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Sephton B, Vallés A, Nape I, Cox MA, Steinlechner F, Konrad T, Torres JP, Roux FS, Forbes A. Quantum transport of high-dimensional spatial information with a nonlinear detector. Nat Commun 2023; 14:8243. [PMID: 38092724 PMCID: PMC10719278 DOI: 10.1038/s41467-023-43949-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 11/24/2023] [Indexed: 12/17/2023] Open
Abstract
Information exchange between two distant parties, where information is shared without physically transporting it, is a crucial resource in future quantum networks. Doing so with high-dimensional states offers the promise of higher information capacity and improved resilience to noise, but progress to date has been limited. Here we demonstrate how a nonlinear parametric process allows for arbitrary high-dimensional state projections in the spatial degree of freedom, where a strong coherent field enhances the probability of the process. This allows us to experimentally realise quantum transport of high-dimensional spatial information facilitated by a quantum channel with a single entangled pair and a nonlinear spatial mode detector. Using sum frequency generation we upconvert one of the photons from an entangled pair resulting in high-dimensional spatial information transported to the other. We realise a d = 15 quantum channel for arbitrary photonic spatial modes which we demonstrate by faithfully transferring information encoded into orbital angular momentum, Hermite-Gaussian and arbitrary spatial mode superpositions, without requiring knowledge of the state to be sent. Our demonstration merges the nascent fields of nonlinear control of structured light with quantum processes, offering a new approach to harnessing high-dimensional quantum states, and may be extended to other degrees of freedom too.
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Affiliation(s)
- Bereneice Sephton
- School of Physics, University of the Witwatersrand, Wits, South Africa
| | - Adam Vallés
- School of Physics, University of the Witwatersrand, Wits, South Africa.
- Molecular Chirality Research Center, Chiba University, Chiba, Japan.
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain.
| | - Isaac Nape
- School of Physics, University of the Witwatersrand, Wits, South Africa
| | - Mitchell A Cox
- School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa
| | - Fabian Steinlechner
- Fraunhofer Institute for Applied Optics and Precision Engineering, Jena, Germany
- Friedrich Schiller University Jena, Abbe Center of Photonics, Jena, Germany
| | - Thomas Konrad
- School of Chemistry and Physics, University of KwaZulu-Natal, Durban, South Africa
- National Institute of Theoretical and Computational Sciences (NITheCS), KwaZulu-Natal, South Africa
| | - Juan P Torres
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
- Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, Barcelona, Spain
| | - Filippus S Roux
- National Metrology Institute of South Africa, Pretoria, South Africa
| | - Andrew Forbes
- School of Physics, University of the Witwatersrand, Wits, South Africa.
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Li Y, Huang SY, Wang M, Tu C, Wang XL, Li Y, Wang HT. Two-Measurement Tomography of High-Dimensional Orbital Angular Momentum Entanglement. PHYSICAL REVIEW LETTERS 2023; 130:050805. [PMID: 36800454 DOI: 10.1103/physrevlett.130.050805] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/09/2023] [Indexed: 06/18/2023]
Abstract
High-dimensional (HD) entanglement enables an encoding of more bits than in the two-dimensional case and promises to increase communication capacity over quantum channels and to improve robustness to noise. In practice, however, one of the central challenges is to devise efficient methods to quantify the HD entanglement explicitly. Full quantum state tomography is a standard technology to obtain all the information about the quantum state, but it becomes impractical because the required measurements increase exponentially with the dimension in HD systems. Hence, it is highly anticipated that a new method will be found for characterizing the HD entanglement with as few measurements as possible and without introducing unwarranted assumptions. Here, we present and demonstrate a scan-free tomography method independent of dimension, which only requires two measurements for the characterization of two-photon HD orbital angular momentum (OAM) entanglement. Taking Laguerre-Gaussian modes of photons as an example, the density matrices of OAM entangled states are experimentally reconstructed with very high fidelity. Our method is also generalized to the mixed HD OAM entanglement. Our results provide realistic approaches for quantifying more complex OAM entanglement in many scientific and engineering fields such as multiphoton HD quantum systems and quantum process tomography.
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Affiliation(s)
- Yi Li
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
| | - Shuang-Yin Huang
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Min Wang
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
| | - Chenghou Tu
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
| | - Xi-Lin Wang
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yongnan Li
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
| | - Hui-Tian Wang
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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Blasiak P, Borsuk E, Markiewicz M. Arbitrary entanglement of three qubits via linear optics. Sci Rep 2022; 12:21596. [PMID: 36517501 PMCID: PMC9751125 DOI: 10.1038/s41598-022-22835-4] [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: 08/22/2022] [Accepted: 10/19/2022] [Indexed: 12/23/2022] Open
Abstract
We present a linear-optical scheme for generating an arbitrary state of three qubits. It requires only three independent particles in the input and post-selection of the coincidence type at the output. The success probability of the protocol is equal for any desired state. Furthermore, the optical design remains insensitive to particle statistics (bosons, fermions or anyons). This approach builds upon the no-touching paradigm, which demonstrates the utility of particle indistinguishability as a resource of entanglement for practical applications.
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Affiliation(s)
- Pawel Blasiak
- grid.254024.50000 0000 9006 1798Institute for Quantum Studies, Chapman University, Orange, CA 92866 USA ,grid.418860.30000 0001 0942 8941Institute of Nuclear Physics Polish Academy of Sciences, 31342 Kraków, Poland
| | - Ewa Borsuk
- grid.418860.30000 0001 0942 8941Institute of Nuclear Physics Polish Academy of Sciences, 31342 Kraków, Poland
| | - Marcin Markiewicz
- grid.8585.00000 0001 2370 4076International Centre for Theory of Quantum Technologies, University of Gdańsk, 80308 Gdańsk, Poland
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Ding X, Ma J, Tan L, Helmy AS, Kang D. Biphoton engineering using modal spatial overlap on-chip. OPTICS LETTERS 2022; 47:6097-6100. [PMID: 37219181 DOI: 10.1364/ol.471346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 10/28/2022] [Indexed: 05/24/2023]
Abstract
Photon pairs generated by spontaneous parametric downconversion are essential for optical quantum information processing, in which the quality of biphoton states is crucial for the performance. To engineer the biphoton wave function (BWF) on-chip, the pump envelope function and the phase matching function are commonly adjusted, while the modal field overlap has been considered as a constant in the frequency range of interest. In this work, by using modal coupling in a system of coupled waveguides, we explore the modal field overlap as a new degree of freedom for biphoton engineering. We provide design examples for on-chip generations of polarization entangled photons and heralded single photons. This strategy can be applied to waveguides of different materials and structures, offering new possibilities for photonic quantum state engineering.
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He C, Shen Y, Forbes A. Towards higher-dimensional structured light. LIGHT, SCIENCE & APPLICATIONS 2022; 11:205. [PMID: 35790711 PMCID: PMC9256673 DOI: 10.1038/s41377-022-00897-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 06/12/2022] [Accepted: 06/16/2022] [Indexed: 05/17/2023]
Abstract
Structured light refers to the arbitrarily tailoring of optical fields in all their degrees of freedom (DoFs), from spatial to temporal. Although orbital angular momentum (OAM) is perhaps the most topical example, and celebrating 30 years since its connection to the spatial structure of light, control over other DoFs is slowly gaining traction, promising access to higher-dimensional forms of structured light. Nevertheless, harnessing these new DoFs in quantum and classical states remains challenging, with the toolkit still in its infancy. In this perspective, we discuss methods, challenges, and opportunities for the creation, detection, and control of multiple DoFs for higher-dimensional structured light. We present a roadmap for future development trends, from fundamental research to applications, concentrating on the potential for larger-capacity, higher-security information processing and communication, and beyond.
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Affiliation(s)
- Chao He
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK.
| | - Yijie Shen
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK.
| | - Andrew Forbes
- School of Physics, University of the Witwatersrand, Private Bag 3, Johannesburg, 2050, South Africa.
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