1
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Halder J, Rajabov A, Bassoli R, Fitzek FHP, Fettweis GP. Optimal routing and end-to-end entanglement distribution in quantum networks. Sci Rep 2024; 14:19262. [PMID: 39164396 PMCID: PMC11336113 DOI: 10.1038/s41598-024-70114-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 08/13/2024] [Indexed: 08/22/2024] Open
Abstract
Quantum networks are designed to transmit quantum bits (qubits) among quantum devices to enable new network resources for the applications. Entanglement distribution and entanglement swapping are fundamental procedures that are required in several network operations. However, they are probabilistic operations, which can lead to severe network performance degradation. This article investigates the engineering problem of resource allocation in quantum networks, considering factors like entanglement distribution probability, quantum memory characteristics, and fidelity. We model this as an optimization model to obtain an optimal solution. In particular, we formulate an integer linear programming (ILP) and develop a heuristic algorithm, aiming to minimize the number of required entangled qubit pairs (Bell pairs or EPR pairs) in any adjacent pair in the quantum network. Extensive simulations are performed to compare the performance of proposed ILP and heuristic. In all the cases, the heuristic produces a comparable solution to the optimal one. Simulation results ensure that the value of maximum utilized Bell pairs in a quantum network highly depends on the value of the probability of entangled pairs established, considering the time in the quantum memory besides the number of incoming requests.
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Affiliation(s)
- Joy Halder
- Vodafone Chair Mobile Communications Systems, Technische Universität Dresden, 01067, Dresden, Germany.
| | - Akhmadjon Rajabov
- Deutsche Telekom Chair of Communication Networks, Technische Universität Dresden, 01067, Dresden, Germany.
- Quantum Communication Networks (QCNets) Research Group, Technische Universität Dresden, Dresden, Germany.
| | - Riccardo Bassoli
- Deutsche Telekom Chair of Communication Networks, Technische Universität Dresden, 01067, Dresden, Germany
- Centre for Tactile Internet with Human-in-the-Loop (CeTI), Dresden, Germany
- Quantum Communication Networks (QCNets) Research Group, Technische Universität Dresden, Dresden, Germany
| | - Frank H P Fitzek
- Deutsche Telekom Chair of Communication Networks, Technische Universität Dresden, 01067, Dresden, Germany
- Centre for Tactile Internet with Human-in-the-Loop (CeTI), Dresden, Germany
| | - Gerhard P Fettweis
- Vodafone Chair Mobile Communications Systems, Technische Universität Dresden, 01067, Dresden, Germany
- Centre for Tactile Internet with Human-in-the-Loop (CeTI), Dresden, Germany
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2
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Kalaga JK, Kowalewska-Kudłaszyk A, Leoński W, Peřina J. Legget-Garg inequality for a two-mode entangled bosonic system. OPTICS EXPRESS 2024; 32:9946-9957. [PMID: 38571218 DOI: 10.1364/oe.513855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 02/08/2024] [Indexed: 04/05/2024]
Abstract
We discuss a model of two nonlinear quantum oscillators mutually coupled by linear interaction and continuously driven by external coherent excitation. For such a system, we analyze temporal correlations. We examine the violation of the Leggett-Garg inequality analysing various scenarios of measurements. These scenarios are based on the projection onto different Bell states. We show that the possibility of violation of the Leggett-Garg inequalities is associated with the use of different projectors.
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3
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Lu HH, Alshowkan M, Myilswamy KV, Weiner AM, Lukens JM, Peters NA. Generation and characterization of ultrabroadband polarization-frequency hyperentangled photons. OPTICS LETTERS 2023; 48:6031-6034. [PMID: 37966781 DOI: 10.1364/ol.503127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/17/2023] [Indexed: 11/16/2023]
Abstract
We generate ultrabroadband photon pairs entangled in both polarization and frequency bins through an all-waveguided Sagnac source covering the entire optical C- and L-bands (1530-1625 nm). We perform comprehensive characterization of high-fidelity states in multiple dense wavelength-division multiplexed channels, achieving full tomography of effective four-qubit systems. Additionally, leveraging the inherent high dimensionality of frequency encoding and our electro-optic measurement approach, we demonstrate the scalability of our system to higher dimensions, reconstructing states in a 36-dimensional Hilbert space consisting of two polarization qubits and two frequency-bin qutrits. Our findings hold potential significance for quantum networking, particularly dense coding and entanglement distillation in wavelength-multiplexed quantum networks.
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4
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Shubha SEU, Rahman MS, Mahdy M. Significant improvement of fidelity for encoded quantum bell pairs at long and short-distance communication along with generalized circuit. Heliyon 2023; 9:e19700. [PMID: 37809815 PMCID: PMC10558957 DOI: 10.1016/j.heliyon.2023.e19700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 10/10/2023] Open
Abstract
Quantum entanglement is a unique criterion of the quantum realm and an essential tool to secure quantum communication. Ensuring high-fidelity entanglement has always been a challenging task owing to interaction with the hostile channel environment created due to quantum noise and decoherence. Though several methods have been proposed, correcting almost all arbitrary errors is still a gigantic task. As one of the main contributions of this work, a new model for 'large distance communication' has been proposed, which may correct all bit flip errors or other errors quite extensively if proper encoding and subspace measurements are used. To achieve this purpose, at the very first step, the idea of differentiating the 'long-distance communication' and 'short-distance applications' has been introduced. Short-distance is determined by the maximum range of applying unitary control gates by the qubit technology. How the error correcting ability of Quantum codes change for short and long-distance application is investigated in this work, which was not explored in previous literatures as far as we know. At the beginning, we have applied stabilizer formalism and Repetition Code for decoding to distinguish the error correcting ability in long and short distance communication. Particularly for short-distance communication, it has been demonstrated that a 'properly encoded' bell state can identify all the bit flip, or phase flip errors with 100% accuracy theoretically. In contrast, if the bell states are used in long-distance communication, the error-detecting and correcting ability reduces at huge amounts. To increase the fidelity significantly and correct the errors quite extensively for long-distance communication, a new model based on classical communication protocol has been suggested. All the required circuits in these processes have been generalized for arbitrary (even) numbers of ancilla qubits during encoding. Proposed analytical results have also been verified with the Simulation results of IBM QISKIT QASM.
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Affiliation(s)
- Syed Emad Uddin Shubha
- Department of Electrical & Computer Engineering, North South University, Bashundhara, Dhaka, 1229, Bangladesh
| | - Md. Saifur Rahman
- Department of Electrical & Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - M.R.C. Mahdy
- Department of Electrical & Computer Engineering, North South University, Bashundhara, Dhaka, 1229, Bangladesh
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5
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Palma Torres L, Solís-Prosser MÁ, Jiménez O, Gómez ES, Delgado A. Optimal High-Dimensional Entanglement Concentration for Pure Bipartite Systems. MICROMACHINES 2023; 14:1207. [PMID: 37374791 DOI: 10.3390/mi14061207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 06/29/2023]
Abstract
Considering pure quantum states, entanglement concentration is the procedure where, from N copies of a partially entangled state, a single state with higher entanglement can be obtained. Obtaining a maximally entangled state is possible for N=1. However, the associated success probability can be extremely low when increasing the system's dimensionality. In this work, we study two methods to achieve a probabilistic entanglement concentration for bipartite quantum systems with a large dimensionality for N=1, regarding a reasonably good probability of success at the expense of having a non-maximal entanglement. Firstly, we define an efficiency function Q considering a tradeoff between the amount of entanglement (quantified by the I-Concurrence) of the final state after the concentration procedure and its success probability, which leads to solving a quadratic optimization problem. We found an analytical solution, ensuring that an optimal scheme for entanglement concentration can always be found in terms of Q. Finally, a second method was explored, which is based on fixing the success probability and searching for the maximum amount of entanglement attainable. Both ways resemble the Procrustean method applied to a subset of the most significant Schmidt coefficients but obtaining non-maximally entangled states.
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Affiliation(s)
- Lukas Palma Torres
- Departamento de Ciencias Físicas, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Avenida Francisco Salazar 01145, Temuco 4811230, Chile
| | - Miguel Ángel Solís-Prosser
- Departamento de Ciencias Físicas, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Avenida Francisco Salazar 01145, Temuco 4811230, Chile
| | - Omar Jiménez
- Centro de Óptica e Información Cuántica, Facultad de Ciencias, Universidad Mayor, Camino La Pirámide 5750, Huechuraba, Santiago 8580745, Chile
| | - Esteban S Gómez
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción 4070043, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, Casilla 160-C, Concepción 4070043, Chile
| | - Aldo Delgado
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción 4070043, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, Casilla 160-C, Concepción 4070043, Chile
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6
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Xin X, He S, Li Y, Li C. Nontraditional Deterministic Remote State Preparation Using a Non-Maximally Entangled Channel without Additional Quantum Resources. ENTROPY (BASEL, SWITZERLAND) 2023; 25:e25050768. [PMID: 37238523 DOI: 10.3390/e25050768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/19/2023] [Accepted: 04/29/2023] [Indexed: 05/28/2023]
Abstract
In this paper, we have reinvestigated probabilistic quantum communication protocols and developed a nontraditional remote state preparation protocol that allows for deterministically transferring information encoded in quantum states using a non-maximally entangled channel. With an auxiliary particle and a simple measurement method, the success probability of preparing a d-dimensional quantum state is increased to 1 without spending additional quantum resources in advance to improve quantum channels, such as entanglement purification. Furthermore, we have designed a feasible experimental scheme to demonstrate the deterministic paradigm of transporting a polarization-encoded photon from one location to another using a generalized entangled state. This approach provides a practical method to address decoherence and environmental noises in actual quantum communication.
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Affiliation(s)
- Xuanxuan Xin
- School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Shiwen He
- School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Yongxing Li
- School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Chong Li
- School of Physics, Dalian University of Technology, Dalian 116024, China
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7
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Jiang L, Li Z, Li T. Nonlocal generalized quantum measurement of product observables with mixed entanglement. OPTICS EXPRESS 2023; 31:12508-12519. [PMID: 37157409 DOI: 10.1364/oe.487883] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Nonlocal observables of spacelike separated quantum systems in combination with their measurements contribute greatly to quantum theory and its applications. We present a nonlocal generalized quantum measurement protocol for measuring product observables, assisted by a meter in a mixed entangled state rather than maximally or partially entangled pure states. By tuning the entanglement of the meter, measurement strength of arbitrary values can be achieved for nonlocal product observables, since measurement strength equals the concurrence of the meter. Furthermore, we present a specific scheme to measure the polarization of two nonlocal photons using linear optics. We refer to the polarization and spatial-mode degrees of freedom of the same photon pair as the system and the meter, respectively, which significantly simplifies the interaction between the system and the meter. This protocol can be useful for applications involving nonlocal product observables and nonlocal weak values, and for tests of quantum foundations in nonlocal scenarios.
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8
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Jiang GL, Liu WQ, Wei HR. Heralded and high-efficient entanglement concentrations based on linear optics assisted by time-delay degree of freedom. OPTICS EXPRESS 2022; 30:47836-47846. [PMID: 36558702 DOI: 10.1364/oe.476342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Entanglement concentration is a critical technique to prevent degraded fidelity and security in long-distance quantum communication. We propose novel practical entanglement concentration protocols (ECPs) for less-entangled Bell and Greenberger-Horne-Zeilinger states with unknown parameters by solely using simple linear optics. We avoid the need for the post-selection principles or photon-number-resolving detectors to identify the parity-check measurement completely by orchestrating auxiliary time degree of freedom, and the success of ECPs is exactly heralded by the detection signatures without destroying the incident qubits. Additionally, the outting incident photons kept are in the maximally entangled or the less-entangled state, and the success probability can be increased by recycling the latter. The heralded and the basic linear optical elements make our practical ECPs are accessible to experimental investigation with current technology.
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9
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Wang S, Han XH, Li WC, Qian T, Fan X, Xiao Y, Gu YJ. Protecting nonlocal quantum correlations in correlated squeezed generalized amplitude damping channel. Sci Rep 2022; 12:20481. [PMID: 36443637 PMCID: PMC9705301 DOI: 10.1038/s41598-022-24789-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/21/2022] [Indexed: 11/29/2022] Open
Abstract
Nonlocal quantum correlations, such as quantum entanglement, quantum steering, and Bell nonlocality, are crucial resources for quantum information tasks. How to protect these quantum resources from decoherence is one of the most urgent problems to be solved. Here, we investigate the evolution of these correlations in the correlated squeezed generalized amplitude damping (SGAD) channel and propose a scheme to protect them with weak measurement (WM) and quantum measurement reversal (QMR). Compared with the results of the uncorrelated SGAD channel, we find that when [Formula: see text], correlation and squeezing effects can prolong the survival time of quantum entanglement, Bell nonlocality, and quantum steering by about 152 times, 207 times, and 10 times, respectively. In addition, local WM and QMR can effectively recover the disappeared nonlocal quantum correlations either in uncorrelated or completely correlated SGAD channels. Moreover, we find that these initial nonlocal quantum correlations could be drastically amplified under the correlated channel. And the steering direction can be flexibly manipulated either by changing the channel parameters or the strength of WM and QMR. These results not only make a step forward in suppressing decoherence and enhancing quantum correlation in noise channels, but also help to develop relevant practical applications.
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Affiliation(s)
- Shuo Wang
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China
| | - Xin-Hong Han
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China
| | - Wei-Chen Li
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China
| | - Tian Qian
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China
| | - Xuan Fan
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China
| | - Ya Xiao
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China.
| | - Yong-Jian Gu
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China.
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10
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Cheng WD, Lin CS, Zhang H, Chai GL. Computational Study of Dynamic Susceptibility and Phase-Matching Angle by Two-Photon Entangled Generation. J Phys Chem A 2022; 126:7787-7793. [PMID: 36240026 DOI: 10.1021/acs.jpca.2c05300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two-photon entangled generation is used to produce an entangled photon source which is a key and core element concerning the technology applications of quantum computing, quantum communication, and quantum precision measurement. In this work, we have deduced the formulas of dynamic susceptibility and phase-matching angle of two-photon entangled generation in nonlinear optical crystals. The formulas are employed to compute the susceptibilities and phase-matching angles of these optical processes for uniaxial and biaxial crystals. The susceptibility magnitude and phase-matching condition of two-photon entangled generation affect the performance of the source. The calculated results by these formulas are employed to study properties and estimate the performance of an entangled photon source. In this way, we discuss the phase matching among waves and working wavelength in an entangled source that affects the efficiency of satellite communication with the ground during the day and night.
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Affiliation(s)
- Wen-Dan Cheng
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou350002, China
| | - Chen-Sheng Lin
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou350002, China
| | - Hao Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou350002, China
| | - Guo-Liang Chai
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou350002, China
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11
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Wang C, Chen Y, Chen L. Four-dimensional orbital angular momentum Bell-state measurement assisted by the auxiliary polarization and path degrees of freedom. OPTICS EXPRESS 2022; 30:34468-34478. [PMID: 36242458 DOI: 10.1364/oe.469704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/22/2022] [Indexed: 06/16/2023]
Abstract
The orbital angular momentum (OAM) carried by twisted photons provides a promising playground for high-dimensional quantum information processing. While Bell-state measurement is the cornerstone for various quantum information applications, the deterministic discrimination of the complete high-dimensional Bell states with linear optics remains relatively unexplored in the OAM state space. Here, we demonstrate a theoretical scheme for the complete four-dimensional OAM Bell-state measurement by using the single-photon hyperentangled state analyzer, in which the auxiliary two-dimensional polarization entanglement and two-dimensional path entanglement are utilized. Our scheme offers an alternative route toward enhancing the channel capacity in quantum communication and increasing the robustness against deleterious noise in practical experiments with twisted photons.
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12
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Huang CX, Hu XM, Guo Y, Zhang C, Liu BH, Huang YF, Li CF, Guo GC, Gisin N, Branciard C, Tavakoli A. Entanglement Swapping and Quantum Correlations via Symmetric Joint Measurements. PHYSICAL REVIEW LETTERS 2022; 129:030502. [PMID: 35905332 DOI: 10.1103/physrevlett.129.030502] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
We use hyperentanglement to experimentally realize deterministic entanglement swapping based on quantum elegant joint measurements. These are joint projections of two qubits onto highly symmetric, isoentangled bases. We report measurement fidelities no smaller than 97.4%. We showcase the applications of these measurements by using the entanglement swapping procedure to demonstrate quantum correlations in the form of proof-of-principle violations of both bilocal Bell inequalities and more stringent correlation criteria corresponding to full network nonlocality. Our results are a foray into entangled measurements and nonlocality beyond the paradigmatic Bell state measurement and they show the relevance of more general measurements in entanglement swapping scenarios.
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Affiliation(s)
- Cen-Xiao Huang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Xiao-Min Hu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Yu Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Chao Zhang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Bi-Heng Liu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Yun-Feng Huang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Chuan-Feng Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Nicolas Gisin
- Group of Applied Physics, University of Geneva, 1211 Geneva 4, Switzerland
- Schaffhausen Institute of Technology-SIT, 1211 Geneva, Switzerland
| | - Cyril Branciard
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - Armin Tavakoli
- Institute for Quantum Optics and Quantum Information-IQOQI Vienna, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Vienna, Austria
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13
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Yan H, Zhong Y, Chang HS, Bienfait A, Chou MH, Conner CR, Dumur É, Grebel J, Povey RG, Cleland AN. Entanglement Purification and Protection in a Superconducting Quantum Network. PHYSICAL REVIEW LETTERS 2022; 128:080504. [PMID: 35275688 DOI: 10.1103/physrevlett.128.080504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
High-fidelity quantum entanglement is a key resource for quantum communication and distributed quantum computing, enabling quantum state teleportation, dense coding, and quantum encryption. Any sources of decoherence in the communication channel, however, degrade entanglement fidelity, thereby increasing the error rates of entangled state protocols. Entanglement purification provides a method to alleviate these nonidealities by distilling impure states into higher-fidelity entangled states. Here we demonstrate the entanglement purification of Bell pairs shared between two remote superconducting quantum nodes connected by a moderately lossy, 1-meter long superconducting communication cable. We use a purification process to correct the dominant amplitude damping errors caused by transmission through the cable, with fractional increases in fidelity as large as 25%, achieved for higher damping errors. The best final fidelity the purification achieves is 94.09±0.98%. In addition, we use both dynamical decoupling and Rabi driving to protect the entangled states from local noise, increasing the effective qubit dephasing time by a factor of 4, from 3 to 12 μs. These methods demonstrate the potential for the generation and preservation of very high-fidelity entanglement in a superconducting quantum communication network.
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Affiliation(s)
- Haoxiong Yan
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Youpeng Zhong
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Hung-Shen Chang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Audrey Bienfait
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Ming-Han Chou
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Christopher R Conner
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Étienne Dumur
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- Center for Molecular Engineering and Material Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Joel Grebel
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Rhys G Povey
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Andrew N Cleland
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- Center for Molecular Engineering and Material Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
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14
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Huang CX, Hu XM, Liu BH, Zhou L, Sheng YB, Li CF, Guo GC. Experimental one-step deterministic polarization entanglement purification. Sci Bull (Beijing) 2021; 67:593-597. [DOI: 10.1016/j.scib.2021.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/24/2021] [Accepted: 12/09/2021] [Indexed: 10/19/2022]
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15
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Sheng YB, Zhou L, Long GL. One-step quantum secure direct communication. Sci Bull (Beijing) 2021; 67:367-374. [DOI: 10.1016/j.scib.2021.11.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/13/2021] [Accepted: 10/26/2021] [Indexed: 10/19/2022]
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16
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Frequency and polarization emission properties of a photon-pair source based on a photonic crystal fiber. Sci Rep 2021; 11:18092. [PMID: 34508119 PMCID: PMC8433350 DOI: 10.1038/s41598-021-97563-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/23/2021] [Indexed: 11/12/2022] Open
Abstract
In this work, we experimentally demonstrate a photon-pair source with correlations in the frequency and polarization degrees of freedom. We base our source on the spontaneous four-wave mixing (SFWM) process in a photonic crystal fiber. We show theoretically that the two-photon state is the coherent superposition of up to six distinct SFWM processes, each corresponding to a distinct combination of polarizations for the four waves involved and giving rise to an energy-conserving pair of peaks. Our experimental measurements, both in terms of single and coincidence counts, confirm the presence of these pairs of peaks, while we also present related numerical simulations with excellent experiment-theory agreement. We explicitly show how the pump frequency and polarization may be used to effectively control the signal-idler photon-pair properties, defining which of the six processes can participate in the overall two-photon state and at which optical frequencies. We analyze the signal-idler correlations in frequency and polarization, and in terms of fiber characterization, we input the SFWM-peak experimental data into a genetic algorithm which successfully predicts the values of the parameters that characterize the fiber cross section, as well as predict the particular SFWM process associated with a given pair of peaks. We believe our work will help advance the exploitation of photon-pair correlations in the frequency and polarization degrees of freedom.
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Ecker S, Sohr P, Bulla L, Huber M, Bohmann M, Ursin R. Experimental Single-Copy Entanglement Distillation. PHYSICAL REVIEW LETTERS 2021; 127:040506. [PMID: 34355974 DOI: 10.1103/physrevlett.127.040506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
The phenomenon of entanglement marks one of the furthest departures from classical physics and is indispensable for quantum information processing. Despite its fundamental importance, the distribution of entanglement over long distances through photons is unfortunately hindered by unavoidable decoherence effects. Entanglement distillation is a means of restoring the quality of such diluted entanglement by concentrating it into a pair of qubits. Conventionally, this would be done by distributing multiple photon pairs and distilling the entanglement into a single pair. Here, we turn around this paradigm by utilizing pairs of single photons entangled in multiple degrees of freedom. Specifically, we make use of the polarization and the energy-time domain of photons, both of which are extensively field tested. We experimentally chart the domain of distillable states and achieve relative fidelity gains up to 13.8%. Compared to the two-copy scheme, the distillation rate of our single-copy scheme is several orders of magnitude higher, paving the way towards high-capacity and noise-resilient quantum networks.
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Affiliation(s)
- Sebastian Ecker
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Philipp Sohr
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Lukas Bulla
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Marcus Huber
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Institute for Atomic and Subatomic Physics, Vienna University of Technology, 1020 Vienna, Austria
| | - Martin Bohmann
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Rupert Ursin
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
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18
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Riera-Sàbat F, Sekatski P, Pirker A, Dür W. Entanglement-Assisted Entanglement Purification. PHYSICAL REVIEW LETTERS 2021; 127:040502. [PMID: 34355942 DOI: 10.1103/physrevlett.127.040502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
The efficient generation of high-fidelity entangled states is the key element for long-distance quantum communication, quantum computation, and other quantum technologies, and at the same time the most resource-consuming part in many schemes. We present a class of entanglement-assisted entanglement purification protocols that can generate high-fidelity entanglement from noisy, finite-size ensembles with improved yield and fidelity as compared to previous approaches. The scheme utilizes high-dimensional auxiliary entanglement to perform entangling nonlocal measurements and determine the number and positions of errors in an ensemble in a controlled and efficient way, without disturbing the entanglement of good pairs. Our protocols can deal with arbitrary errors, but are best suited for few errors, and work particularly well for decay noise. Our methods are applicable to moderately sized ensembles, as will be important for near term quantum devices.
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Affiliation(s)
- F Riera-Sàbat
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21a, 6020 Innsbruck, Austria
| | - P Sekatski
- Departement Physik, Universität Basel, Klingelbergstraße 82, 4056 Basel, Switzerland
| | - A Pirker
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21a, 6020 Innsbruck, Austria
| | - W Dür
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21a, 6020 Innsbruck, Austria
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Motazedifard A, Madani S, Dashkasan J, Vayaghan N. Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source. Heliyon 2021; 7:e07384. [PMID: 34258455 PMCID: PMC8255184 DOI: 10.1016/j.heliyon.2021.e07384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 06/05/2021] [Accepted: 06/21/2021] [Indexed: 12/05/2022] Open
Abstract
We have experimentally created a robust, ultrabright and phase-stable polarization-entangled state close to maximally entangled Bell-state with %98-fidelity using the type-II spontaneous parametric down-conversion (SPDC) process in periodically-poled KTiOPO4 (PPKTP) collinear crystal inside a Sagnac interferometer (SI). Bell inequality measurement, Freedman's test, as the different versions of CHSH inequality, and also visibility test which all can be seen as the nonlocal realism tests, imply that our created entangled state shows a strong violation from the classical physics or any hidden-variable theory. We have obtained very reliable and very strong Bell violation as S = 2.78 ± 0.01 with high brightnessV HV = % ( 99.969 ± 0.003 ) andV DA = % ( 96.751 ± 0.002 ) and very strong violation due to Freedman test asδ F = 0.01715 ± 0.00001 . Furthermore, using the tomographic reconstruction of quantum states together a maximum-likelihood-technique (MLT) as the numerical optimization, we obtain the physical non-negative definite density operator which shows the nonseparability and entanglement of our prepared state. By having the maximum likelihood density operator, we calculate some important entanglement-measures and entanglement entropies. The Sagnac configuration provides bidirectional crystal pumping yields to high-rate entanglement source which is very applicable in quantum communication, sensing and metrology as well as quantum information protocols, and has potential to be used in quantum illumination-based LIDAR and free-space quantum key distribution (QKD).
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Affiliation(s)
- Ali Motazedifard
- Quantum Optics Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
- Quantum Communication Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
- Quantum Sensing and Metrology Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
| | - S.A. Madani
- Quantum Optics Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
- Quantum Communication Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
| | - J.J. Dashkasan
- Quantum Optics Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
| | - N.S. Vayaghan
- Quantum Optics Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
- Quantum Communication Group, Iranian Center for Quantum Technologies (ICQTs), Tehran, Iran
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Heo J, Choi SG. Procedure via cross-Kerr nonlinearities for encoding single logical qubit information onto four-photon decoherence-free states. Sci Rep 2021; 11:10423. [PMID: 34001956 PMCID: PMC8129554 DOI: 10.1038/s41598-021-89809-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 04/30/2021] [Indexed: 02/03/2023] Open
Abstract
We propose a photonic procedure using cross-Kerr nonlinearities (XKNLs) to encode single logical qubit information onto four-photon decoherence-free states. In quantum information processing, a decoherence-free subspace can secure quantum information against collective decoherence. Therefore, we design a procedure employing nonlinear optical gates, which are composed of XKNLs, quantum bus beams, and photon-number-resolving measurements with linear optical devices, to conserve quantum information by encoding quantum information onto four-photon decoherence-free states (single logical qubit information). Based on our analysis in quantifying the affection (photon loss and dephasing) of the decoherence effect, we demonstrate the experimental condition to acquire the reliable procedure of single logical qubit information having the robustness against the decoherence effect.
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Affiliation(s)
- Jino Heo
- Research Institute for Computer and Information Communication (RICIC), Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea
| | - Seong-Gon Choi
- Research Institute for Computer and Information Communication (RICIC), Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea.
- College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea.
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Ghosh S, Rivera N, Eisenstein G, Kaminer I. Creating heralded hyper-entangled photons using Rydberg atoms. LIGHT, SCIENCE & APPLICATIONS 2021; 10:100. [PMID: 33976109 PMCID: PMC8113235 DOI: 10.1038/s41377-021-00537-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 03/15/2021] [Accepted: 04/18/2021] [Indexed: 06/12/2023]
Abstract
Entangled photon pairs are a fundamental component for testing the foundations of quantum mechanics, and for modern quantum technologies such as teleportation and secured communication. Current state-of-the-art sources are based on nonlinear processes that are limited in their efficiency and wavelength tunability. This motivates the exploration of physical mechanisms for entangled photon generation, with a special interest in mechanisms that can be heralded, preferably at telecommunications wavelengths. Here we present a mechanism for the generation of heralded entangled photons from Rydberg atom cavity quantum electrodynamics (cavity QED). We propose a scheme to demonstrate the mechanism and quantify its expected performance. The heralding of the process enables non-destructive detection of the photon pairs. The entangled photons are produced by exciting a rubidium atom to a Rydberg state, from where the atom decays via two-photon emission (TPE). A Rydberg blockade helps to excite a single Rydberg excitation while the input light field is more efficiently collectively absorbed by all the atoms. The TPE rate is significantly enhanced by a designed photonic cavity, whose many resonances also translate into high-dimensional entanglement. The resulting high-dimensionally entangled photons are entangled in more than one degree of freedom: in all of their spectral components, in addition to the polarization-forming a hyper-entangled state, which is particularly interesting in high information capacity quantum communication. We characterize the photon comb states by analyzing the Hong-Ou-Mandel interference and propose proof-of-concept experiments.
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Affiliation(s)
- Sutapa Ghosh
- Andrew and Erna Viterby Department of Electrical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
| | - Nicholas Rivera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gadi Eisenstein
- Andrew and Erna Viterby Department of Electrical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Ido Kaminer
- Andrew and Erna Viterby Department of Electrical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
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22
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Yan PS, Zhou L, Zhong W, Sheng YB. Feasible measurement-based entanglement purification in linear optics. OPTICS EXPRESS 2021; 29:9363-9384. [PMID: 33820366 DOI: 10.1364/oe.420348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
Entanglement purification is used to distill high quality entangled states from several noisy low quality entangled states, and it plays a key role in quantum repeater. The measurement-based entanglement purification protocol (MB-EPP) does not require local two-qubit gates or single-particle measurements on the noisy pairs and may offer significant advantages compared with the gate-based EPPs. We present an alternative MB-EPP in linear optics. Subsequently, we provide a detailed analysis on the realization of this MB-EPP using spontaneous parametric down conversion (SPDC) sources. By delicately designing the optical circuits, the double-pair emission noise caused by SPDC sources can be eliminated automatically. Combined with suitable quantum memory and entanglement swapping, this MB-EPP may have application potential in the implementation of a practical measurement-based quantum repeater.
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