanglement of formation of 2.09(7) ebits in a time-bin implementation, and 4.1(1) ebits in an energy-time implementation. These results are based on very limited sets of local measurements, which illustrates the practical relevance of these methods.
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Affiliation(s)
- Anthony Martin
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Thiago Guerreiro
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Alexey Tiranov
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | | | - Florian Fröwis
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Nicolas Brunner
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Marcus Huber
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-1090 Vienna, Austria
| | - Nicolas Gisin
- Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
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Krenn M, Malik M, Erhard M, Zeilinger A. Orbital angular momentum of photons and the entanglement of Laguerre-Gaussian modes. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:20150442. [PMID: 28069773 PMCID: PMC5247486 DOI: 10.1098/rsta.2015.0442] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/09/2016] [Indexed: 05/17/2023]
Abstract
The identification of orbital angular momentum (OAM) as a fundamental property of a beam of light nearly 25 years ago has led to an extensive body of research around this topic. The possibility that single photons can carry OAM has made this degree of freedom an ideal candidate for the investigation of complex quantum phenomena and their applications. Research in this direction has ranged from experiments on complex forms of quantum entanglement to the interaction between light and quantum states of matter. Furthermore, the use of OAM in quantum information has generated a lot of excitement, as it allows for encoding large amounts of information on a single photon. Here, we explain the intuition that led to the first quantum experiment with OAM 15 years ago. We continue by reviewing some key experiments investigating fundamental questions on photonic OAM and the first steps to applying these properties in novel quantum protocols. At the end, we identify several interesting open questions that could form the subject of future investigations with OAM.This article is part of the themed issue 'Optical orbital angular momentum'.
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Affiliation(s)
- Mario Krenn
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Mehul Malik
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Manuel Erhard
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Anton Zeilinger
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
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68
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Allen GW, Meyer DA. Polynomial Monogamy Relations for Entanglement Negativity. PHYSICAL REVIEW LETTERS 2017; 118:080402. [PMID: 28282169 DOI: 10.1103/physrevlett.118.080402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Indexed: 06/06/2023]
Abstract
The notion of nonclassical correlations is a powerful contrivance for explaining phenomena exhibited in quantum systems. It is well known, however, that quantum systems are not free to explore arbitrary correlations-the church of the smaller Hilbert space only accepts monogamous congregants. We demonstrate how to characterize the limits of what is quantum mechanically possible with a computable measure, entanglement negativity. We show that negativity only saturates the standard linear monogamy inequality in trivial cases implied by its monotonicity under local operations and classical communication, and derive a necessary and sufficient inequality which, for the first time, is a nonlinear higher degree polynomial. For very large quantum systems, we prove that the negativity can be distributed at least linearly for the tightest constraint and conjecture that it is at most linear.
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Affiliation(s)
- Grant W Allen
- Department of Physics, University of California at San Diego, La Jolla, California 92093-0354, USA
| | - David A Meyer
- Department of Mathematics, University of California at San Diego, La Jolla, California 92093-0112, USA
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69
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Krenn M, Hochrainer A, Lahiri M, Zeilinger A. Entanglement by Path Identity. PHYSICAL REVIEW LETTERS 2017; 118:080401. [PMID: 28282180 DOI: 10.1103/physrevlett.118.080401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Indexed: 05/11/2023]
Abstract
Quantum entanglement is one of the most prominent features of quantum mechanics and forms the basis of quantum information technologies. Here we present a novel method for the creation of quantum entanglement in multipartite and high-dimensional systems. The two ingredients are (i) superposition of photon pairs with different origins and (ii) aligning photons such that their paths are identical. We explain the experimentally feasible creation of various classes of multiphoton entanglement encoded in polarization as well as in high-dimensional Hilbert spaces-starting only from nonentangled photon pairs. For two photons, arbitrary high-dimensional entanglement can be created. The idea of generating entanglement by path identity could also apply to quantum entities other than photons. We discovered the technique by analyzing the output of a computer algorithm. This shows that computer designed quantum experiments can be inspirations for new techniques.
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Affiliation(s)
- Mario Krenn
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria and Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Armin Hochrainer
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria and Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Mayukh Lahiri
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria and Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
| | - Anton Zeilinger
- Vienna Center for Quantum Science & Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria and Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
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70
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Bouchard F, Fickler R, Boyd RW, Karimi E. High-dimensional quantum cloning and applications to quantum hacking. SCIENCE ADVANCES 2017; 3:e1601915. [PMID: 28168219 PMCID: PMC5291699 DOI: 10.1126/sciadv.1601915] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 12/14/2016] [Indexed: 05/20/2023]
Abstract
Attempts at cloning a quantum system result in the introduction of imperfections in the state of the copies. This is a consequence of the no-cloning theorem, which is a fundamental law of quantum physics and the backbone of security for quantum communications. Although perfect copies are prohibited, a quantum state may be copied with maximal accuracy via various optimal cloning schemes. Optimal quantum cloning, which lies at the border of the physical limit imposed by the no-signaling theorem and the Heisenberg uncertainty principle, has been experimentally realized for low-dimensional photonic states. However, an increase in the dimensionality of quantum systems is greatly beneficial to quantum computation and communication protocols. Nonetheless, no experimental demonstration of optimal cloning machines has hitherto been shown for high-dimensional quantum systems. We perform optimal cloning of high-dimensional photonic states by means of the symmetrization method. We show the universality of our technique by conducting cloning of numerous arbitrary input states and fully characterize our cloning machine by performing quantum state tomography on cloned photons. In addition, a cloning attack on a Bennett and Brassard (BB84) quantum key distribution protocol is experimentally demonstrated to reveal the robustness of high-dimensional states in quantum cryptography.
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Affiliation(s)
- Frédéric Bouchard
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Robert Fickler
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Robert W. Boyd
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
- Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Ebrahim Karimi
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
- Department of Physics, Institute for Advanced Studies in Basic Sciences, 45137-66731 Zanjan, Iran
- Corresponding author.
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71
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Deng FG, Ren BC, Li XH. Quantum hyperentanglement and its applications in quantum information processing. Sci Bull (Beijing) 2017; 62:46-68. [PMID: 36718070 DOI: 10.1016/j.scib.2016.11.007] [Citation(s) in RCA: 163] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 11/14/2016] [Accepted: 11/14/2016] [Indexed: 02/01/2023]
Abstract
Hyperentanglement is a promising resource in quantum information processing with its high capacity character, defined as the entanglement in multiple degrees of freedom (DOFs) of a quantum system, such as polarization, spatial-mode, orbit-angular-momentum, time-bin and frequency DOFs of photons. Recently, hyperentanglement attracts much attention as all the multiple DOFs can be used to carry information in quantum information processing fully. In this review, we present an overview of the progress achieved so far in the field of hyperentanglement in photon systems and some of its important applications in quantum information processing, including hyperentanglement generation, complete hyperentangled-Bell-state analysis, hyperentanglement concentration, and hyperentanglement purification for high-capacity long-distance quantum communication. Also, a scheme for hyper-controlled-not gate is introduced for hyperparallel photonic quantum computation, which can perform two controlled-not gate operations on both the polarization and spatial-mode DOFs and depress the resources consumed and the photonic dissipation.
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Affiliation(s)
- Fu-Guo Deng
- Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China.
| | - Bao-Cang Ren
- Department of Physics, Capital Normal University, Beijing 100048, China.
| | - Xi-Han Li
- Department of Physics, Chongqing University, Chongqing 400044, China; Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
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72
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Avetisyan H, Monken CH. Mode analysis of higher-order transverse-mode correlation beams in a turbulent atmosphere. OPTICS LETTERS 2017; 42:101-104. [PMID: 28059185 DOI: 10.1364/ol.42.000101] [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
Due to the transfer of the angular spectrum of the pump beam to the two-photon state in spontaneous parametric downconversion, the generated twin photons are entangled in their spatial degrees of freedom. This spatial entanglement can be observed through correlation measurements in any set of modes in which one may choose to perform measurements. Choosing, e.g., a Hermite-Gaussian (HG) set of spatial modes as a basis, one can observe correlations present in their spatial degrees of freedom. In addition, these modes can be used as alphabets for quantum communication. For global quantum communication purposes, we derive an analytic expression for two-photon detection probability in terms of HG modes, taking into account the effects of the turbulent atmosphere. Our result is more general as it accounts for the propagation of both signal and idler photons through the atmosphere, as opposed to other works considering one photon's propagation in vacuum. We show that while the restrictions on both the parity and order of the downconverted HG fields no longer hold, due to the crosstalk between modes when propagating in the atmosphere, the crosstalk is not uniform: there are more robust modes that tend to keep the photons in them. These modes can be employed in order to increase the fidelity of quantum communication.
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73
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De Assis PL, Carvalho MAD, Berruezo LP, Ferraz J, Pádua S. Generation of two pairs of qudits using four photons and a single degree of freedom. OPTICS EXPRESS 2016; 24:30149-30163. [PMID: 28059292 DOI: 10.1364/oe.24.030149] [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
Qudits, d-level quantum systems, have been shown to provide a better resource for quantum key distribution and other Quantum Information protocols. It is customary to generate photonic qudits using more than one degree of freedom of the same photon. In much the same way, multi-qubit states are generated using only a pair of photons and ingenious ways to manipulate more than one degree of freedom independently. In contrast to such costly implementations in terms of quantum resources, we present the controlled generation of two copies of two-qudit states using four photons and a single degree of freedom, transverse momentum. The degree of entanglement within each pair was inferred by exploiting the availability of two copies of the same state, without the need of a full tomographic reconstruction of the states, and both highly-entangled and separable states were generated. We show theoretically that the set of states obtainable using our setup is very diverse, ranging from maximally entangled states of qudits to separable states.
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74
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Unternährer M, Bessire B, Gasparini L, Stoppa D, Stefanov A. Coincidence detection of spatially correlated photon pairs with a monolithic time-resolving detector array. OPTICS EXPRESS 2016; 24:28829-28841. [PMID: 27958526 DOI: 10.1364/oe.24.028829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We demonstrate coincidence measurements of spatially entangled photons by means of a multi-pixel based detection array. The sensor, originally developed for positron emission tomography applications, is a fully digital 8×16 silicon photomultiplier array allowing not only photon counting but also per-pixel time stamping of the arrived photons with an effective resolution of 265 ps. Together with a frame rate of 500 kfps, this property exceeds the capabilities of conventional charge-coupled device cameras which have become of growing interest for the detection of transversely correlated photon pairs. The sensor is used to measure a second-order correlation function for various non-collinear configurations of entangled photons generated by spontaneous parametric down-conversion. The experimental results are compared to theory.
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75
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Tiranov A, Strassmann PC, Lavoie J, Brunner N, Huber M, Verma VB, Nam SW, Mirin RP, Lita AE, Marsili F, Afzelius M, Bussières F, Gisin N. Temporal Multimode Storage of Entangled Photon Pairs. PHYSICAL REVIEW LETTERS 2016; 117:240506. [PMID: 28009181 DOI: 10.1103/physrevlett.117.240506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Indexed: 06/06/2023]
Abstract
Multiplexed quantum memories capable of storing and processing entangled photons are essential for the development of quantum networks. In this context, we demonstrate and certify the simultaneous storage and retrieval of two entangled photons inside a solid-state quantum memory and measure a temporal multimode capacity of ten modes. This is achieved by producing two polarization-entangled pairs from parametric down-conversion and mapping one photon of each pair onto a rare-earth-ion-doped (REID) crystal using the atomic frequency comb (AFC) protocol. We develop a concept of indirect entanglement witnesses, which can be used as Schmidt number witnesses, and we use it to experimentally certify the presence of more than one entangled pair retrieved from the quantum memory. Our work puts forward REID-AFC as a platform compatible with temporal multiplexing of several entangled photon pairs along with a new entanglement certification method, useful for the characterization of multiplexed quantum memories.
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Affiliation(s)
- Alexey Tiranov
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
| | - Peter C Strassmann
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
| | - Jonathan Lavoie
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
| | - Nicolas Brunner
- Département Physique Théorique, Université de Genève, CH-1211 Genève, Switzerland
| | - Marcus Huber
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Varun B Verma
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Sae Woo Nam
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Richard P Mirin
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Adriana E Lita
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Francesco Marsili
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91109, USA
| | - Mikael Afzelius
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
| | - Félix Bussières
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
| | - Nicolas Gisin
- Groupe de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
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76
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Abstract
Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.
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77
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Quantum entanglement of angular momentum states with quantum numbers up to 10,010. Proc Natl Acad Sci U S A 2016; 113:13642-13647. [PMID: 27856742 DOI: 10.1073/pnas.1616889113] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon.
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78
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Experimental realization of entanglement in multiple degrees of freedom between two quantum memories. Nat Commun 2016; 7:13514. [PMID: 27841274 PMCID: PMC5114578 DOI: 10.1038/ncomms13514] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 10/07/2016] [Indexed: 11/18/2022] Open
Abstract
Entanglement in multiple degrees of freedom has many benefits over entanglement in a single one. The former enables quantum communication with higher channel capacity and more efficient quantum information processing and is compatible with diverse quantum networks. Establishing multi-degree-of-freedom entangled memories is not only vital for high-capacity quantum communication and computing, but also promising for enhanced violations of nonlocality in quantum systems. However, there have been yet no reports of the experimental realization of multi-degree-of-freedom entangled memories. Here we experimentally established hyper- and hybrid entanglement in multiple degrees of freedom, including path (K-vector) and orbital angular momentum, between two separated atomic ensembles by using quantum storage. The results are promising for achieving quantum communication and computing with many degrees of freedom. Establishing multi-degree-of-freedom entangled memories is important for high-capacity quantum communications and computing. Here, authors experimentally demonstrate hyper- and hybrid entanglement between two atomic ensembles in multiple degrees of freedom including path and orbital angular momentum.
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79
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Ding DS, Zhang W, Shi S, Zhou ZY, Li Y, Shi BS, Guo GC. High-dimensional entanglement between distant atomic-ensemble memories. LIGHT, SCIENCE & APPLICATIONS 2016; 5:e16157. [PMID: 30167124 PMCID: PMC6059826 DOI: 10.1038/lsa.2016.157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 04/19/2016] [Accepted: 04/19/2016] [Indexed: 05/14/2023]
Abstract
Entangled quantum states in high-dimensional space show many advantages compared with entangled states in two-dimensional space. The former enable quantum communication with higher channel capacity, enable more efficient quantum-information processing and are more feasible for closing the detection loophole in Bell test experiments. Establishing high-dimensional entangled memories is essential for long-distance communication, but its experimental realization is lacking. We experimentally established high-dimensional entanglement in orbital angular momentum space between two atomic ensembles separated by 1 m. We reconstructed the density matrix for a three-dimensional entanglement and obtained an entanglement fidelity of (83.9±2.9)%. More importantly, we confirmed the successful preparation of a state entangled in more than three-dimensional space (up to seven-dimensional) using entanglement witnesses. Achieving high-dimensional entanglement represents a significant step toward a high-capacity quantum network.
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Affiliation(s)
- Dong-Sheng Ding
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Zhang
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shuai Shi
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhi-Yuan Zhou
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yan Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bao-Sen Shi
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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80
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Zhou ZY, Liu SL, Li Y, Ding DS, Zhang W, Shi S, Dong MX, Shi BS, Guo GC. Orbital Angular Momentum-Entanglement Frequency Transducer. PHYSICAL REVIEW LETTERS 2016; 117:103601. [PMID: 27636474 DOI: 10.1103/physrevlett.117.103601] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Indexed: 06/06/2023]
Abstract
Entanglement is a vital resource for realizing many tasks such as teleportation, secure key distribution, metrology, and quantum computations. To effectively build entanglement between different quantum systems and share information between them, a frequency transducer to convert between quantum states of different wavelengths while retaining its quantum features is indispensable. Information encoded in the photon's orbital angular momentum (OAM) degrees of freedom is preferred in harnessing the information-carrying capacity of a single photon because of its unlimited dimensions. A quantum transducer, which operates at wavelengths from 1558.3 to 525 nm for OAM qubits, OAM-polarization hybrid-entangled states, and OAM-entangled states, is reported for the first time. Nonclassical properties and entanglements are demonstrated following the conversion process by performing quantum tomography, interference, and Bell inequality measurements. Our results demonstrate the capability to create an entanglement link between different quantum systems operating in a photon's OAM degrees of freedom, which will be of great importance in building a high-capacity OAM quantum network.
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Affiliation(s)
- Zhi-Yuan Zhou
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shi-Long Liu
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yan Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Dong-Sheng Ding
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Zhang
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shuai Shi
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ming-Xin Dong
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bao-Sen Shi
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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81
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Pedrotti LM, Agha I. Theoertical investigation of quantum waveform shaping for single photon emitters. OPTICS EXPRESS 2016; 24:16687-16694. [PMID: 27464122 DOI: 10.1364/oe.24.016687] [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 investigate a new technique for quantum-compatible waveform shaping that extends the time lens method, and relies only on phase operations. Under realistic experimental conditions, we show that it is possible to both temporally compress and shape optical waveforms in the nanosecond to tens of picoseconds range, which is generally difficult to achieve using standard dispersive pulse-shaping techniques.
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82
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He LY, Wang TJ, Wang C. Construction of high-dimensional universal quantum logic gates using a Λ system coupled with a whispering-gallery-mode microresonator. OPTICS EXPRESS 2016; 24:15429-15445. [PMID: 27410818 DOI: 10.1364/oe.24.015429] [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-dimensional quantum system provides a higher capacity of quantum channel, which exhibits potential applications in quantum information processing. However, high-dimensional universal quantum logic gates is difficult to achieve directly with only high-dimensional interaction between two quantum systems and requires a large number of two-dimensional gates to build even a small high-dimensional quantum circuits. In this paper, we propose a scheme to implement a general controlled-flip (CF) gate where the high-dimensional single photon serve as the target qudit and stationary qubits work as the control logic qudit, by employing a three-level Λ-type system coupled with a whispering-gallery-mode microresonator. In our scheme, the required number of interaction times between the photon and solid state system reduce greatly compared with the traditional method which decomposes the high-dimensional Hilbert space into 2-dimensional quantum space, and it is on a shorter temporal scale for the experimental realization. Moreover, we discuss the performance and feasibility of our hybrid CF gate, concluding that it can be easily extended to a 2n-dimensional case and it is feasible with current technology.
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83
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Abstract
Measuring the state of a quantum system is a fundamental process in quantum mechanics and plays an essential role in quantum information and quantum technologies. One method to measure a quantum observable is to sort the system in different spatial modes according to the measured value, followed by single-particle detectors on each mode. Examples of quantum sorters are polarizing beam-splitters (PBS) – which direct photons according to their polarization – and Stern-Gerlach devices. Here we propose a general scheme to sort a quantum system according to the value of any d-dimensional degree of freedom, such as spin, orbital angular momentum (OAM), wavelength etc. Our scheme is universal, works at the single-particle level and has a theoretical efficiency of 100%. As an application we design an efficient OAM sorter consisting of a single multi-path interferometer which is suitable for a photonic chip implementation.
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Affiliation(s)
- Radu Ionicioiu
- Department of Theoretical Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, 077125 Bucharest-Măgurele, Romania.,Research Center for Spatial Information - CEOSpaceTech, University Politehnica of Bucharest, 313 Splaiul Independenţei, 061071 Bucharest, Romania
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84
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Krenn M, Malik M, Fickler R, Lapkiewicz R, Zeilinger A. Automated Search for new Quantum Experiments. PHYSICAL REVIEW LETTERS 2016; 116:090405. [PMID: 26991161 DOI: 10.1103/physrevlett.116.090405] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Indexed: 05/11/2023]
Abstract
Quantum mechanics predicts a number of, at first sight, counterintuitive phenomena. It therefore remains a question whether our intuition is the best way to find new experiments. Here, we report the development of the computer algorithm Melvin which is able to find new experimental implementations for the creation and manipulation of complex quantum states. Indeed, the discovered experiments extensively use unfamiliar and asymmetric techniques which are challenging to understand intuitively. The results range from the first implementation of a high-dimensional Greenberger-Horne-Zeilinger state, to a vast variety of experiments for asymmetrically entangled quantum states-a feature that can only exist when both the number of involved parties and dimensions is larger than 2. Additionally, new types of high-dimensional transformations are found that perform cyclic operations. Melvin autonomously learns from solutions for simpler systems, which significantly speeds up the discovery rate of more complex experiments. The ability to automate the design of a quantum experiment can be applied to many quantum systems and allows the physical realization of quantum states previously thought of only on paper.
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Affiliation(s)
- Mario Krenn
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Mehul Malik
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Robert Fickler
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Radek Lapkiewicz
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Anton Zeilinger
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
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85
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Experimental violation of Bell inequalities for multi-dimensional systems. Sci Rep 2016; 6:22088. [PMID: 26917246 PMCID: PMC4768136 DOI: 10.1038/srep22088] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/05/2016] [Indexed: 11/28/2022] Open
Abstract
Quantum correlations between spatially separated parts of a d-dimensional bipartite system (d ≥ 2) have no classical analog. Such correlations, also called entanglements, are not only conceptually important, but also have a profound impact on information science. In theory the violation of Bell inequalities based on local realistic theories for d-dimensional systems provides evidence of quantum nonlocality. Experimental verification is required to confirm whether a quantum system of extremely large dimension can possess this feature, however it has never been performed for large dimension. Here, we report that Bell inequalities are experimentally violated for bipartite quantum systems of dimensionality d = 16 with the usual ensembles of polarization-entangled photon pairs. We also estimate that our entanglement source violates Bell inequalities for extremely high dimensionality of d > 4000. The designed scenario offers a possible new method to investigate the entanglement of multipartite systems of large dimensionality and their application in quantum information processing.
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86
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Hiesmayr BC, de Dood MJA, Löffler W. Observation of Four-Photon Orbital Angular Momentum Entanglement. PHYSICAL REVIEW LETTERS 2016; 116:073601. [PMID: 26943533 DOI: 10.1103/physrevlett.116.073601] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Indexed: 05/14/2023]
Abstract
We demonstrate genuine multipartite quantum entanglement of four photons in their orbital angular momentum degrees of freedom, where a high-dimensional discrete Hilbert space is attached to each photon. This can encode more quantum information compared to the qubit case, but it is a long-standing problem to entangle more than two such photons. In our experiment we use pulsed spontaneous parametric down-conversion to produce the photon quadruplets, which allows us to detect about one four-photon event per second. By means of quantum state reconstruction and a suitable witness operator we find that the photon quadruplets form a genuine multipartite entangled symmetric Dicke state. This opens a new tool for addressing foundational questions in quantum mechanics, and for exploration of novel high-dimensional multiparty quantum information applications such as secret sharing.
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Affiliation(s)
- B C Hiesmayr
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - M J A de Dood
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - W Löffler
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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87
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Deterministic error correction for nonlocal spatial-polarization hyperentanglement. Sci Rep 2016; 6:20677. [PMID: 26861681 PMCID: PMC4748264 DOI: 10.1038/srep20677] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 12/30/2015] [Indexed: 11/24/2022] Open
Abstract
Hyperentanglement is an effective quantum source for quantum communication network due to its high capacity, low loss rate, and its unusual character in teleportation of quantum particle fully. Here we present a deterministic error-correction scheme for nonlocal spatial-polarization hyperentangled photon pairs over collective-noise channels. In our scheme, the spatial-polarization hyperentanglement is first encoded into a spatial-defined time-bin entanglement with identical polarization before it is transmitted over collective-noise channels, which leads to the error rejection of the spatial entanglement during the transmission. The polarization noise affecting the polarization entanglement can be corrected with a proper one-step decoding procedure. The two parties in quantum communication can, in principle, obtain a nonlocal maximally entangled spatial-polarization hyperentanglement in a deterministic way, which makes our protocol more convenient than others in long-distance quantum communication.
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88
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Direct measurement of large-scale quantum states via expectation values of non-Hermitian matrices. Nat Commun 2016; 7:10439. [PMID: 26780858 PMCID: PMC4735685 DOI: 10.1038/ncomms10439] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 12/10/2015] [Indexed: 11/26/2022] Open
Abstract
In quantum mechanics, predictions are made by way of calculating expectation values of observables, which take the form of Hermitian operators. Non-Hermitian operators, however, are not necessarily devoid of physical significance, and they can play a crucial role in the characterization of quantum states. Here we show that the expectation values of a particular set of non-Hermitian matrices, which we call column operators, directly yield the complex coefficients of a quantum state vector. We provide a definition of the state vector in terms of measurable quantities by decomposing these column operators into observables. The technique we propose renders very-large-scale quantum states significantly more accessible in the laboratory, as we demonstrate by experimentally characterizing a 100,000-dimensional entangled state. This represents an improvement of two orders of magnitude with respect to previous phase-and-amplitude characterizations of discrete entangled states. Quantum state tomography is the process of retrieving the values that define a quantum system, but realizing it experimentally can be burdensome. Here, the authors provide an alternative approach via the expectation values of a set of non-Hermitian matrices, and characterize a 100,000-dimensional state.
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89
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Abstract
Photons with a twisted phase front can carry a discrete, in principle, unbounded amount of orbital angular momentum (OAM). The large state space allows for complex types of entanglement, interesting both for quantum communication and for fundamental tests of quantum theory. However, the distribution of such entangled states over large distances was thought to be infeasible due to influence of atmospheric turbulence, indicating a serious limitation on their usefulness. Here we show that it is possible to distribute quantum entanglement encoded in OAM over a turbulent intracity link of 3 km. We confirm quantum entanglement of the first two higher-order levels (with OAM=± 1ħ and ± 2ħ). They correspond to four additional quantum channels orthogonal to all that have been used in long-distance quantum experiments so far. Therefore, a promising application would be quantum communication with a large alphabet. We also demonstrate that our link allows access to up to 11 quantum channels of OAM. The restrictive factors toward higher numbers are technical limitations that can be circumvented with readily available technologies.
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90
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Lantz E, Denis S, Moreau PA, Devaux F. Einstein-Podolsky-Rosen paradox in single pairs of images. OPTICS EXPRESS 2015; 23:26472-26478. [PMID: 26480160 DOI: 10.1364/oe.23.026472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Spatially entangled twin photons provide a test of the Einstein-Podolsky-Rosen (EPR) paradox in its original form of position (image plane) versus impulsion (Fourier plane). We show that recording a single pair of images in each plane is sufficient to safely demonstrate an EPR paradox. On each pair of images, we have retrieved the fluctuations by subtracting the fitted deterministic intensity shape and then have obtained an intercorrelation peak with a sufficient signal to noise ratio to safely distinguish this peak from random fluctuations. A 95% confidence interval has been determined, confirming a high degree of paradox whatever the considered single pairs. Last, we have verified that the value of the variance of the difference between twin images is always below the quantum (poissonian) limit, in order to ensure the particle character of the demonstration. Our demonstration shows that a single image pattern can reveal the quantum and non-local behavior of light.
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91
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Goyeneche D, Cañas G, Etcheverry S, Gómez ES, Xavier GB, Lima G, Delgado A. Five Measurement Bases Determine Pure Quantum States on Any Dimension. PHYSICAL REVIEW LETTERS 2015; 115:090401. [PMID: 26371631 DOI: 10.1103/physrevlett.115.090401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Indexed: 06/05/2023]
Abstract
A long-standing problem in quantum mechanics is the minimum number of observables required for the characterization of unknown pure quantum states. The solution to this problem is especially important for the developing field of high-dimensional quantum information processing. In this work we demonstrate that any pure d-dimensional state is unambiguously reconstructed by measuring five observables, that is, via projective measurements onto the states of five orthonormal bases. Thus, in our method the total number of different measurement outcomes (5d) scales linearly with d. The state reconstruction is robust against experimental errors and requires simple postprocessing, regardless of d. We experimentally demonstrate the feasibility of our scheme through the reconstruction of eight-dimensional quantum states, encoded in the momentum of single photons.
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Affiliation(s)
- D Goyeneche
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - G Cañas
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - S Etcheverry
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - E S Gómez
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - G B Xavier
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción, 160-C Concepción, Chile
| | - G Lima
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - A Delgado
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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92
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Zhou ZY, Li Y, Ding DS, Zhang W, Shi S, Shi BS. Classical to quantum optical network link for orbital angular momentum-carrying light. OPTICS EXPRESS 2015; 23:18435-18444. [PMID: 26191902 DOI: 10.1364/oe.23.018435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using orbital angular momentum (OAM) conservation in second-order nonlinear interaction processes, we create a classical to quantum optical network link in the OAM degrees of freedom of light via sum frequency generation, followed by spontaneous parametric down-conversion. Coherent OAM-carrying beams at 1550 nm are up-converted to 525.5-nm OAM-carrying beams in the first crystal, and are used to pump a second crystal to generate non-degenerate OAM entangled photon pairs at 795 nm and 1550 nm. By switching the OAM carried by the classical part, OAM correlation in the quantum part is shifted. High-level OAM entanglements in two-dimensional subspaces are verified.
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93
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Quantum simulation of 2D topological physics in a 1D array of optical cavities. Nat Commun 2015; 6:7704. [PMID: 26145177 PMCID: PMC4506549 DOI: 10.1038/ncomms8704] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/01/2015] [Indexed: 11/14/2022] Open
Abstract
Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration. A wide variety of interesting phenomena arise in 2D systems subject to external gauge fields, but these are sometimes challenging to verify experimentally. Here the authors propose a setup to simulate 2D physics with a 1D arrangement of cavities, by exploiting the orbital angular momentum of trapped photons.
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94
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Ding DS, Zhang W, Zhou ZY, Shi S, Xiang GY, Wang XS, Jiang YK, Shi BS, Guo GC. Quantum storage of orbital angular momentum entanglement in an atomic ensemble. PHYSICAL REVIEW LETTERS 2015; 114:050502. [PMID: 25699427 DOI: 10.1088/1361-6455/aa9b95] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Indexed: 05/28/2023]
Abstract
Constructing a quantum memory for a photonic entanglement is vital for realizing quantum communication and network. Because of the inherent infinite dimension of orbital angular momentum (OAM), the photon's OAM has the potential for encoding a photon in a high-dimensional space, enabling the realization of high channel capacity communication. Photons entangled in orthogonal polarizations or optical paths had been stored in a different system, but there have been no reports on the storage of a photon pair entangled in OAM space. Here, we report the first experimental realization of storing an entangled OAM state through the Raman protocol in a cold atomic ensemble. We reconstruct the density matrix of an OAM entangled state with a fidelity of 90.3%±0.8% and obtain the Clauser-Horne-Shimony-Holt inequality parameter S of 2.41±0.06 after a programed storage time. All results clearly show the preservation of entanglement during the storage.
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Affiliation(s)
- Dong-Sheng Ding
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Zhang
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhi-Yuan Zhou
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shuai Shi
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guo-Yong Xiang
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xi-Shi Wang
- State Key Laboratory of Fire Science, University of Science & Technology of China, Hefei, Anhui 230026, China
| | - Yun-Kun Jiang
- College of Physics and Information Engineering, Fuzhou University, Fuzhou 350002, People's Republic of China
| | - Bao-Sen Shi
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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95
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Moreau PA, Devaux F, Lantz E. Einstein-Podolsky-Rosen paradox in twin images. PHYSICAL REVIEW LETTERS 2014; 113:160401. [PMID: 25361237 DOI: 10.1103/physrevlett.113.160401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Indexed: 05/05/2023]
Abstract
Spatially entangled twin photons provide both promising resources for modern quantum information protocols, because of the high dimensionality of transverse entanglement, and a test of the Einstein-Podolsky-Rosen paradox in its original form of position versus impulsion. Usually, photons in temporal coincidence are selected and their positions recorded, resulting in a priori assumptions on their spatiotemporal behavior. In this Letter, we record, on two separate electron-multiplying charge coupled devices cameras, twin images of the entire flux of spontaneous down-conversion. This ensures a strict equivalence between the subsystems corresponding to the detection of either position (image or near-field plane) or momentum (Fourier or far-field plane). We report the highest degree of paradox ever reported and show that this degree corresponds to the number of independent degrees of freedom, or resolution cells, of the images.
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Affiliation(s)
- Paul-Antoine Moreau
- Département d'Optique, Institut FEMTO-ST, Université de Franche-Comté, CNRS, 25000 Besançon, France
| | - Fabrice Devaux
- Département d'Optique, Institut FEMTO-ST, Université de Franche-Comté, CNRS, 25000 Besançon, France
| | - Eric Lantz
- Département d'Optique, Institut FEMTO-ST, Université de Franche-Comté, CNRS, 25000 Besançon, France
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96
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97
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Huber M, Sengupta R. Witnessing genuine multipartite entanglement with positive maps. PHYSICAL REVIEW LETTERS 2014; 113:100501. [PMID: 25238339 DOI: 10.1103/physrevlett.113.100501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Indexed: 06/03/2023]
Abstract
We derive a general framework that lifts any set of bipartite to multipartite entanglement witnesses and we show how positive maps can naturally be incorporated into this framework. We show that some previous approaches for multipartite entanglement detection are intimately connected to the witnesses derived from partial transposition and that such criteria can easily be outperformed in higher dimensions by nondecomposable maps. As an exemplary case we present a witness that is capable of detecting genuine multipartite entanglement in bound entangled states.
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Affiliation(s)
- Marcus Huber
- ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona, Spain and Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Ritabrata Sengupta
- Department of Mathematical Sciences, Indian Institute of Science Education and Research Mohali, Mohali 140306, India and Theoretical Statistics and Mathematics Unit, Indian Statistical Institute, 7 S.J.S. Sansanwal Marg, New Delhi 110 016, India
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98
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Fickler R, Lapkiewicz R, Huber M, Lavery MP, Padgett MJ, Zeilinger A. Interface between path and orbital angular momentum entanglement for high-dimensional photonic quantum information. Nat Commun 2014; 5:4502. [DOI: 10.1038/ncomms5502] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 06/25/2014] [Indexed: 11/09/2022] Open
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99
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Practical bound for dimensionality in high-dimensional entanglement. Proc Natl Acad Sci U S A 2014; 111:6122-3. [PMID: 24737892 DOI: 10.1073/pnas.1404903111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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