1
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Dowling E, Morris M, Baumgartner G, Roy R, Murphy TE. Non-local polarization alignment and control in fibers using feedback from correlated measurements of entangled photons. OPTICS EXPRESS 2023; 31:2316-2329. [PMID: 36785248 DOI: 10.1364/oe.475465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/21/2022] [Indexed: 06/18/2023]
Abstract
Quantum measurements that use the entangled photons' polarization to encode quantum information require calibration and alignment of the measurement bases between spatially separate observers. Because of the changing birefringence in optical fibers arising from temperature fluctuations or external mechanical vibrations, the polarization state at the end of a fiber channel is unpredictable and time-varying. Polarization tracking and stabilization methods originally developed for classical optical communications cannot be applied to polarization-entangled photons, where the separately detected photons are statistically unpolarized, yet quantum mechanically correlated. We report here a fast method for automatic alignment and dynamic tracking of the polarization measurement bases between spatially separated detectors. The system uses the Nelder-Mead simplex method to minimize the observed coincidence rate between non-locally measured entangled photon pairs, without relying on classical wavelength-multiplexed pilot tones or temporally interleaved polarized photons. Alignment and control is demonstrated in a 7.1 km deployed fiber loop as well as in a controlled drifting scenario.
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2
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Alnas J, Alshowkan M, Rao NSV, Peters NA, Lukens JM. Optimal resource allocation for flexible-grid entanglement distribution networks. OPTICS EXPRESS 2022; 30:24375-24393. [PMID: 36236994 DOI: 10.1364/oe.458358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/10/2022] [Indexed: 06/16/2023]
Abstract
We use a genetic algorithm (GA) as a design aid for determining the optimal provisioning of entangled photon spectrum in flex-grid quantum networks with arbitrary numbers of channels and users. After introducing a general model for entanglement distribution based on frequency-polarization hyperentangled biphotons, we derive upper bounds on fidelity and entangled bit rate for networks comprising one-to-one user connections. Simple conditions based on user detector quality and link efficiencies are found that determine whether entanglement is possible. We successfully apply a GA to find optimal resource allocations in four different representative network scenarios and validate features of our model experimentally in a quantum local area network in deployed fiber. Our results show promise for the rapid design of large-scale entanglement distribution networks.
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3
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Zeuner KD, Jöns KD, Schweickert L, Reuterskiöld Hedlund C, Nuñez Lobato C, Lettner T, Wang K, Gyger S, Schöll E, Steinhauer S, Hammar M, Zwiller V. On-Demand Generation of Entangled Photon Pairs in the Telecom C-Band with InAs Quantum Dots. ACS PHOTONICS 2021; 8:2337-2344. [PMID: 34476289 PMCID: PMC8377713 DOI: 10.1021/acsphotonics.1c00504] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Indexed: 06/13/2023]
Abstract
Entangled photons are an integral part in quantum optics experiments and a key resource in quantum imaging, quantum communication, and photonic quantum information processing. Making this resource available on-demand has been an ongoing scientific challenge with enormous progress in recent years. Of particular interest is the potential to transmit quantum information over long distances, making photons the only reliable flying qubit. Entangled photons at the telecom C-band could be directly launched into single-mode optical fibers, enabling worldwide quantum communication via existing telecommunication infrastructure. However, the on-demand generation of entangled photons at this desired wavelength window has been elusive. Here, we show a photon pair generation efficiency of 69.9 ± 3.6% in the telecom C-band by an InAs/GaAs semiconductor quantum dot on a metamorphic buffer layer. Using a robust phonon-assisted two-photon excitation scheme we measure a maximum concurrence of 91.4 ± 3.8% and a peak fidelity to the Φ+ state of 95.2 ± 1.1%, verifying on-demand generation of strongly entangled photon pairs and marking an important milestone for interfacing quantum light sources with our classical fiber networks.
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Affiliation(s)
- Katharina D. Zeuner
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Klaus D. Jöns
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Lucas Schweickert
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Carl Reuterskiöld Hedlund
- Department
of Electrical Engineering, Royal Institute
of Technology, Electrum 229, 164 40 Kista, Sweden
| | - Carlos Nuñez Lobato
- Department
of Electrical Engineering, Royal Institute
of Technology, Electrum 229, 164 40 Kista, Sweden
| | - Thomas Lettner
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Kai Wang
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Samuel Gyger
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Eva Schöll
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Stephan Steinhauer
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Mattias Hammar
- Department
of Electrical Engineering, Royal Institute
of Technology, Electrum 229, 164 40 Kista, Sweden
| | - Val Zwiller
- Department
of Applied Physics, Royal Institute of Technology,
Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
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4
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Anwar A, Perumangatt C, Steinlechner F, Jennewein T, Ling A. Entangled photon-pair sources based on three-wave mixing in bulk crystals. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:041101. [PMID: 34243479 DOI: 10.1063/5.0023103] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 03/01/2021] [Indexed: 06/13/2023]
Abstract
Entangled photon pairs are a critical resource in quantum communication protocols ranging from quantum key distribution to teleportation. The current workhorse technique for producing photon pairs is via spontaneous parametric down conversion (SPDC) in bulk nonlinear crystals. The increased prominence of quantum networks has led to a growing interest in deployable high performance entangled photon-pair sources. This manuscript provides a review of the state-of-the-art bulk-optics-based SPDC sources with continuous wave pump and discusses some of the main considerations when building for deployment.
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Affiliation(s)
- Ali Anwar
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, S117543 Singapore, Singapore
| | - Chithrabhanu Perumangatt
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, S117543 Singapore, Singapore
| | - Fabian Steinlechner
- Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Straße 7, 07745 Jena, Germany
| | - Thomas Jennewein
- Institute of Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
| | - Alexander Ling
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, S117543 Singapore, Singapore
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5
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Li Y, Huang Y, Xiang T, Nie Y, Sang M, Yuan L, Chen X. Multiuser Time-Energy Entanglement Swapping Based on Dense Wavelength Division Multiplexed and Sum-Frequency Generation. PHYSICAL REVIEW LETTERS 2019; 123:250505. [PMID: 31922812 DOI: 10.1103/physrevlett.123.250505] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Indexed: 06/10/2023]
Abstract
Perfect entanglement swapping, which can be realized without the postselection by using the nonlinear optical technology, provides an important way toward generating the large-scale quantum network. We explore an entanglement-swapping-based dense wavelength division multiplexed network in the experiment. Four users receive single quantum states at different wavelengths, and we perform a time-energy entanglement swapping operation based on the sum-frequency generation to make users fully connected in the network. The results show that the fidelity of the entangled state is larger than 90% and is independent of the number of users. Our Letter demonstrates the feasibility of a proposed multiuser network, and hence paves a route toward a variety of quantum applications, including entanglement-swapping-based quantum direct communication.
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Affiliation(s)
- Yuanhua Li
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
- Department of Physics, Jiangxi Normal University, Nanchang 330022, China
| | - Yiwen Huang
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Tong Xiang
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yiyou Nie
- Department of Physics, Jiangxi Normal University, Nanchang 330022, China
| | - Minghuang Sang
- Department of Physics, Jiangxi Normal University, Nanchang 330022, China
| | - Luqi Yuan
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Xianfeng Chen
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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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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7
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Distribution of entangled photon pairs over few-mode fibers. Sci Rep 2017; 7:14954. [PMID: 29097761 PMCID: PMC5668260 DOI: 10.1038/s41598-017-14955-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/18/2017] [Indexed: 11/29/2022] Open
Abstract
Few-mode fibers (FMFs) have been recently employed in classical optical communication to increase the data transmission capacity. Here we explore the capability of employing FMF for long distance quantum communication. We experimentally distribute photon pairs in the forms of time-bin and polarization entanglement over a 1-km-long FMF. We find the time-bin entangled photon pairs maintain their high degree of entanglement, no matter what type of spatial modes they are distributed in. For the polarization entangled photon pairs, however, the degree of entanglement is maintained when photon pairs are distributed in LP01 mode but significantly declines when photon pairs are distributed in LP11 mode due to a mode coupling effect in LP11 mode group. We propose and test a remedy to recover the high degree of entanglement. Our study shows, when FMFs are employed as quantum channels, selection of spatial channels and degrees of freedom of entanglement should be carefully considered.
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8
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Liu WY, Zhong XF, Wu T, Li FZ, Jin B, Tang Y, Hu HM, Li ZP, Zhang L, Cai WQ, Liao SK, Cao Y, Peng CZ. Experimental free-space quantum key distribution with efficient error correction. OPTICS EXPRESS 2017; 25:10716-10723. [PMID: 28788761 DOI: 10.1364/oe.25.010716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report a 17-km free-space quantum key distribution (QKD) experiment using an engineering model of the space-bound optical transmitter and a ground station for satellite-ground QKD. The final key rate of ~ 0.5 kbps is achieved in this experiment with the quantum bit error rate (QBER) of ~ 3.4%. An efficient error correction algorithm, Turbo Code, is employed. Compared with the current error correction algorithm of Cascade, a high-efficiency error correction is realized by Turbo Code with only one-time data exchange. For a low QBER, with only one-time data exchange, the final key rates based on Turbo code are similar with Cascade. As the QBER increases, Turbo Code gives higher final key rates than Cascade. Our results experimentally demonstrate the feasibility of satellite-ground QKD and show that the efficient error correction based on Turbo Code is potentially useful for the satellite-ground quantum communication.
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9
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Chun H, Choi I, Faulkner G, Clarke L, Barber B, George G, Capon C, Niskanen A, Wabnig J, O'Brien D, Bitauld D. Handheld free space quantum key distribution with dynamic motion compensation. OPTICS EXPRESS 2017; 25:6784-6795. [PMID: 28381021 DOI: 10.1364/oe.25.006784] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Mobile devices have become an inseparable part of our everyday life. They are used to transmit an ever-increasing amount of sensitive health, financial and personal information. This exposes us to the growing scale and sophistication of cyber-attacks. Quantum Key Distribution (QKD) can provide unconditional and future-proof data security but implementing it for handheld mobile devices comes with specific challenges. To establish security, secret keys of sufficient length need to be transmitted during the time of a handheld transaction (~1s) despite device misalignment, ambient light and user's inevitable hand movements. Transmitters and receivers should ideally be compact and low-cost, while avoiding security loopholes. Here we demonstrate the first QKD transmission from a handheld transmitter with a key-rate large enough to overcome finite key effects. Using dynamic beam-steering, reference-frame-independent encoding and fast indistinguishable pulse generation, we obtain a secret key rate above 30kb/s over a distance of 0.5m.
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10
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Arahira S, Murai H, Sasaki H. Generation of highly stable WDM time-bin entanglement by cascaded sum-frequency generation and spontaneous parametric downconversion in a PPLN waveguide device. OPTICS EXPRESS 2016; 24:19581-19591. [PMID: 27557236 DOI: 10.1364/oe.24.019581] [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
In this paper we report the generation of wavelength-division-multiplexed, time-bin entangled photon pairs by using cascaded optical second nonlinearities (sum-frequency generation and subsequent spontaneous parametric downconversion) in a periodically poled LiNbO3 device. Visibilities of approximately 94% were clearly observed in two-photon interference experiments for all the wavelength-multiplexed channels under investigation (five pairs), with insensitivity to the polarization states of the photon pairs. We also evaluated the performances in terms of quantum-key-distribution (QKD) applications by using four single-photon detectors, which enables to evaluate the QKD performance properly. The results showed long-term stability over 70 hours, maintaining approximately 3% of the quantum error rate and 110 bit/s of the sifted key rate.
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11
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GAZZANO OLIVIER, SOLOMON GLENNS. Toward optical quantum information processing with quantum dots coupled to microstructures [Invited]. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. B, OPTICAL PHYSICS 2016; 33:10.1364/josab.33.00c160. [PMID: 38881569 PMCID: PMC11177888 DOI: 10.1364/josab.33.00c160] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Major improvements have been made on semiconductor quantum dot light sources recently and now they can be seen as a serious candidate for near-future scalable photonic quantum information processing experiments. The three key parameters of these photon sources for such applications have been pushed to extreme values: almost unity single-photon purity and photon indistinguishability, and high brightness. In this paper, we review the progress achieved recently on quantum-dot-based single-photon sources. We also review some quantum information experiments where entanglement processes are achieved using semiconductor quantum dots.
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Affiliation(s)
- OLIVIER GAZZANO
- Joint Quantum Institute, National Institute of Standards and Technology & University of Maryland, Gaithersburg, Maryland 20899,USA
| | - GLENN S. SOLOMON
- Joint Quantum Institute, National Institute of Standards and Technology & University of Maryland, Gaithersburg, Maryland 20899,USA
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12
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Carvacho G, Cariñe J, Saavedra G, Cuevas Á, Fuenzalida J, Toledo F, Figueroa M, Cabello A, Larsson JÅ, Mataloni P, Lima G, Xavier GB. Postselection-Loophole-Free Bell Test Over an Installed Optical Fiber Network. PHYSICAL REVIEW LETTERS 2015; 115:030503. [PMID: 26230776 DOI: 10.1103/physrevlett.115.030503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Indexed: 06/04/2023]
Abstract
Device-independent quantum communication will require a loophole-free violation of Bell inequalities. In typical scenarios where line of sight between the communicating parties is not available, it is convenient to use energy-time entangled photons due to intrinsic robustness while propagating over optical fibers. Here we show an energy-time Clauser-Horne-Shimony-Holt Bell inequality violation with two parties separated by 3.7 km over the deployed optical fiber network belonging to the University of Concepción in Chile. Remarkably, this is the first Bell violation with spatially separated parties that is free of the postselection loophole, which affected all previous in-field long-distance energy-time experiments. Our work takes a further step towards a fiber-based loophole-free Bell test, which is highly desired for secure quantum communication due to the widespread existing telecommunication infrastructure.
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Affiliation(s)
- Gonzalo Carvacho
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Jaime Cariñe
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción,160-C Concepción, Chile
| | - Gabriel Saavedra
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción,160-C Concepción, Chile
| | - Álvaro Cuevas
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Jorge Fuenzalida
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Felipe Toledo
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Miguel Figueroa
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción,160-C Concepción, Chile
| | - Adán Cabello
- Departamento de Física Aplicada II, Universidad de Sevilla, E-41012 Sevilla, Spain
| | - Jan-Åke Larsson
- Institutionen för Systemteknik, Linköpings Universitet, 581 83 Linköping, Sweden
| | - Paolo Mataloni
- Dipartimento de Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, Roma I-00185, Italy
| | - Gustavo Lima
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Guilherme B Xavier
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción,160-C Concepción, Chile
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13
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Zhong M, Hedges MP, Ahlefeldt RL, Bartholomew JG, Beavan SE, Wittig SM, Longdell JJ, Sellars MJ. Optically addressable nuclear spins in a solid with a six-hour coherence time. Nature 2015; 517:177-80. [DOI: 10.1038/nature14025] [Citation(s) in RCA: 395] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 10/28/2014] [Indexed: 11/09/2022]
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14
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Jayakumar H, Predojević A, Kauten T, Huber T, Solomon GS, Weihs G. Time-bin entangled photons from a quantum dot. Nat Commun 2014; 5:4251. [PMID: 24968024 PMCID: PMC4108004 DOI: 10.1038/ncomms5251] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 05/29/2014] [Indexed: 11/09/2022] Open
Abstract
Long-distance quantum communication is one of the prime goals in the field of quantum information science. With information encoded in the quantum state of photons, existing telecommunication fibre networks can be effectively used as a transport medium. To achieve this goal, a source of robust entangled single-photon pairs is required. Here we report the realization of a source of time-bin entangled photon pairs utilizing the biexciton-exciton cascade in a III/V self-assembled quantum dot. We analyse the generated photon pairs by an inherently phase-stable interferometry technique, facilitating uninterrupted long integration times. We confirm the entanglement by performing quantum state tomography of the emitted photons, which yields a fidelity of 0.69(3) and a concurrence of 0.41(6) for our realization of time-energy entanglement from a single quantum emitter.
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Affiliation(s)
- Harishankar Jayakumar
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Ana Predojević
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Thomas Kauten
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Tobias Huber
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Glenn S Solomon
- Joint Quantum Institute, National Institute of Standards and Technology & University of Maryland, Gaithersburg, Maryland 20849, USA
| | - Gregor Weihs
- 1] Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria [2] Institute for Quantum Computing, University of Waterloo, 200 University Ave W, Waterloo, Ontario, Canada N2L 3G1
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15
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Guo Q, Cheng LY, Chen L, Wang HF, Zhang S. Counterfactual entanglement distribution without transmitting any particles. OPTICS EXPRESS 2014; 22:8970-8984. [PMID: 24787786 DOI: 10.1364/oe.22.008970] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To date, all schemes for entanglement distribution needed to send entangled particles or a separable mediating particle among distant participants. Here, we propose a counterfactual protocol for entanglement distribution against the traditional forms, that is, two distant particles can be entangled with no physical particles travel between the two remote participants. We also present an alternative scheme for realizing the counterfactual photonic entangled state distribution using Michelson-type interferometer and self-assembled GaAs/InAs quantum dot embedded in a optical microcavity. The numerical analysis about the effect of experimental imperfections on the performance of the scheme shows that the entanglement distribution may be implementable with high fidelity.
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16
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Kwon O, Park KK, Ra YS, Kim YS, Kim YH. Time-bin entangled photon pairs from spontaneous parametric down-conversion pumped by a cw multi-mode diode laser. OPTICS EXPRESS 2013; 21:25492-25500. [PMID: 24150388 DOI: 10.1364/oe.21.025492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Generation of time-bin entangled photon pairs requires the use of the Franson interferometer which consists of two spatially separated unbalanced Mach-Zehnder interferometers through which the signal and idler photons from spontaneous parametric down-conversion (SPDC) are made to transmit individually. There have been two SPDC pumping regimes where the scheme works: the narrowband regime and the double-pulse regime. In the narrowband regime, the SPDC process is pumped by a narrowband cw laser with the coherence length much longer than the path length difference of the Franson interferometer. In the double-pulse regime, the longitudinal separation between the pulse pair is made equal to the path length difference of the Franson interferometer. In this paper, we propose another regime by which the generation of time-bin entanglement is possible and demonstrate the scheme experimentally. In our scheme, differently from the previous approaches, the SPDC process is pumped by a cw multi-mode (i.e., short coherence length) laser and makes use of the coherence revival property of such a laser. The high-visibility two-photon Franson interference demonstrates clearly that high-quality time-bin entanglement source can be developed using inexpensive cw multi-mode diode lasers for various quantum communication applications.
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17
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Inagaki T, Matsuda N, Tadanaga O, Asobe M, Takesue H. Entanglement distribution over 300 km of fiber. OPTICS EXPRESS 2013; 21:23241-23249. [PMID: 24104238 DOI: 10.1364/oe.21.023241] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report the distribution of time-bin entangled photon pairs over 300 km of optical fiber. We realized this by using a high-speed and high signal-to-noise ratio entanglement generation/evaluation setup that consists of periodically poled lithium niobate waveguides and superconducting single photon detectors. The observed two-photon interference fringes exhibited a visibility of 84%. We confirmed the violation of Bell's inequality by 2.9 standard deviations.
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18
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Jayakumar H, Predojević A, Huber T, Kauten T, Solomon GS, Weihs G. Deterministic photon pairs and coherent optical control of a single quantum dot. PHYSICAL REVIEW LETTERS 2013; 110:135505. [PMID: 23581338 DOI: 10.1103/physrevlett.110.135505] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Indexed: 06/02/2023]
Abstract
The strong confinement of semiconductor excitons in a quantum dot gives rise to atomlike behavior. The full benefit of such a structure is best observed in resonant excitation where the excited state can be deterministically populated and coherently manipulated. Because of the large refractive index and device geometry it remains challenging to observe resonantly excited emission that is free from laser scattering in III/V self-assembled quantum dots. Here we exploit the biexciton binding energy to create an extremely clean single photon source via two-photon resonant excitation of an InAs/GaAs quantum dot. We observe complete suppression of the excitation laser and multiphoton emissions. Additionally, we perform full coherent control of the ground-biexciton state qubit and observe an extended coherence time using an all-optical echo technique. The deterministic coherent photon pair creation makes this system suitable for the generation of time-bin entanglement and experiments on the interaction of photons from dissimilar sources.
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Affiliation(s)
- Harishankar Jayakumar
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
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Arahira S, Murai H. Nearly degenerate wavelength-multiplexed polarization entanglement by cascaded optical nonlinearities in a PPLN ridge waveguide device. OPTICS EXPRESS 2013; 21:7841-7850. [PMID: 23546166 DOI: 10.1364/oe.21.007841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this paper we report the generation of wavelength-multiplexed polarization-entangled photon pairs in the 1.5-μm communication wavelength band by using cascaded optical second nonlinearities (sum-frequency generation and subsequent spontaneous parametric down-conversion, c-SFG/SPDC) in a periodically poled LiNbO(3) ridge waveguide device. The c-SFG/SPDC method makes it possible to fully use the broad spectral bandwidth of SPDC in nearly frequency-degenerate conditions, and can provide more than 50 pairs of wavelength channels for the entangled photon pairs in the 1.5-μm wavelength band, using only standard optical resources in the telecom field. Visibilities higher than 98% were clearly observed in two-photon interference fringes for all the wavelength channels under investigation (eight pairs). We further performed a detailed experimental investigation of the cross-talk characteristics and the impact of detuning the pump wavelengths.
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Affiliation(s)
- Shin Arahira
- Corporate Research & Development Center, Oki Electric Industry Co., Ltd., 1-16-8 Chuou, Warabi-shi, Saitama 335-8510, Japan.
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Yin J, Ren JG, Lu H, Cao Y, Yong HL, Wu YP, Liu C, Liao SK, Zhou F, Jiang Y, Cai XD, Xu P, Pan GS, Jia JJ, Huang YM, Yin H, Wang JY, Chen YA, Peng CZ, Pan JW. Quantum teleportation and entanglement distribution over 100-kilometre free-space channels. Nature 2012; 488:185-8. [PMID: 22874963 DOI: 10.1038/nature11332] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 06/15/2012] [Indexed: 11/09/2022]
Abstract
Transferring an unknown quantum state over arbitrary distances is essential for large-scale quantum communication and distributed quantum networks. It can be achieved with the help of long-distance quantum teleportation and entanglement distribution. The latter is also important for fundamental tests of the laws of quantum mechanics. Although quantum teleportation and entanglement distribution over moderate distances have been realized using optical fibre links, the huge photon loss and decoherence in fibres necessitate the use of quantum repeaters for larger distances. However, the practical realization of quantum repeaters remains experimentally challenging. Free-space channels, first used for quantum key distribution, offer a more promising approach because photon loss and decoherence are almost negligible in the atmosphere. Furthermore, by using satellites, ultra-long-distance quantum communication and tests of quantum foundations could be achieved on a global scale. Previous experiments have achieved free-space distribution of entangled photon pairs over distances of 600 metres (ref. 14) and 13 kilometres (ref. 15), and transfer of triggered single photons over a 144-kilometre one-link free-space channel. Most recently, following a modified scheme, free-space quantum teleportation over 16 kilometres was demonstrated with a single pair of entangled photons. Here we report quantum teleportation of independent qubits over a 97-kilometre one-link free-space channel with multi-photon entanglement. An average fidelity of 80.4 ± 0.9 per cent is achieved for six distinct states. Furthermore, we demonstrate entanglement distribution over a two-link channel, in which the entangled photons are separated by 101.8 kilometres. Violation of the Clauser-Horne-Shimony-Holt inequality is observed without the locality loophole. Besides being of fundamental interest, our results represent an important step towards a global quantum network. Moreover, the high-frequency and high-accuracy acquiring, pointing and tracking technique developed in our experiment can be directly used for future satellite-based quantum communication and large-scale tests of quantum foundations.
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Affiliation(s)
- Juan Yin
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
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Arahira S, Murai H. Experimental investigation in transmission performance of polarization-entangled photon-pairs generated by cascaded χ(2) processes over standard single-mode optical fibers. OPTICS EXPRESS 2012; 20:15336-15346. [PMID: 22772230 DOI: 10.1364/oe.20.015336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this paper we report experimental investigation in transmission performance over standard single-mode optical fibers (SMFs) of polarization-entangled photon-pairs in a 1.5-μm band generated by cascaded second-harmonic generation and spontaneous parametric down conversion (c-SHG/SPDC) from a periodically poled LiNbO(3) (PPLN) ridge-waveguide device. Clear two-photon interference fringes were observed even after the transmission over 140 km of the SMF spools, remaining small degradation in the visibilities of less than 3%. The performance was also investigated by using optical attenuators, instead of the SMF spools, to study the maximum reach of the distribution of the entanglement in terms of loss penalty. The results show that the quantum entanglement could be distributed even with 50 dB of the transmission loss with violation of Bell inequality by using the c-SHG/SPDC-based photon-pair source.
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Affiliation(s)
- Shin Arahira
- Corporate Research & Development Center, Oki Electric Industry Co., Ltd., 1-16-8 Chuou, Warabi-shi, Saitama 335-8510, Japan.
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