1
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Baek C, Bae J, Park J, Moon HS. Quantum interference of multidimensional quantum states via space-division multiplexing of a long-coherent single photon from a warm 87Rb atomic ensemble. OPTICS EXPRESS 2022; 30:43534-43542. [PMID: 36523049 DOI: 10.1364/oe.471412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 10/30/2022] [Indexed: 06/17/2023]
Abstract
The high-dimensional encoding of single photons can offer various possibilities for enhancing quantum information processing. This work experimentally demonstrates the quantum interference of an engineered multidimensional quantum state through the space-division multiplexing of a heralded single-photon state with a spatial light modulator (SLM) and spatial-mode mixing of a single photon through a long multimode fiber (MMF). In our experiment, the heralded single photon generated from a warm 87Rb atomic ensemble was bright, robust, and long-coherent. The multidimensional spatial quantum state of the long-coherent single photon was transported through a 4-m-long MMF and arbitrarily controlled using the SLM. We observed the quantum interference of a single-photon multidimensional spatial quantum state with a visibility of >95%. These results may have potential applications in quantum information processing, for example, in photonic variational quantum eigensolve with high-dimensional single photons and realizing high information capacity per photon for quantum communication.
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2
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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: 11] [Impact Index Per Article: 3.7] [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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3
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Fritz RA, Colón YJ, Herrera F. Engineering entangled photon pairs with metal-organic frameworks. Chem Sci 2021; 12:3475-3482. [PMID: 34163620 PMCID: PMC8179500 DOI: 10.1039/d0sc05572g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 01/19/2021] [Indexed: 11/21/2022] Open
Abstract
The discovery and design of new materials with competitive optical frequency conversion efficiencies can accelerate the development of scalable photonic quantum technologies. Metal-organic framework (MOF) crystals without inversion symmetry have shown potential for these applications, given their nonlinear optical properties and the combinatorial number of possibilities for MOF self-assembly. In order to accelerate the discovery of MOF materials for quantum optical technologies, scalable computational assessment tools are needed. We develop a multi-scale methodology to study the wavefunction of entangled photon pairs generated by selected non-centrosymmetric MOF crystals via spontaneous parametric down-conversion (SPDC). Starting from an optimized crystal structure, we predict the shape of the G (2) intensity correlation function for coincidence detection of the entangled pairs, produced under conditions of collinear type-I phase matching. The effective nonlinearities and photon pair correlation times obtained are comparable to those available with inorganic crystal standards. Our work thus provides fundamental insights into the structure-property relationships for entangled photon generation with metal-organic frameworks, paving the way for the automated discovery of molecular materials for optical quantum technology.
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Affiliation(s)
- Rubén A Fritz
- Department of Physics, Universidad de Santiago de Chile Av. Ecuador 3493 Santiago Chile
| | - Yamil J Colón
- Department of Chemical and Biomolecular Engineering, University of Notre Dame IN USA
| | - Felipe Herrera
- Department of Physics, Universidad de Santiago de Chile Av. Ecuador 3493 Santiago Chile
- ANID - Millennium Science Initiative Program, Millennium Institute for Research in Optics Chile
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4
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Hutter L, Lima G, Walborn SP. Boosting Entanglement Generation in Down-Conversion with Incoherent Illumination. PHYSICAL REVIEW LETTERS 2020; 125:193602. [PMID: 33216610 DOI: 10.1103/physrevlett.125.193602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/01/2020] [Indexed: 06/11/2023]
Abstract
Entangled photons produced by spontaneous parametric down-conversion have been of paramount importance for our current understanding of quantum mechanics and advances in quantum information. In this process, the quantum correlations of the down-converted photons are governed by the optical properties of the pump beam illuminating the nonlinear crystal. Extensively, the pump beam has been modeled by either coherent beams or by the well-known Gaussian-Schell model, which leads to the natural conclusion that a high degree of optical coherence is required for the generation of highly entangled states. Here, we show that when a novel class of partially coherent Gaussian pump beams is considered, a distinct type of quantum state can be generated for which the amount of entanglement increases inversely with the degree of coherence of the pump beam. This leads to highly incoherent yet highly entangled multiphoton states, which should have interesting consequences for photonic quantum information science.
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Affiliation(s)
- Lucas Hutter
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
- Instituto de Física, Universidade Federal Fluminense, Niteroi, RJ 24210-346, Brazil
| | - G Lima
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- ANID-Millennium Science Initiative Program-Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - S P Walborn
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- ANID-Millennium Science Initiative Program-Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
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5
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Fernandes MF, Solís-Prosser MA, Neves L. Ptychographic reconstruction of pure quantum states. OPTICS LETTERS 2020; 45:6002-6005. [PMID: 33137054 DOI: 10.1364/ol.401832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/28/2020] [Indexed: 06/11/2023]
Abstract
The quantum analogue of ptychography, a powerful coherent diffractive imaging technique, is a simple method for reconstructing d-dimensional pure states. It relies on measuring partially overlapping parts of the input state in a single orthonormal basis and feeding the outcomes to an iterative phase retrieval algorithm for postprocessing. We provide a proof of concept demonstration of this method by determining pure states given by superpositions of d transverse spatial modes of an optical field. A set of n rank-r projectors, diagonal in the spatial mode basis, is used to generate n partially overlapping parts of the input, and each part is projectively measured in the Fourier transformed basis. For d up to 32, we successfully reconstructed hundreds of random states using n=5 and n=d rank-⌈d/2⌉ projectors. The extension of quantum ptychography for other types of photonic spatial modes is outlined.
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6
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Fractional topological phase measurement with a hyperentangled photon source. Sci Rep 2019; 9:577. [PMID: 30679702 PMCID: PMC6345898 DOI: 10.1038/s41598-018-37344-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 12/04/2018] [Indexed: 11/08/2022] Open
Abstract
Pairs of photons simultaneously entangled in their path and polarization degrees of freedom are used to measure the topological phase acquired by bipartite entangled states. Conditional phase local unitary operations having the polarization degree of freedom as the control variable are applied. Qudits of arbitrary dimensions are encoded on the photons transverse positions while polarization entanglement is used as an auxiliary resource for quantum interference measurements. With this scheme the fractional phases predicted for dimensions d = 2, 3 and 4 could be measured with visibilities for the interference curves beyond the limit allowed for classical sources, which is expected for a source of quantum correlated photons. The strategy of perform a quantum interferometry experiment with photons entangled in an auxiliary degree of freedom and apply unitary local operations conditioned to this auxiliary variable shows an increase to the signal to noise ratio, simplifies alignment and can be used in different applications. This offers an interesting perspective for the efficient implementation of phase gates in quantum computing with hyperentangled photon sources in polarization and path degrees of freedom. Furthermore, one can conjecture whether the measured phase can serve as a dimensionality identifier of the Hilbert space dimension for an unknown state preparation.
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7
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Varga JJM, Rebón L, Pears Stefano Q, Iemmi C. Characterizing d-dimensional quantum channels by means of quantum process tomography. OPTICS LETTERS 2018; 43:4398-4401. [PMID: 30211874 DOI: 10.1364/ol.43.004398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/19/2018] [Indexed: 06/08/2023]
Abstract
In this Letter, we propose a simple optical architecture based on phase-only programmable spatial light modulators, in order to characterize general processes on photonic spatial quantum systems in a d>2 Hilbert space. We demonstrate the full reconstruction of typical noises affecting quantum computing, such as amplitude shifts, phase shifts, and depolarizing channels in dimension d=5. We have also reconstructed simulated atmospheric turbulences affecting a free-space transmission of qudits in dimension d=4. In each case, quantum process tomography was performed in order to obtain the matrix χ that fully describes the corresponding quantum channel, E. Fidelities between the states are experimentally obtained after going through the channel, and the expected ones are above 97%.
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8
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Aguilar EA, Farkas M, Martínez D, Alvarado M, Cariñe J, Xavier GB, Barra JF, Cañas G, Pawłowski M, Lima G. Certifying an Irreducible 1024-Dimensional Photonic State Using Refined Dimension Witnesses. PHYSICAL REVIEW LETTERS 2018; 120:230503. [PMID: 29932702 DOI: 10.1103/physrevlett.120.230503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 03/23/2018] [Indexed: 06/08/2023]
Abstract
We report on a new class of dimension witnesses, based on quantum random access codes, which are a function of the recorded statistics and that have different bounds for all possible decompositions of a high-dimensional physical system. Thus, it certifies the dimension of the system and has the new distinct feature of identifying whether the high-dimensional system is decomposable in terms of lower dimensional subsystems. To demonstrate the practicability of this technique, we used it to experimentally certify the generation of an irreducible 1024-dimensional photonic quantum state. Therefore, certifying that the state is not multipartite or encoded using noncoupled different degrees of freedom of a single photon. Our protocol should find applications in a broad class of modern quantum information experiments addressing the generation of high-dimensional quantum systems, where quantum tomography may become intractable.
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Affiliation(s)
- Edgar A Aguilar
- Institute of Theoretical Physics and Astrophysics, National Quantum Information Centre, Faculty of Mathematics, Physics and Informatics, University of Gdansk, 80-952 Gdansk, Poland
| | - Máté Farkas
- Institute of Theoretical Physics and Astrophysics, National Quantum Information Centre, Faculty of Mathematics, Physics and Informatics, University of Gdansk, 80-952 Gdansk, Poland
| | - Daniel Martínez
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Matías Alvarado
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Jaime Cariñe
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Guilherme B Xavier
- Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción, 160-C Concepción, Chile
- Institutionen för Systemteknik, Linköpings Universitet, 581 83 Linköping, Sweden
| | - Johanna F Barra
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Gustavo Cañas
- Departamento de Física, Universidad del Bio-Bio, Avenida Collao 1202, Concepción, Chile
| | - Marcin Pawłowski
- Institute of Theoretical Physics and Astrophysics, National Quantum Information Centre, Faculty of Mathematics, Physics and Informatics, University of Gdansk, 80-952 Gdansk, Poland
| | - Gustavo Lima
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
- Millennium Institute for Research in Optics, Universidad de Concepción, 160-C Concepción, Chile
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9
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Gómez ES, Riquelme P, Solís-Prosser MA, González P, Ortega E, Xavier GB, Lima G. Tunable entanglement distillation of spatially correlated down-converted photons. OPTICS EXPRESS 2018; 26:13961-13972. [PMID: 29877441 DOI: 10.1364/oe.26.013961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
We report on a new technique for entanglement distillation of the bipartite continuous variable state of spatially correlated photons generated in the spontaneous parametric down-conversion process (SPDC), where tunable non-Gaussian operations are implemented and the post-processed entanglement is certified in real-time using a single-photon sensitive electron multiplying CCD (EMCCD) camera. The local operations are performed using non-Gaussian filters modulated into a programmable spatial light modulator and, by using the EMCCD camera for actively recording the probability distributions of the twin-photons, one has fine control of the Schmidt number of the distilled state. We show that even simple non-Gaussian filters can be finely tuned to a ∼67% net gain of the initial entanglement generated in the SPDC process.
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10
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Li W, Zhao S. Bell's inequality tests via correlated diffraction of high-dimensional position-entangled two-photon states. Sci Rep 2018; 8:4812. [PMID: 29556069 PMCID: PMC5859148 DOI: 10.1038/s41598-018-23310-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 03/08/2018] [Indexed: 11/12/2022] Open
Abstract
Bell inequality testing, a well-established method to demonstrate quantum non-locality between remote two-partite entangled systems, is playing an important role in the field of quantum information. The extension to high-dimensional entangled systems, using the so-called Bell-CGLMP inequality, points the way in measuring joint probabilities, the kernel block to construct high dimensional Bell inequalities. Here we show that in theory the joint probability of a two-partite system entangled in a Hilbert space can be measured by choosing a set of basis vectors in its dual space that are related by a Fourier transformation. We next propose an experimental scheme to generate a high-dimensional position-entangled two-photon state aided by a combination of a multiple-slit and a 4 f system, and describe a method to test Bell’s inequality using correlated diffraction. Finally, we discuss in detail consequences of such Bell-test violations and experimental requirements.
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Affiliation(s)
- Wei Li
- Nanjing University of Posts and Telecommunications, Institute of Signal Processing and Transmission, Nanjing, 210003, China. .,Sunwave Communications CO, Hangzhou, 310053, China.
| | - Shengmei Zhao
- Nanjing University of Posts and Telecommunications, Institute of Signal Processing and Transmission, Nanjing, 210003, China.,Nanjing University of Posts and Telecommunications, Key Lab Broadband Wireless Communication and Sensor, Network, Ministy of Education, Nanjing, 210003, China
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11
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Generation of path-polarization hyperentanglement using quasi-phase-matching in quasi-periodic nonlinear photonic crystal. Sci Rep 2017; 7:4954. [PMID: 28694509 PMCID: PMC5504080 DOI: 10.1038/s41598-017-05271-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 05/26/2017] [Indexed: 12/04/2022] Open
Abstract
A compact scheme for the generation of path-polarization entangled photon pairs is proposed by using a quasi-periodic nonlinear photonic crystal to simultaneously accomplish four spontaneous parametric down-conversion processes. Moreover, we report experimental scheme to measure the polarization entanglement and path entanglement separately and theoretically get numerical results that verify some predictions about the hyperentanglement. This method can be expanded for the generation of multi-partite and two-photon path-polarization hyperentanglement in a single quasi-periodic nonlinear photonic crystal structure. This compact quantum light source can be used as a significant ingredient in quantum information science.
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12
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Lee HJ, Choi SK, Park HS. Experimental Demonstration of Four-Dimensional Photonic Spatial Entanglement between Multi-core Optical Fibres. Sci Rep 2017; 7:4302. [PMID: 28655886 PMCID: PMC5487350 DOI: 10.1038/s41598-017-04444-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 05/16/2017] [Indexed: 11/26/2022] Open
Abstract
Fibre transport of multi-dimensional photonic quantum states promises high information capacity per photon without space restriction. This work experimentally demonstrates transmission of spatial ququarts through multi-core optical fibres and measurement of the entanglement between two fibres with quantum state analyzers, each composed of a spatial light modulator and a single-mode fibre. Quantum state tomography reconstructs the four-dimension entangled state that verifies the nonlocality through concurrences in two-dimensional subspaces, a lower bound of four-dimensional concurrence and a Bell-type CGLMP inequality.
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Affiliation(s)
- Hee Jung Lee
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea
| | - Sang-Kyung Choi
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea
| | - Hee Su Park
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea.
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13
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Solís-Prosser MA, Fernandes MF, Jiménez O, Delgado A, Neves L. Experimental Minimum-Error Quantum-State Discrimination in High Dimensions. PHYSICAL REVIEW LETTERS 2017; 118:100501. [PMID: 28339223 DOI: 10.1103/physrevlett.118.100501] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 05/25/2023]
Abstract
Quantum mechanics forbids perfect discrimination among nonorthogonal states through a single shot measurement. To optimize this task, many strategies were devised that later became fundamental tools for quantum information processing. Here, we address the pioneering minimum-error (ME) measurement and give the first experimental demonstration of its application for discriminating nonorthogonal states in high dimensions. Our scheme is designed to distinguish symmetric pure states encoded in the transverse spatial modes of an optical field; the optimal measurement is performed by a projection onto the Fourier transform basis of these modes. For dimensions ranging from D=2 to D=21 and nearly 14 000 states tested, the deviations of the experimental results from the theoretical values range from 0.3% to 3.6% (getting below 2% for the vast majority), thus showing the excellent performance of our scheme. This ME measurement is a building block for high-dimensional implementations of many quantum communication protocols, including probabilistic state discrimination, dense coding with nonmaximal entanglement, and cryptographic schemes.
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Affiliation(s)
- M A Solís-Prosser
- Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - M F Fernandes
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - O Jiménez
- Departamento de Física, Facultad de Ciencias Básicas, Universidad de Antofagasta, Casilla 170, Antofagasta, Chile
| | - A Delgado
- Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - L Neves
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
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14
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De Assis PL, Carvalho MAD, Berruezo LP, Ferraz J, Pádua S. Generation of two pairs of qudits using four photons and a single degree of freedom. OPTICS EXPRESS 2016; 24:30149-30163. [PMID: 28059292 DOI: 10.1364/oe.24.030149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Qudits, d-level quantum systems, have been shown to provide a better resource for quantum key distribution and other Quantum Information protocols. It is customary to generate photonic qudits using more than one degree of freedom of the same photon. In much the same way, multi-qubit states are generated using only a pair of photons and ingenious ways to manipulate more than one degree of freedom independently. In contrast to such costly implementations in terms of quantum resources, we present the controlled generation of two copies of two-qudit states using four photons and a single degree of freedom, transverse momentum. The degree of entanglement within each pair was inferred by exploiting the availability of two copies of the same state, without the need of a full tomographic reconstruction of the states, and both highly-entangled and separable states were generated. We show theoretically that the set of states obtainable using our setup is very diverse, ranging from maximally entangled states of qudits to separable states.
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15
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Unternährer M, Bessire B, Gasparini L, Stoppa D, Stefanov A. Coincidence detection of spatially correlated photon pairs with a monolithic time-resolving detector array. OPTICS EXPRESS 2016; 24:28829-28841. [PMID: 27958526 DOI: 10.1364/oe.24.028829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We demonstrate coincidence measurements of spatially entangled photons by means of a multi-pixel based detection array. The sensor, originally developed for positron emission tomography applications, is a fully digital 8×16 silicon photomultiplier array allowing not only photon counting but also per-pixel time stamping of the arrived photons with an effective resolution of 265 ps. Together with a frame rate of 500 kfps, this property exceeds the capabilities of conventional charge-coupled device cameras which have become of growing interest for the detection of transversely correlated photon pairs. The sensor is used to measure a second-order correlation function for various non-collinear configurations of entangled photons generated by spontaneous parametric down-conversion. The experimental results are compared to theory.
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16
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He LY, Wang TJ, Wang C. Construction of high-dimensional universal quantum logic gates using a Λ system coupled with a whispering-gallery-mode microresonator. OPTICS EXPRESS 2016; 24:15429-15445. [PMID: 27410818 DOI: 10.1364/oe.24.015429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
High-dimensional quantum system provides a higher capacity of quantum channel, which exhibits potential applications in quantum information processing. However, high-dimensional universal quantum logic gates is difficult to achieve directly with only high-dimensional interaction between two quantum systems and requires a large number of two-dimensional gates to build even a small high-dimensional quantum circuits. In this paper, we propose a scheme to implement a general controlled-flip (CF) gate where the high-dimensional single photon serve as the target qudit and stationary qubits work as the control logic qudit, by employing a three-level Λ-type system coupled with a whispering-gallery-mode microresonator. In our scheme, the required number of interaction times between the photon and solid state system reduce greatly compared with the traditional method which decomposes the high-dimensional Hilbert space into 2-dimensional quantum space, and it is on a shorter temporal scale for the experimental realization. Moreover, we discuss the performance and feasibility of our hybrid CF gate, concluding that it can be easily extended to a 2n-dimensional case and it is feasible with current technology.
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17
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Marques B, Matoso AA, Pimenta WM, Gutiérrez-Esparza AJ, Santos MF, Pádua S. Experimental simulation of decoherence in photonics qudits. Sci Rep 2015; 5:16049. [PMID: 26527330 PMCID: PMC4630612 DOI: 10.1038/srep16049] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 09/02/2015] [Indexed: 11/09/2022] Open
Abstract
We experimentally perform the simulation of open quantum dynamics in single-qudit systems. Using a spatial light modulator as a dissipative optical device, we implement dissipative-dynamical maps onto qudits encoded in the transverse momentum of spontaneous parametric down-converted photon pairs. We show a well-controlled technique to prepare entangled qudits states as well as to implement dissipative local measurements; the latter realize two specific dynamics: dephasing and amplitude damping. Our work represents a new analogy-dynamical experiment for simulating an open quantum system.
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Affiliation(s)
- B Marques
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG - Brazil.,Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - A A Matoso
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG - Brazil
| | - W M Pimenta
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG - Brazil
| | - A J Gutiérrez-Esparza
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG - Brazil
| | - M F Santos
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG - Brazil
| | - S Pádua
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG - Brazil
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18
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Goyeneche D, Cañas G, Etcheverry S, Gómez ES, Xavier GB, Lima G, Delgado A. Five Measurement Bases Determine Pure Quantum States on Any Dimension. PHYSICAL REVIEW LETTERS 2015; 115:090401. [PMID: 26371631 DOI: 10.1103/physrevlett.115.090401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Indexed: 06/05/2023]
Abstract
A long-standing problem in quantum mechanics is the minimum number of observables required for the characterization of unknown pure quantum states. The solution to this problem is especially important for the developing field of high-dimensional quantum information processing. In this work we demonstrate that any pure d-dimensional state is unambiguously reconstructed by measuring five observables, that is, via projective measurements onto the states of five orthonormal bases. Thus, in our method the total number of different measurement outcomes (5d) scales linearly with d. The state reconstruction is robust against experimental errors and requires simple postprocessing, regardless of d. We experimentally demonstrate the feasibility of our scheme through the reconstruction of eight-dimensional quantum states, encoded in the momentum of single photons.
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Affiliation(s)
- D Goyeneche
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - G Cañas
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - S Etcheverry
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - E S Gómez
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - G B Xavier
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Departamento de Ingeniería Eléctrica, Universidad de Concepción, 160-C Concepción, Chile
| | - G Lima
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - A Delgado
- Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile
- MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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Luo MX, Deng Y, Li HR, Ma SY. Photonic ququart logic assisted by the cavity-QED system. Sci Rep 2015; 5:13255. [PMID: 26272869 PMCID: PMC4536487 DOI: 10.1038/srep13255] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/23/2015] [Indexed: 11/23/2022] Open
Abstract
Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions of qubit systems, we investigate the possibility of ququart systems (four-dimensional states) dependent on two DOFs of photon systems. We propose some useful one-parameter four-dimensional quantum transformations for the construction of universal ququart logic gates. The interface between the spin of a photon and an electron spin confined in a quantum dot embedded in a microcavity is applied to build universal ququart logic gates on the photon system with two freedoms. Our elementary controlled-ququart gates cost no more than 8 CNOT gates in a qubit system, which is far less than the 104 CNOT gates required for a general four-qubit logic gate. The ququart logic is also used to generate useful hyperentanglements and hyperentanglement-assisted quantum error-correcting code, which may be available in modern physical technology.
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Affiliation(s)
- Ming-Xing Luo
- Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China
| | - Yun Deng
- School of Computer Science, Sichuan University of Science & Engineering, Zigong 64300, China
| | - Hui-Ran Li
- Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China
| | - Song-Ya Ma
- School of Mathematics and Statistics, Henan University, Kaifeng 475004, China
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20
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Cañas G, Arias M, Etcheverry S, Gómez ES, Cabello A, Xavier GB, Lima G. Applying the simplest Kochen-Specker set for quantum information processing. PHYSICAL REVIEW LETTERS 2014; 113:090404. [PMID: 25215966 DOI: 10.1103/physrevlett.113.090404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Indexed: 06/03/2023]
Abstract
Kochen-Specker (KS) sets are key tools for proving some fundamental results in quantum theory and also have potential applications in quantum information processing. However, so far, their intrinsic complexity has prevented experimentalists from using them for any application. The KS set requiring the smallest number of contexts has been recently found. Relying on this simple KS set, here we report an input state-independent experimental technique to certify whether a set of measurements is actually accessing a preestablished quantum six-dimensional space encoded in the transverse momentum of single photons.
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Affiliation(s)
- Gustavo Cañas
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile and Center for Optics and Photonics, Universidad de Concepción, 160-C Concepción, Chile and MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Mauricio Arias
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile and Center for Optics and Photonics, Universidad de Concepción, 160-C Concepción, Chile and MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Sebastián Etcheverry
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile and Center for Optics and Photonics, Universidad de Concepción, 160-C Concepción, Chile and MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Esteban S Gómez
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile and Center for Optics and Photonics, Universidad de Concepción, 160-C Concepción, Chile and MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
| | - Adán Cabello
- Departamento de Física Aplicada II, Universidad de Sevilla, E-41012, Sevilla, Spain
| | - Guilherme B Xavier
- Center for Optics and Photonics, Universidad de Concepción, 160-C Concepción, Chile and MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile and Departamento de Ingeniería Eléctrica, Universidad de Concepción, 160-C Concepción, Chile
| | - Gustavo Lima
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile and Center for Optics and Photonics, Universidad de Concepción, 160-C Concepción, Chile and MSI-Nucleus for Advanced Optics, Universidad de Concepción, 160-C Concepción, Chile
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21
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Paul EC, Hor-Meyll M, Ribeiro PHS, Walborn SP. Measuring spatial correlations of photon pairs by automated raster scanning with spatial light modulators. Sci Rep 2014; 4:5337. [PMID: 24939691 PMCID: PMC4061558 DOI: 10.1038/srep05337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/22/2014] [Indexed: 11/09/2022] Open
Abstract
We demonstrate the use of a phase-only spatial light modulator for the measurement of transverse spatial distributions of coincidence counts between twin photon beams, in a fully automated fashion. This is accomplished by means of the polarization dependence of the modulator, which allows the conversion of a phase pattern into an amplitude pattern. We also present a correction procedure, that accounts for unwanted coincidence counts due to polarization decoherence effects.
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Affiliation(s)
- E C Paul
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
| | - M Hor-Meyll
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
| | - P H Souto Ribeiro
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
| | - S P Walborn
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
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22
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Etcheverry S, Cañas G, Gómez ES, Nogueira WAT, Saavedra C, Xavier GB, Lima G. Quantum key distribution session with 16-dimensional photonic states. Sci Rep 2014; 3:2316. [PMID: 23897033 PMCID: PMC3727059 DOI: 10.1038/srep02316] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 07/15/2013] [Indexed: 11/25/2022] Open
Abstract
The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.
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Affiliation(s)
- S Etcheverry
- Departamento de Física, Universidad de Concepción, 160-C Concepción, Chile
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23
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Luo MX, Chen XB, Yang YX, Wang X. Geometry of quantum computation with qudits. Sci Rep 2014; 4:4044. [PMID: 24509710 PMCID: PMC4070285 DOI: 10.1038/srep04044] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 01/24/2014] [Indexed: 11/09/2022] Open
Abstract
The circuit complexity of quantum qubit system evolution as a primitive problem in quantum computation has been discussed widely. We investigate this problem in terms of qudit system. Using the Riemannian geometry the optimal quantum circuits are equivalent to the geodetic evolutions in specially curved parametrization of SU(dn). And the quantum circuit complexity is explicitly dependent of controllable approximation error bound.
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Affiliation(s)
- Ming-Xing Luo
- 1] Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China [2] State key Laboratory of Networking and Switching Technology (Beijing University of Posts and Telecommunications), Beijing 100876, China [3] State Key Laboratory of Information Security (Graduate University of Chinese Academy of Sciences), Beijing 100049, China
| | - Xiu-Bo Chen
- State key Laboratory of Networking and Switching Technology (Beijing University of Posts and Telecommunications), Beijing 100876, China
| | - Yi-Xian Yang
- State key Laboratory of Networking and Switching Technology (Beijing University of Posts and Telecommunications), Beijing 100876, China
| | - Xiaojun Wang
- School of Electronic Engineering, Dublin City University, Dublin 9, Ireland
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24
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Solís-Prosser MA, Arias A, Varga JJM, Rebón L, Ledesma S, Iemmi C, Neves L. Preparing arbitrary pure states of spatial qudits with a single phase-only spatial light modulator. OPTICS LETTERS 2013; 38:4762-4765. [PMID: 24322126 DOI: 10.1364/ol.38.004762] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Spatial qudits are D-dimensional (D ≥ 2) quantum systems carrying information encoded in the discretized transverse momentum and position of single photons. We present a proof-of-principle demonstration of a method for preparing arbitrary pure states of such systems by using a single phase-only spatial light modulator (SLM). The method relies on the encoding of the complex transmission function corresponding to a given spatial qudit state onto a preset diffraction order of a phase-only grating function addressed at the SLM. Fidelities of preparation above 94% were obtained with this method, which is simpler, less costly, and more efficient than those that require two SLMs for the same purpose.
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25
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Gómez ES, Nogueira WAT, Monken CH, Lima G. Quantifying the non-Gaussianity of the state of spatially correlated down-converted photons. OPTICS EXPRESS 2012; 20:3753-3772. [PMID: 22418133 DOI: 10.1364/oe.20.003753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The state of spatially correlated down-converted photons is usually treated as a two-mode Gaussian entangled state. While intuitively this seems to be reasonable, it is known that new structures in the spatial distributions of these photons can be observed when the phase-matching conditions are properly taken into account. Here, we study how the variances of the near- and far-field conditional probabilities are affected by the phase-matching functions, and we analyze the role of the EPR-criterion regarding the non-Gaussianity and entanglement detection of the spatial two-photon state of spontaneous parametric down-conversion (SPDC). Then we introduce a statistical measure, based on the negentropy of the joint distributions at the near- and far-field planes, which allows for the quantification of the non-Gaussianity of this state. This measure of non-Gaussianity requires only the measurement of the diagonal covariance sub-matrices, and will be relevant for new applications of the spatial correlation of SPDC in CV quantum information processing.
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Affiliation(s)
- E S Gómez
- Departamento de Física, Universidad de Concepcíon, 160-C Concepcíon, Chile
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26
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Brainis E. Quantum imaging with N-photon states in position space. OPTICS EXPRESS 2011; 19:24228-24240. [PMID: 22109449 DOI: 10.1364/oe.19.024228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigate the physics of quantum imaging with N > 2 entangled photons in position space. It is shown that, in paraxial approximation, the space-time propagation of the quantum state can be described by a generalized Huygens-Fresnel principle for the N-photon wave function. The formalism allows the initial conditions to be set on multiple reference planes, which is very convenient to describe the generation of multiple photon pairs in separate thin crystals. Applications involving state shaping and spatial entanglement swapping are developed.
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Affiliation(s)
- E Brainis
- Service OPERA, Universit´e libre de Bruxelles, Avenue F. D. Roosevelt 50, B-1050 Bruxelles, Belgium.
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27
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On-chip steering of entangled photons in nonlinear photonic crystals. Nat Commun 2011; 2:429. [PMID: 21847103 DOI: 10.1038/ncomms1439] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 07/18/2011] [Indexed: 11/08/2022] Open
Abstract
One promising technique for working toward practical photonic quantum technologies is to implement multiple operations on a monolithic chip, thereby improving stability, scalability and miniaturization. The on-chip spatial control of entangled photons will certainly benefit numerous applications, including quantum imaging, quantum lithography, quantum metrology and quantum computation. However, external optical elements are usually required to spatially control the entangled photons. Here we present the first experimental demonstration of on-chip spatial control of entangled photons, based on a domain-engineered nonlinear photonic crystal. We manipulate the entangled photons using the inherent properties of the crystal during the parametric downconversion, demonstrating two-photon focusing and beam-splitting from a periodically poled lithium tantalate crystal with a parabolic phase profile. These experimental results indicate that versatile and precise spatial control of entangled photons is achievable. Because they may be operated independent of any bulk optical elements, domain-engineered nonlinear photonic crystals may prove to be a valuable ingredient in on-chip integrated quantum optics.
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28
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Lima G, Neves L, Guzmán R, Gómez ES, Nogueira WAT, Delgado A, Vargas A, Saavedra C. Experimental quantum tomography of photonic qudits via mutually unbiased basis. OPTICS EXPRESS 2011; 19:3542-3552. [PMID: 21369178 DOI: 10.1364/oe.19.003542] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present the experimental quantum tomography of 7- and 8-dimensional quantum systems based on projective measurements in the mutually unbiased basis (MUB-QT). One of the advantages of MUB-QT is that it requires projections from a minimal number of bases to be performed. In our scheme, the higher dimensional quantum systems are encoded using the propagation modes of single photons, and we take advantage of the capabilities of amplitude- and phase-modulation of programmable spatial light modulators to implement the MUB-QT.
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Affiliation(s)
- G Lima
- Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción, Chile.
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29
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de Assis PL, Carvalho MAD, Berruezo LP, Ferraz J, Santos IF, Sciarrino F, Pádua S. Control of quantum transverse correlations on a four-photon system. OPTICS EXPRESS 2011; 19:3715-3729. [PMID: 21369197 DOI: 10.1364/oe.19.003715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Control of spatial quantum correlations in bi-photons is one of the fundamental principles of Quantum Imaging. Up to now, experiments have been restricted to controlling the state of a single bi-photon, by using linear optical elements. In this work we demonstrate experimental control of quantum correlations in a four-photon state comprised of two pairs of photons. Our scheme is based on a high-efficiency parametric downconversion source coupled to a double slit by a variable linear optical setup, in order to obtain spatially encoded qubits. Both entangled and separable pairs have been obtained, by altering experimental parameters. We show how the correlations influence both the interference and diffraction on the double slit.
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Affiliation(s)
- P-L de Assis
- Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-980, Belo Horizonte, Brazil.
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30
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Pimenta WM, Marques B, Carvalho MAD, Barros MR, Fonseca JG, Ferraz J, Cunha MT, Pádua S. Minimal state tomography of spatial qubits using a spatial light modulator. OPTICS EXPRESS 2010; 18:24423-24433. [PMID: 21164789 DOI: 10.1364/oe.18.024423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report minimal quantum state tomography with spatial qubits created by a pair of parametric down converted twin-photons passing through a double-slit. A novel experimental setup is used, which includes a Spatial Light Modulator, as a fundamental tool, to reconstruct the state density matrix. The theory needed to perform a minimal quantum tomography is described. The density matrix is experimentally obtained for the two-qubit photonic states in spatial variables.
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Affiliation(s)
- W M Pimenta
- Departamento de Física, Universidade Federal de Minas Gerais, caixa postal 702, 30123-970, Belo Horizonte, MG-Brazil
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31
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Jha AK, Leach J, Jack B, Franke-Arnold S, Barnett SM, Boyd RW, Padgett MJ. Angular two-photon interference and angular two-qubit states. PHYSICAL REVIEW LETTERS 2010; 104:010501. [PMID: 20366353 DOI: 10.1103/physrevlett.104.010501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Indexed: 05/29/2023]
Abstract
Using angular-position-orbital-angular-momentum entangled photons, we study angular two-photon interference in a scheme in which entangled photons are made to pass through apertures in the form of double angular slits, and using this scheme, we demonstrate an entangled two-qubit state that is based on the angular-position correlations of entangled photons. The entanglement of the two-qubit state is quantified in terms of concurrence. These results provide an additional means for preparing entangled quantum states for use in quantum information protocols.
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Affiliation(s)
- Anand Kumar Jha
- Institute of Optics, University of Rochester, Rochester, New York 14627, USA
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32
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Gomes RM, Salles A, Toscano F, Ribeiro PHS, Walborn SP. Observation of a nonlocal optical vortex. PHYSICAL REVIEW LETTERS 2009; 103:033602. [PMID: 19659278 DOI: 10.1103/physrevlett.103.033602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Indexed: 05/28/2023]
Abstract
We report the observation of an optical vortex in the correlations of photons produced from spontaneous parametric down-conversion. The singularity appears in a nonlocal coordinate plane consisting of 1 degree of freedom of each photon.
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Affiliation(s)
- R M Gomes
- Instituto de Física, Universidade Federal de Goiás, GO 74.001-970, Brazil
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33
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Lima G, Vargas A, Neves L, Guzmán R, Saavedra C. Manipulating spatial qudit states with programmable optical devices. OPTICS EXPRESS 2009; 17:10688-10696. [PMID: 19550465 DOI: 10.1364/oe.17.010688] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The study of how to generate high-dimensional quantum states (qudits) is justified by the advantages that they can bring for the field of quantum information. However, to have some real practical potential for quantum communication, these states must be also of simple manipulation. Spatial qudits states, which are generated by engineering the transverse momentum of the parametric down-converted photons, have been until now considered of hard manipulation. Nevertheless, we show in this work a simple technique for modifying these states. This technique is based on the use of programmable diffractive optical devices, that can act as spatial light modulators, to define the Hilbert space of these photons instead of pre-fabricated multi-slits.
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Affiliation(s)
- G Lima
- Center for Quantum Optics and Quantum Information, Departamento de Física, Universidad de Concepción, Concepción, Chile.
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34
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35
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Beenakker CWJ, Venderbos JWF, van Exter MP. Two-photon speckle as a probe of multi-dimensional entanglement. PHYSICAL REVIEW LETTERS 2009; 102:193601. [PMID: 19518950 DOI: 10.1103/physrevlett.102.193601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Indexed: 05/27/2023]
Abstract
We calculate the statistical distribution P2(I2) of the speckle pattern produced by a photon pair current I2 transmitted through a random medium, and compare it with the single-photon speckle distribution P1(I1). We show that the purity of a two-photon density matrix can be directly extracted from the first two moments of P1 and P2. A one-to-one relationship is derived between P1 and P2 if the photon pair is in an M-dimensional entangled pure state. For M>>1 the single-photon speckle disappears, while the two-photon speckle acquires an exponential distribution.
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Affiliation(s)
- C W J Beenakker
- Instituut-Lorentz, Leiden University, P.O. Box 9506, 2300 RA Leiden, The Netherlands
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36
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Rossi A, Vallone G, Chiuri A, De Martini F, Mataloni P. Multipath entanglement of two photons. PHYSICAL REVIEW LETTERS 2009; 102:153902. [PMID: 19518632 DOI: 10.1103/physrevlett.102.153902] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Indexed: 05/27/2023]
Abstract
We present a novel optical device based on an integrated system of microlenses and single-mode optical fibers. It allows us to collect and direct into many modes two photons generated by spontaneous parametric down-conversion. By this device multiqubit entangled states and/or multilevel qudit states of two photons, encoded in the longitudinal momentum degree of freedom, are created. The multipath photon entanglement realized by this device is expected to find important applications in modern quantum information technology.
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Affiliation(s)
- Alessandro Rossi
- Dipartimento di Fisica, Sapienza Università di Roma, Roma 00185, Italy
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37
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Yu XQ, Xu P, Xie ZD, Wang JF, Leng HY, Zhao JS, Zhu SN, Ming NB. Transforming spatial entanglement using a domain-engineering technique. PHYSICAL REVIEW LETTERS 2008; 101:233601. [PMID: 19113550 DOI: 10.1103/physrevlett.101.233601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Indexed: 05/27/2023]
Abstract
We study the spatial correlation of a two-photon entangled state produced in a multistripe periodically poled LiTaO3 crystal by spontaneous parametric down-conversion. The far-field diffraction-interference experiments reveal that the transverse modulation of domain patterns transforms the spatial mode function of the two-photon state. This result offers an approach to prepare a novel type of two-photon state with a unique spatial entanglement by using a domain-engineering technique.
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Affiliation(s)
- X Q Yu
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, China
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38
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Pors JB, Oemrawsingh SSR, Aiello A, van Exter MP, Eliel ER, 't Hooft GW, Woerdman JP. Shannon dimensionality of quantum channels and its application to photon entanglement. PHYSICAL REVIEW LETTERS 2008; 101:120502. [PMID: 18851350 DOI: 10.1103/physrevlett.101.120502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Indexed: 05/14/2023]
Abstract
We introduce the concept of Shannon dimensionality D as a new way to quantify bipartite entanglement as measured in an experiment. This is applied to orbital-angular-momentum entanglement of two photons, using two state analyzers composed of a rotatable angular-sector phase plate that is lens coupled to a single-mode fiber. We can deduce the value of D directly from the observed two-photon coincidence fringe. In our experiment, D varies between 2 and 6, depending on the experimental conditions. We predict how the Shannon dimensionality evolves when the number of angular sectors imprinted in the phase plate is increased and anticipate that D approximately 50 is experimentally within reach.
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Affiliation(s)
- J B Pors
- Huygens Laboratory, Leiden University, Leiden, The Netherlands.
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39
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Zhang L, Silberhorn C, Walmsley IA. Secure quantum key distribution using continuous variables of single photons. PHYSICAL REVIEW LETTERS 2008; 100:110504. [PMID: 18517770 DOI: 10.1103/physrevlett.100.110504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Indexed: 05/26/2023]
Abstract
We analyze the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons from a realistic source, and show that the standard measures of security known for quadrature-based continuous variable quantum cryptography (CV-QKD) are inadequate. A specific simple eavesdropping attack is analyzed to illuminate how secret information may be distilled well beyond the bounds of the usual CV-QKD measures.
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Affiliation(s)
- Lijian Zhang
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
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40
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Yarnall T, Abouraddy AF, Saleh BEA, Teich MC. Synthesis and analysis of entangled photonic qubits in spatial-parity space. PHYSICAL REVIEW LETTERS 2007; 99:250502. [PMID: 18233506 DOI: 10.1103/physrevlett.99.250502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2007] [Revised: 06/26/2007] [Indexed: 05/25/2023]
Abstract
We present the novel embodiment of a photonic qubit that makes use of one continuous spatial degree of freedom of a single photon and relies on the parity of the photon's transverse spatial distribution. Using optical spontaneous parametric down-conversion to produce photon pairs, we demonstrate the controlled generation of entangled-photon states in this new space. Specifically, two Bell states, and a continuum of their superpositions, are generated by simple manipulation of a classical parameter, the optical-pump spatial parity, and not by manipulation of the entangled photons themselves. An interferometric device, isomorphic in action to a polarizing beam splitter, projects the spatial-parity states onto an even-odd basis. This new physical realization of photonic qubits could be used as a foundation for future experiments in quantum information processing.
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Affiliation(s)
- Timothy Yarnall
- Quantum Imaging Laboratory, Departments of Electrical & Computer Engineering and Physics, Boston University, Boston, Massachusetts 02215-2421, USA
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41
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Ali-Khan I, Broadbent CJ, Howell JC. Large-alphabet quantum key distribution using energy-time entangled bipartite States. PHYSICAL REVIEW LETTERS 2007; 98:060503. [PMID: 17358925 DOI: 10.1103/physrevlett.98.060503] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 11/27/2006] [Indexed: 05/14/2023]
Abstract
We present a protocol for large-alphabet quantum key distribution (QKD) using energy-time entangled biphotons. Binned, high-resolution timing measurements are used to generate a large-alphabet key with over 10 bits of information per photon pair, albeit with large noise. QKD with 5% bit error rate is demonstrated with 4 bits of information per photon pair, where the security of the quantum channel is determined by the visibility of Franson interference fringes. The protocol is easily generalizable to even larger alphabets, and utilizes energy-time entanglement which is robust to transmission over large distances in fiber.
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Affiliation(s)
- Irfan Ali-Khan
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
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42
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Moreva EV, Maslennikov GA, Straupe SS, Kulik SP. Realization of four-level qudits using biphotons. PHYSICAL REVIEW LETTERS 2006; 97:023602. [PMID: 16907441 DOI: 10.1103/physrevlett.97.023602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Indexed: 05/11/2023]
Abstract
The novel experimental realization of four-level optical quantum systems (ququarts) is presented. We exploit the polarization properties of the frequency nondegenerate biphoton field to obtain such systems. A simple method that does not rely on am interferometer is used to generate and measure the sequence of states that can be used in quantum key distribution protocol.
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Affiliation(s)
- E V Moreva
- Moscow Engineering Physics Institute, State University, Russia.
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43
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Walborn SP, Lemelle DS, Almeida MP, Ribeiro PHS. Quantum key distribution with higher-order alphabets using spatially encoded qudits. PHYSICAL REVIEW LETTERS 2006; 96:090501. [PMID: 16606248 DOI: 10.1103/physrevlett.96.090501] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Indexed: 05/08/2023]
Abstract
We present a proof of principle demonstration of a quantum key distribution scheme in higher-order -dimensional alphabets using spatial degrees of freedom of photons. Our implementation allows for the transmission of 4.56 bits per sifted photon, while providing improved security: an intercept-resend attack on all photons would induce an average error rate of 0.47. Using our system, it should be possible to send more than a byte of information per sifted photon.
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Affiliation(s)
- S P Walborn
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil.
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