1
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McCaw A, Ewaniuk J, Shastri BJ, Rotenberg N. Reconfigurable quantum photonic circuits based on quantum dots. NANOPHOTONICS 2024; 13:2951-2959. [PMID: 39006136 PMCID: PMC11245123 DOI: 10.1515/nanoph-2024-0044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 04/23/2024] [Indexed: 07/16/2024]
Abstract
Quantum photonic integrated circuits, composed of linear-optical elements, offer an efficient way for encoding and processing quantum information on-chip. At their core, these circuits rely on reconfigurable phase shifters, typically constructed from classical components such as thermo- or electro-optical materials, while quantum solid-state emitters such as quantum dots are limited to acting as single-photon sources. Here, we demonstrate the potential of quantum dots as reconfigurable phase shifters. We use numerical models based on established literature parameters to show that circuits utilizing these emitters enable high-fidelity operation and are scalable. Despite the inherent imperfections associated with quantum dots, such as imperfect coupling, dephasing, or spectral diffusion, we show that circuits based on these emitters may be optimized such that these do not significantly impact the unitary infidelity. Specifically, they do not increase the infidelity by more than 0.001 in circuits with up to 10 modes, compared to those affected only by standard nanophotonic losses and routing errors. For example, we achieve fidelities of 0.9998 in quantum-dot-based circuits enacting controlled-phase and - not gates without any redundancies. These findings demonstrate the feasibility of quantum emitter-driven quantum information processing and pave the way for cryogenically-compatible, fast, and low-loss reconfigurable quantum photonic circuits.
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Affiliation(s)
- Adam McCaw
- Centre for Nanophotonics, Department of Physics, Engineering Physics & Astronomy, Queen’s University, 64 Bader Lane, K7L 3N6, Kingston, Ontario, Canada
| | - Jacob Ewaniuk
- Centre for Nanophotonics, Department of Physics, Engineering Physics & Astronomy, Queen’s University, 64 Bader Lane, K7L 3N6, Kingston, Ontario, Canada
| | - Bhavin J. Shastri
- Centre for Nanophotonics, Department of Physics, Engineering Physics & Astronomy, Queen’s University, 64 Bader Lane, K7L 3N6, Kingston, Ontario, Canada
- Vector Institute, M5G 1M1, Toronto, Ontario, Canada
| | - Nir Rotenberg
- Centre for Nanophotonics, Department of Physics, Engineering Physics & Astronomy, Queen’s University, 64 Bader Lane, K7L 3N6, Kingston, Ontario, Canada
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2
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Zhou L, Xu Q, Feng T, Zhou X. Experimental realization of a three-photon asymmetric maximally entangled state and its application to quantum state transfer. SCIENCE ADVANCES 2024; 10:eadj9251. [PMID: 38905347 DOI: 10.1126/sciadv.adj9251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 05/16/2024] [Indexed: 06/23/2024]
Abstract
Quantum entanglement is crucial for quantum information processing, prominently used in quantum communication, computation, and metrology. Recent studies have shifted toward high-dimensional entangled states, offering greater information capacity and enabling more complex applications. Here, we experimentally prepared a three-photon asymmetric maximally entangled state, comprising two two-dimensional photons and one four-dimensional photon. Using this state, we conducted a proof-of-principle experiment, successfully transferring a four-dimensional quantum state from two photons to another photon with fidelities ranging from 0.78 to 0.86. These results exceed theoretical limits, demonstrating genuine four-dimensional quantum state transfer. The asymmetric entangled state demonstrated here holds promise for future quantum networks as a quantum interface facilitating information transfer across quantum systems with different dimensions.
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Affiliation(s)
- Linxiang Zhou
- State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics, Sun Yat-sen University, Guangzhou 510000, People's Republic of China
| | - Qiao Xu
- State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics, Sun Yat-sen University, Guangzhou 510000, People's Republic of China
| | - Tianfeng Feng
- State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics, Sun Yat-sen University, Guangzhou 510000, People's Republic of China
| | - Xiaoqi Zhou
- State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics, Sun Yat-sen University, Guangzhou 510000, People's Republic of China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, People's Republic of China
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3
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Wang YD, Zhang ZY, Chen Y, Sun YK, Li YC, Tian ZN, Ren XF, Chen QD, Guo GC. Arbitrarily rotated optical axis waveguide induced by a trimming line. OPTICS LETTERS 2023; 48:3063-3066. [PMID: 37262281 DOI: 10.1364/ol.493410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 05/18/2023] [Indexed: 06/03/2023]
Abstract
Rotated optical axis waveguides can facilitate on-chip arbitrary wave-plate operations, which are crucial tools for developing integrated universal quantum computing algorithms. In this paper, we propose a unique technique based on femtosecond laser direct writing technology to fabricate arbitrarily rotated optical axis waveguides. First, a circular isotropic main waveguide with a non-optical axis was fabricated using a beam shaping method. Thereafter, a trimming line was used to create an artificial stress field near the main waveguide to induce a rotated optical axis. Using this technique, we fabricated high-performance half- and quarter-wave plates. Subsequently, high-fidelity (97.1%) Pauli-X gate operation was demonstrated via quantum process tomography, which constitutes the basis for the full manipulation of on-chip polarization-encoded qubits. In the future, this work is expected to lead to new prospects for polarization-encoded information in photonic integrated circuits.
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Yin XF, Yao XC, Wu B, Fei YY, Mao Y, Zhang R, Liu LZ, Wang Z, Li L, Liu NL, Wilczek F, Chen YA, Pan JW. Solving independent set problems with photonic quantum circuits. Proc Natl Acad Sci U S A 2023; 120:e2212323120. [PMID: 37216545 PMCID: PMC10235971 DOI: 10.1073/pnas.2212323120] [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: 08/08/2022] [Accepted: 03/01/2023] [Indexed: 05/24/2023] Open
Abstract
An independent set (IS) is a set of vertices in a graph such that no edge connects any two vertices. In adiabatic quantum computation [E. Farhi, et al., Science 292, 472-475 (2001); A. Das, B. K. Chakrabarti, Rev. Mod. Phys. 80, 1061-1081 (2008)], a given graph G(V, E) can be naturally mapped onto a many-body Hamiltonian [Formula: see text], with edges [Formula: see text] being the two-body interactions between adjacent vertices [Formula: see text]. Thus, solving the IS problem is equivalent to finding all the computational basis ground states of [Formula: see text]. Very recently, non-Abelian adiabatic mixing (NAAM) has been proposed to address this task, exploiting an emergent non-Abelian gauge symmetry of [Formula: see text] [B. Wu, H. Yu, F. Wilczek, Phys. Rev. A 101, 012318 (2020)]. Here, we solve a representative IS problem [Formula: see text] by simulating the NAAM digitally using a linear optical quantum network, consisting of three C-Phase gates, four deterministic two-qubit gate arrays (DGA), and ten single rotation gates. The maximum IS has been successfully identified with sufficient Trotterization steps and a carefully chosen evolution path. Remarkably, we find IS with a total probability of 0.875(16), among which the nontrivial ones have a considerable weight of about 31.4%. Our experiment demonstrates the potential advantage of NAAM for solving IS-equivalent problems.
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Affiliation(s)
- Xu-Fei Yin
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Xing-Can Yao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Biao Wu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
| | - Yue-Yang Fei
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Yingqiu Mao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Rui Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Li-Zheng Liu
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Zhenduo Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing100871, China
| | - Li Li
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Nai-Le Liu
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Frank Wilczek
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
- Center for Theoretical Physics, MIT, Cambridge, MA02139
- T. D. Lee Institute, Shanghai Jiao Tong University, Shanghai200240, China
- Department of Physics, Stockholm University, StockholmSE-106 91, Sweden
- Department of Physics and Origins Project, Arizona State University, Tempe, AZ25287
| | - Yu-Ao Chen
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
| | - Jian-Wei Pan
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei230088, China
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5
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Nguyen HT, Yen ZL, Su YH, Hsieh YP, Hofmann M. 2D Material-Enabled Optical Rectennas with Ultrastrong Light-Electron Coupling. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202199. [PMID: 35869608 DOI: 10.1002/smll.202202199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Optical rectennas extend the electromagnetic wave rectification process into the visible regime and provide a route toward high-performance photodetection and energy harvesting. Here, the promise of 2D materials toward on-chip optical rectennas is demonstrated. A self-aligned patterning process yields lateral MIM structures where a nanometer-sized air gap separates a 2D material contact from a metal electrode. This device can be scalably produced in large arrays using established microfabrication techniques. Different from previous approaches, the performance of the 2D rectenna can be adjusted through electrostatic gating. Optimization of the band alignment leads to strong rectification at wavelengths around 500 nm and clear polarization control. Comparison of wavelength-dependent rectenna performance with a photon-assisted tunneling model reveals a tenfold increase in photon-electron coupling over nanotube-based rectennas. The results highlight the potential of 2D material-based rectennas for future quantum computing applications.
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Affiliation(s)
- Hai-Thai Nguyen
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Zhi-Long Yen
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Yen-Hsun Su
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Ya-Ping Hsieh
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Mario Hofmann
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
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6
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High-fidelity photonic quantum logic gate based on near-optimal Rydberg single-photon source. Nat Commun 2022; 13:4454. [PMID: 35915059 PMCID: PMC9343406 DOI: 10.1038/s41467-022-32083-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/13/2022] [Indexed: 11/25/2022] Open
Abstract
Compared to other types of qubits, photon is one of a kind due to its unparalleled advantages in long-distance quantum information exchange. Therefore, photon is a natural candidate for building a large-scale, modular optical quantum computer operating at room temperature. However, low-fidelity two-photon quantum logic gates and their probabilistic nature result in a large resource overhead for fault tolerant quantum computation. While the probabilistic problem can, in principle, be solved by employing multiplexing and error correction, the fidelity of linear-optical quantum logic gate is limited by the imperfections of single photons. Here, we report the demonstration of a linear-optical quantum logic gate with truth table fidelity of 99.84(3)% and entangling gate fidelity of 99.69(4)% post-selected upon the detection of photons. The achieved high gate fidelities are made possible by our near-optimal Rydberg single-photon source. Our work paves the way for scalable photonic quantum applications based on near-optimal single-photon qubits and photon-photon gates. The current main source of errors for photonic quantum logic gates is the imperfections of the single photons. Here, by using high-quality photons from Rydberg atoms, the authors are able to reach 99.7% entangling gate fidelity in a photonic CNOT gate.
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7
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Zhai L, Nguyen GN, Spinnler C, Ritzmann J, Löbl MC, Wieck AD, Ludwig A, Javadi A, Warburton RJ. Quantum interference of identical photons from remote GaAs quantum dots. NATURE NANOTECHNOLOGY 2022; 17:829-833. [PMID: 35589820 DOI: 10.1038/s41565-022-01131-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/01/2022] [Indexed: 06/15/2023]
Abstract
Photonic quantum technology provides a viable route to quantum communication1,2, quantum simulation3 and quantum information processing4. Recent progress has seen the realization of boson sampling using 20 single photons3 and quantum key distribution over hundreds of kilometres2. Scaling the complexity requires architectures containing multiple photon sources, photon counters and a large number of indistinguishable single photons. Semiconductor quantum dots are bright and fast sources of coherent single photons5-9. For applications, a roadblock is the poor quantum coherence on interfering single photons created by independent quantum dots10,11. Here we demonstrate two-photon interference with near-unity visibility (93.0 ± 0.8)% using photons from two completely separate GaAs quantum dots. The experiment retains all the emission into the zero phonon line-only the weak phonon sideband is rejected; temporal post-selection is not employed. By exploiting quantum interference, we demonstrate a photonic controlled-not circuit and an entanglement with fidelity of (85.0 ± 1.0)% between photons of different origins. The two-photon interference visibility is high enough that the entanglement fidelity is well above the classical threshold. The high mutual coherence of the photons stems from high-quality materials, diode structure and relatively large quantum dot size. Our results establish a platform-GaAs quantum dots-for creating coherent single photons in a scalable way.
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Affiliation(s)
- Liang Zhai
- Department of Physics, University of Basel, Basel, Switzerland.
| | - Giang N Nguyen
- Department of Physics, University of Basel, Basel, Switzerland
| | | | - Julian Ritzmann
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Matthias C Löbl
- Department of Physics, University of Basel, Basel, Switzerland
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Alisa Javadi
- Department of Physics, University of Basel, Basel, Switzerland
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8
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He RD, Wu KD, Xiang GY, Li CF, Guo GC. Experimental quantification of dynamical coherence via entangling two qubits. OPTICS EXPRESS 2022; 30:10346-10353. [PMID: 35473004 DOI: 10.1364/oe.453504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
Coherence and entanglement are both the fundamental properties which quantify the degree of nonclassicality possessed in a quantum state. Recently coherence and entanglement are considered as a dynamical resource where the nonclassicality is strongly related to the amount of the static resources which can be generated in a quantum process. In [Phys. Rev. Lett.125, 130401 (2020)10.1103/PhysRevLett.125.130401], for the first time, the authors study the interconvertability of these two kinds of dynamical resources. Here, we demonstrate this resource conversion in an all optical setup, and successfully observe the dynamical resource conversion. The experimental observation prove the ability of manipulating dynamical resource within current quantum photonic technologies.
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9
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Feng LT, Zhang M, Xiong X, Liu D, Cheng YJ, Jing FM, Qi XZ, Chen Y, He DY, Guo GP, Guo GC, Dai DX, Ren XF. Transverse Mode-Encoded Quantum Gate on a Silicon Photonic Chip. PHYSICAL REVIEW LETTERS 2022; 128:060501. [PMID: 35213196 DOI: 10.1103/physrevlett.128.060501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
As an important degree of freedom (d.o.f.) in photonic integrated circuits, the orthogonal transverse mode provides a promising and flexible way to increase communication capability, for both classical and quantum information processing. To construct large-scale on-chip multimode multi-d.o.f.s quantum systems, a transverse mode-encoded controlled-NOT (CNOT) gate is necessary. Here, with the help of our new transverse mode-dependent directional coupler and attenuator, we demonstrate the first multimode implementation of a 2-qubit quantum gate. The ability of the gate is demonstrated by entangling two separated transverse mode qubits with an average fidelity of 0.89±0.02 and the achievement of 10 standard deviations of violations in the quantum nonlocality verification. In addition, a fidelity of 0.82±0.01 is obtained from quantum process tomography used to completely characterize the CNOT gate. Our work paves the way for universal transverse mode-encoded quantum operations and large-scale multimode multi-d.o.f.s quantum systems.
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Affiliation(s)
- Lan-Tian Feng
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Ming Zhang
- State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
- Ningbo Research Institute, Zhejiang University, Ningbo 315100, China
| | - Xiao Xiong
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Di Liu
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Jie Cheng
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Fang-Ming Jing
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xiao-Zhuo Qi
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yang Chen
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - De-Yong He
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Guo-Ping Guo
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Dao-Xin Dai
- State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
- Ningbo Research Institute, Zhejiang University, Ningbo 315100, China
| | - Xi-Feng Ren
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
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Li JP, Gu X, Qin J, Wu D, You X, Wang H, Schneider C, Höfling S, Huo YH, Lu CY, Liu NL, Li L, Pan JW. Heralded Nondestructive Quantum Entangling Gate with Single-Photon Sources. PHYSICAL REVIEW LETTERS 2021; 126:140501. [PMID: 33891463 DOI: 10.1103/physrevlett.126.140501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
Heralded entangling quantum gates are an essential element for the implementation of large-scale optical quantum computation. Yet, the experimental demonstration of genuine heralded entangling gates with free-flying output photons in linear optical system, was hindered by the intrinsically probabilistic source and double-pair emission in parametric down-conversion. Here, by using an on-demand single-photon source based on a semiconductor quantum dot embedded in a micropillar cavity, we demonstrate a heralded controlled-NOT (CNOT) operation between two single photons for the first time. To characterize the performance of the CNOT gate, we estimate its average quantum gate fidelity of (87.8±1.2)%. As an application, we generated event-ready Bell states with a fidelity of (83.4±2.4)%. Our results are an important step towards the development of photon-photon quantum logic gates.
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Affiliation(s)
- Jin-Peng Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Xuemei Gu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Jian Qin
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Dian Wu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Xiang You
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Hui Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Christian Schneider
- Institute of Physics, Carl von Ossietzky University, 26129 Oldenburg, Germany
- Technische Physik, Physikalische Institut and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Sven Höfling
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- Technische Physik, Physikalische Institut and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Yong-Heng Huo
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Chao-Yang Lu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Nai-Le Liu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Li Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Jian-Wei Pan
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
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11
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Guo Q, Zhao YY, Grassl M, Nie X, Xiang GY, Xin T, Yin ZQ, Zeng B. Testing a quantum error-correcting code on various platforms. Sci Bull (Beijing) 2021; 66:29-35. [PMID: 36654309 DOI: 10.1016/j.scib.2020.07.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 06/02/2020] [Accepted: 07/20/2020] [Indexed: 01/20/2023]
Abstract
Quantum error correction plays an important role in fault-tolerant quantum information processing. It is usually difficult to experimentally realize quantum error correction, as it requires multiple qubits and quantum gates with high fidelity. Here we propose a simple quantum error-correcting code for the detected amplitude damping channel. The code requires only two qubits. We implement the encoding, the channel, and the recovery on an optical platform, the IBM Q System, and a nuclear magnetic resonance system. For all of these systems, the error correction advantage appears when the damping rate exceeds some threshold. We compare the features of these quantum information processing systems used and demonstrate the advantage of quantum error correction on current quantum computing platforms.
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Affiliation(s)
- Qihao Guo
- Institute for Quantum Computing, Baidu Research, Beijing 100193, China; Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China; Center for Quantum Computing, Peng Cheng Laboratory, Shenzhen 518055, China
| | - Yuan-Yuan Zhao
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Center for Quantum Computing, Peng Cheng Laboratory, Shenzhen 518055, China
| | - Markus Grassl
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany; International Centre for Theory of Quantum Technologies, 80-308 Gdańsk, Poland
| | - Xinfang Nie
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guo-Yong Xiang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China.
| | - Tao Xin
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Zhang-Qi Yin
- Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE),School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Bei Zeng
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
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12
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Stárek R, Mičuda M, Hošák R, Ježek M, Fiurášek J. Experimental entanglement-assisted weak measurement of phase shift. OPTICS EXPRESS 2020; 28:34639-34655. [PMID: 33182927 DOI: 10.1364/oe.403711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/14/2020] [Indexed: 06/11/2023]
Abstract
Weak value amplification is a popular method in quantum metrology for enhancing the sensitivity at the expense of the signal intensity. Recently, it was suggested that the trade-off between signal intensity and sensitivity can be improved by using an entangled auxiliary system. Here, we experimentally investigate such entanglement-assisted weak measurement of small conditional phase shifts induced by an interaction between ancilla and meter qubits. We utilize entangled photon pairs and implement the required three-qubit quantum logic circuit with linear optics. The circuit comprises a two-qubit controlled phase gate and a three-qubit controlled-controlled phase gate with fully tunable conditional phase shifts. We fully characterize the output states of our circuit by quantum state tomography and perform a comprehensive analysis of the trade-off between the measurement sensitivity and the success probability of the protocol. The observed experimental results are in good qualitative agreement with theoretical predictions, but the overall performance of our setup is limited by various experimental imperfections. We provide a detailed theoretical analysis of the influence of dephasing of the entangled ancilla state, which is one of the main sources of imperfections in the experiment. We also discuss the ultimate scaling with the dimension of the entangled ancilla system.
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13
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14
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Kim Y, Teo YS, Ahn D, Im DG, Cho YW, Leuchs G, Sánchez-Soto LL, Jeong H, Kim YH. Universal Compressive Characterization of Quantum Dynamics. PHYSICAL REVIEW LETTERS 2020; 124:210401. [PMID: 32530676 DOI: 10.1103/physrevlett.124.210401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Recent quantum technologies utilize complex multidimensional processes that govern the dynamics of quantum systems. We develop an adaptive diagonal-element-probing compression technique that feasibly characterizes any unknown quantum processes using much fewer measurements compared to conventional methods. This technique utilizes compressive projective measurements that are generalizable to an arbitrary number of subsystems. Both numerical analysis and experimental results with unitary gates demonstrate low measurement costs, of order O(d^{2}) for d-dimensional systems, and robustness against statistical noise. Our work potentially paves the way for a reliable and highly compressive characterization of general quantum devices.
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Affiliation(s)
- Yosep Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
| | - Yong Siah Teo
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Daekun Ahn
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Dong-Gil Im
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
| | - Young-Wook Cho
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), 02792 Seoul, Korea
| | - Gerd Leuchs
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Institute of Applied Physics, Russian Academy of Sciences, 603950 Nizhny Novgorod, Russia
| | - Luis L Sánchez-Soto
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Departamento de Óptica, Facultad de Física, Universidad Complutense, 28040 Madrid, Spain
| | - Hyunseok Jeong
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Yoon-Ho Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
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15
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Abstract
One of the central problems in quantum theory is to characterize, detect, and quantify quantumness in terms of classical strategies. Dephasing processes, caused by non-dissipative information exchange between quantum systems and environments, provides a natural platform for this purpose, as they control the quantum-to-classical transition. Recently, it has been shown that dephasing dynamics itself can exhibit (non)classical traits, depending on the nature of the system-environment correlations and the related (im)possibility to simulate these dynamics with Hamiltonian ensembles–the classical strategy. Here we establish the framework of detecting and quantifying the nonclassicality for pure dephasing dynamics. The uniqueness of the canonical representation of Hamiltonian ensembles is shown, and a constructive method to determine the latter is presented. We illustrate our method for qubit, qutrit, and qubit-pair pure dephasing and describe how to implement our approach with quantum process tomography experiments. Our work is readily applicable to present-day quantum experiments. The presence of processes that cannot be simulated classically in open quantum system dynamics is acknowledged, but an exact quantifier for this non-classical character is still missing. Here, the authors provide a quantitative measure of non-classicality for purely dephasing evolutions.
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16
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Mancino L, Cavina V, De Pasquale A, Sbroscia M, Booth RI, Roccia E, Gianani I, Giovannetti V, Barbieri M. Geometrical Bounds on Irreversibility in Open Quantum Systems. PHYSICAL REVIEW LETTERS 2018; 121:160602. [PMID: 30387653 DOI: 10.1103/physrevlett.121.160602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 08/01/2018] [Indexed: 06/08/2023]
Abstract
The Clausius inequality has deep implications for reversibility and the arrow of time. Quantum theory is able to extend this result for closed systems by inspecting the trajectory of the density matrix on its manifold. Here we show that this approach can provide an upper and lower bound to the irreversible entropy production for open quantum systems as well. These provide insights on how the information on the initial state is forgotten through a thermalization process. Limits of the applicability of our bounds are discussed and demonstrated in a quantum photonic simulator.
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Affiliation(s)
- Luca Mancino
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
| | - Vasco Cavina
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
| | - Antonella De Pasquale
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
- Dipartimento di Fisica, Università di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino (FI), Italy
- INFN Sezione di Firenze, via G.Sansone 1, I-50019 Sesto Fiorentino (FI), Italy
| | - Marco Sbroscia
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
| | - Robert I Booth
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
- Institut de Physique, Sorbonne Université, 4 Place Jussieu, 75005, Paris, France
| | - Emanuele Roccia
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
| | - Ilaria Gianani
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
| | - Vittorio Giovannetti
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
| | - Marco Barbieri
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
- Istituto Nazionale di Ottica-CNR, Largo Enrico Fermi 6, 50125, Florence, Italy
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17
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Wu KD, Hou Z, Zhao YY, Xiang GY, Li CF, Guo GC, Ma J, He QY, Thompson J, Gu M. Experimental Cyclic Interconversion between Coherence and Quantum Correlations. PHYSICAL REVIEW LETTERS 2018; 121:050401. [PMID: 30118306 DOI: 10.1103/physrevlett.121.050401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 03/12/2018] [Indexed: 06/08/2023]
Abstract
Quantum resource theories seek to quantify sources of nonclassicality that bestow quantum technologies their operational advantage. Chief among these are studies of quantum correlations and quantum coherence. The former isolates nonclassicality in the correlations between systems, and the latter captures nonclassicality of quantum superpositions within a single physical system. Here, we present a scheme that cyclically interconverts between these resources without loss. The first stage converts coherence present in an input system into correlations with an ancilla. The second stage harnesses these correlations to restore coherence on the input system by measurement of the ancilla. We experimentally demonstrate this interconversion process using linear optics. Our experiment highlights the connection between nonclassicality of correlations and nonclassicality within local quantum systems and provides potential flexibilities in exploiting one resource to perform tasks normally associated with the other.
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Affiliation(s)
- Kang-Da Wu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Peoples Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Zhibo Hou
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Peoples Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Yuan-Yuan Zhao
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Peoples Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Guo-Yong Xiang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Peoples Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Chuan-Feng Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Peoples Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Peoples Republic of China
- University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Jiajun Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Qiong-Yi He
- State Key Laboratory of Mesoscopic Physics, School of Physics, Peking University, Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Jayne Thompson
- Centre for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore
| | - Mile Gu
- Centre for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore
- School of Mathematical and Physical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Complexity Institute, Nanyang Technological University, Singapore 637335, Singapore
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18
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Stárek R, Miková M, Straka I, Dušek M, Ježek M, Fiurášek J, Mičuda M. Experimental realization of SWAP operation on hyper-encoded qubits. OPTICS EXPRESS 2018; 26:8443-8452. [PMID: 29715811 DOI: 10.1364/oe.26.008443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/15/2018] [Indexed: 06/08/2023]
Abstract
Hyper-encoding enables storing several qubits in a single photon using its different degrees of freedom like polarization and spatial ones. This approach enables feasible implementation of multi-qubit operations. One of the basic manipulations of two or more qubits is to swap their quantum state. Here we report on feasible and stable experimental implementation of a deterministic single photon two-qubit SWAP gate that interchanges path and polarization qubits. We discuss the principle of its operation and give detailed information about experimental demonstration employing two Mach-Zehnder interferometers with one common arm. The gate characterization is done by full quantum process tomography using photons produced by heralded single-photon source. The achieved quantum process fidelity reached more than 0.94 with an effective phase uncertainty of the whole setup, evaluated by means of Allan deviation, below 2.5 deg for 2.5 h without any active stabilization. Our design provides a contribution to the hyper-encoded linear quantum optics toolbox.
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19
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Flórez J, Carlson NJ, Nacke CH, Giner L, Lundeen JS. A variable partially polarizing beam splitter. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:023108. [PMID: 29495806 DOI: 10.1063/1.5004805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present designs for variably polarizing beam splitters. These are beam splitters allowing the complete and independent control of the horizontal and vertical polarization splitting ratios. They have quantum optics and quantum information applications, such as quantum logic gates for quantum computing and non-local measurements for quantum state estimation. At the heart of each design is an interferometer. We experimentally demonstrate one particular implementation, a displaced Sagnac interferometer configuration, that provides an inherent instability to air currents and vibrations. Furthermore, this design does not require any custom-made optics but only common components which can be easily found in an optics laboratory.
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Affiliation(s)
- Jefferson Flórez
- Department of Physics and Centre for Research in Photonics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Nathan J Carlson
- Department of Physics and Centre for Research in Photonics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Codey H Nacke
- Department of Physics and Centre for Research in Photonics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Lambert Giner
- Department of Physics and Centre for Research in Photonics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Jeff S Lundeen
- Department of Physics and Centre for Research in Photonics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
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20
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Direct quantum process tomography via measuring sequential weak values of incompatible observables. Nat Commun 2018; 9:192. [PMID: 29335489 PMCID: PMC5768737 DOI: 10.1038/s41467-017-02511-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 12/06/2017] [Indexed: 11/09/2022] Open
Abstract
The weak value concept has enabled fundamental studies of quantum measurement and, recently, found potential applications in quantum and classical metrology. However, most weak value experiments reported to date do not require quantum mechanical descriptions, as they only exploit the classical wave nature of the physical systems. In this work, we demonstrate measurement of the sequential weak value of two incompatible observables by making use of two-photon quantum interference so that the results can only be explained quantum physically. We then demonstrate that the sequential weak value measurement can be used to perform direct quantum process tomography of a qubit channel. Our work not only demonstrates the quantum nature of weak values but also presents potential new applications of weak values in analyzing quantum channels and operations.
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21
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Wang FX, Wu J, Chen W, Yin ZQ, Wang S, Guo GC, Han ZF. Controlled-phase manipulation module for orbital-angular-momentum photon states. OPTICS LETTERS 2018; 43:349-352. [PMID: 29328278 DOI: 10.1364/ol.43.000349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/15/2017] [Indexed: 06/07/2023]
Abstract
Phase manipulation is essential to quantum information processing, for which the orbital angular momentum (OAM) of photon is a promising high-dimensional resource. Dove prism (DP) is one of the most important elements to realize the nondestructive phase manipulation of OAM photons. DP usually changes the polarization of light and thus increases the manipulation error for a spin-OAM hybrid state. DP in a Sagnac interferometer also introduces a mode-dependent global phase to the OAM mode. In this work, we implemented a high-dimensional controlled-phase manipulation module (PMM), which can compensate the mode-dependent global phase and thus preserve the phase in the spin-OAM hybrid superposition state. The PMM is stable for free running and is suitable to realize the high-dimensional controlled-phase gate for spin-OAM hybrid states. Considering the Sagnac-based structure, the PMM is also suitable for classical communication with the spin-OAM hybrid light field.
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22
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Huang HL, Zhao Q, Ma X, Liu C, Su ZE, Wang XL, Li L, Liu NL, Sanders BC, Lu CY, Pan JW. Experimental Blind Quantum Computing for a Classical Client. PHYSICAL REVIEW LETTERS 2017; 119:050503. [PMID: 28949702 DOI: 10.1103/physrevlett.119.050503] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 06/07/2023]
Abstract
To date, blind quantum computing demonstrations require clients to have weak quantum devices. Here we implement a proof-of-principle experiment for completely classical clients. Via classically interacting with two quantum servers that share entanglement, the client accomplishes the task of having the number 15 factorized by servers who are denied information about the computation itself. This concealment is accompanied by a verification protocol that tests servers' honesty and correctness. Our demonstration shows the feasibility of completely classical clients and thus is a key milestone towards secure cloud quantum computing.
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Affiliation(s)
- He-Liang Huang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- Henan Key Laboratory of Quantum Information and Cryptography, Zhengzhou Information Science and Technology Institute, Zhengzhou, Henan 450000, China
| | - Qi Zhao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Xiongfeng Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Chang Liu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Zu-En Su
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Xi-Lin Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Li Li
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Nai-Le Liu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Barry C Sanders
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- Institute for Quantum Science and Technology, University of Calgary, Alberta T2N 1N4, Canada
- Program in Quantum Information Science, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1M1, Canada
| | - Chao-Yang Lu
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Jian-Wei Pan
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, CAS Centre for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
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23
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Zheng Y, Song C, Chen MC, Xia B, Liu W, Guo Q, Zhang L, Xu D, Deng H, Huang K, Wu Y, Yan Z, Zheng D, Lu L, Pan JW, Wang H, Lu CY, Zhu X. Solving Systems of Linear Equations with a Superconducting Quantum Processor. PHYSICAL REVIEW LETTERS 2017; 118:210504. [PMID: 28598660 DOI: 10.1103/physrevlett.118.210504] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Indexed: 06/07/2023]
Abstract
Superconducting quantum circuits are a promising candidate for building scalable quantum computers. Here, we use a four-qubit superconducting quantum processor to solve a two-dimensional system of linear equations based on a quantum algorithm proposed by Harrow, Hassidim, and Lloyd [Phys. Rev. Lett. 103, 150502 (2009)PRLTAO0031-900710.1103/PhysRevLett.103.150502], which promises an exponential speedup over classical algorithms under certain circumstances. We benchmark the solver with quantum inputs and outputs, and characterize it by nontrace-preserving quantum process tomography, which yields a process fidelity of 0.837±0.006. Our results highlight the potential of superconducting quantum circuits for applications in solving large-scale linear systems, a ubiquitous task in science and engineering.
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Affiliation(s)
- Yarui Zheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chao Song
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ming-Cheng Chen
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Benxiang Xia
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Wuxin Liu
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Qiujiang Guo
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Libo Zhang
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Da Xu
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Hui Deng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Keqiang Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yulin Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhiguang Yan
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Dongning Zheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Lu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jian-Wei Pan
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - H Wang
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chao-Yang Lu
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Xiaobo Zhu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
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24
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Mičuda M, Koutný D, Miková M, Straka I, Ježek M, Mišta L. Experimental demonstration of a fully inseparable quantum state with nonlocalizable entanglement. Sci Rep 2017; 7:45045. [PMID: 28344336 PMCID: PMC5366861 DOI: 10.1038/srep45045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/20/2017] [Indexed: 11/09/2022] Open
Abstract
Localizability of entanglement in fully inseparable states is a key ingredient of assisted quantum information protocols as well as measurement-based models of quantum computing. We investigate the existence of fully inseparable states with nonlocalizable entanglement, that is, with entanglement which cannot be localized between any pair of subsystems by any measurement on the remaining part of the system. It is shown, that the nonlocalizable entanglement occurs already in suitable mixtures of a three-qubit GHZ state and white noise. Further, we generalize this set of states to a two-parametric family of fully inseparable three-qubit states with nonlocalizable entanglement. Finally, we demonstrate experimentally the existence of nonlocalizable entanglement by preparing and characterizing one state from the family using correlated single photons and linear optical circuit.
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Affiliation(s)
- M Mičuda
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - D Koutný
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - M Miková
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - I Straka
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - M Ježek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - L Mišta
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
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25
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Abstract
Game theory is a well established branch of mathematics whose formalism has a vast range of applications from the social sciences, biology, to economics. Motivated by quantum information science, there has been a leap in the formulation of novel game strategies that lead to new (quantum Nash) equilibrium points whereby players in some classical games are always outperformed if sharing and processing joint information ruled by the laws of quantum physics is allowed. We show that, for a bipartite non zero-sum game, input local quantum correlations, and separable states in particular, suffice to achieve an advantage over any strategy that uses classical resources, thus dispensing with quantum nonlocality, entanglement, or even discord between the players' input states. This highlights the remarkable key role played by pure quantum coherence at powering some protocols. Finally, we propose an experiment that uses separable states and basic photon interferometry to demonstrate the locally-correlated quantum advantage.
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26
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Yang R, Li J, Song XB, Gao T, Li YR, Zhang YJ, Chen XX, Gong YX. Experimental realization of a 2 × 2 polarization-independent split-ratio-tunable optical beam splitter. OPTICS EXPRESS 2016; 24:28519-28528. [PMID: 27958496 DOI: 10.1364/oe.24.028519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We realized a polarization-independent split-ratio-tunable optical beam splitter supporting two input and output ports through a stable interferometer. By adjusting the angle of a half-wave plate in the interferometer, we can tune the beam splitter reflectivities for both input ports from 0 to 1, regardless of the input light polarization. High-fidelity polarization-preserving transmission from input to output ports was verified by complete quantum process tomography. Nearly optimal interference effects at the beam splitter with various split ratios were observed by two-photon Hong-Ou-Mandel interference for different input polarization states. Such a beam splitter could find a variety of applications in classical and quantum optical technologies.
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27
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Okamoto R, Takeuchi S. Experimental demonstration of a quantum shutter closing two slits simultaneously. Sci Rep 2016; 6:35161. [PMID: 27739465 PMCID: PMC5064380 DOI: 10.1038/srep35161] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 09/26/2016] [Indexed: 11/09/2022] Open
Abstract
The interference between two paths of a single photon at a double slit is widely considered to be the most paradoxical result of quantum theory. Here is a new interesting question to the phenomenon: can a single shutter simultaneously close two slits by effectively being in a superposition of different locations? Aharonov and Vaidman have shown that it is indeed possible to construct a quantum shutter that can close two slits and reflect a probe photon perfectly when its initial and final states are appropriately selected. Here we report the experimental demonstration of their proposal overcoming the difficulty to realize a 'quantum shutter' by employing photonic quantum routers. The reflectance ratio of 0.61 ± 0.027 surpasses the classical limit with 4.1 standard deviation, shedding new light on the unusual physical properties of quantum operations. This experimental demonstration, where the strong measurement and non-local superposition seem co-existing, provides an alternative to weak measurements as a way to explore the nature of quantum physics.
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Affiliation(s)
- Ryo Okamoto
- Kyoto University, Department of Electronic Science and Engineering, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shigeki Takeuchi
- Kyoto University, Department of Electronic Science and Engineering, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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28
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Stárek R, Mičuda M, Miková M, Straka I, Dušek M, Ježek M, Fiurášek J. Experimental investigation of a four-qubit linear-optical quantum logic circuit. Sci Rep 2016; 6:33475. [PMID: 27647176 PMCID: PMC5028834 DOI: 10.1038/srep33475] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 08/30/2016] [Indexed: 11/24/2022] Open
Abstract
We experimentally demonstrate and characterize a four-qubit linear-optical quantum logic circuit. Our robust and versatile scheme exploits encoding of two qubits into polarization and path degrees of single photons and involves two crossed inherently stable interferometers. This approach allows us to design a complex quantum logic circuit that combines a genuine four-qubit C(3)Z gate and several two-qubit and single-qubit gates. The C(3)Z gate introduces a sign flip if and only if all four qubits are in the computational state |1〉. We verify high-fidelity performance of this central four-qubit gate using Hofmann bounds on quantum gate fidelity and Monte Carlo fidelity sampling. We also experimentally demonstrate that the quantum logic circuit can generate genuine multipartite entanglement and we certify the entanglement with the use of suitably tailored entanglement witnesses.
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Affiliation(s)
- R. Stárek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - M. Mičuda
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - M. Miková
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - I. Straka
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - M. Dušek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - M. Ježek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - J. Fiurášek
- Department of Optics, Palacký University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
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29
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Quantum computation based on photonic systems with two degrees of freedom assisted by the weak cross-Kerr nonlinearity. Sci Rep 2016; 6:29939. [PMID: 27424767 PMCID: PMC4947932 DOI: 10.1038/srep29939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/27/2016] [Indexed: 11/12/2022] Open
Abstract
Most of previous quantum computations only take use of one degree of freedom (DoF) of photons. An experimental system may possess various DoFs simultaneously. In this paper, with the weak cross-Kerr nonlinearity, we investigate the parallel quantum computation dependent on photonic systems with two DoFs. We construct nearly deterministic controlled-not (CNOT) gates operating on the polarization spatial DoFs of the two-photon or one-photon system. These CNOT gates show that two photonic DoFs can be encoded as independent qubits without auxiliary DoF in theory. Only the coherent states are required. Thus one half of quantum simulation resources may be saved in quantum applications if more complicated circuits are involved. Hence, one may trade off the implementation complexity and simulation resources by using different photonic systems. These CNOT gates are also used to complete various applications including the quantum teleportation and quantum superdense coding.
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30
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Lu H, Zhang Z, Chen LK, Li ZD, Liu C, Li L, Liu NL, Ma X, Chen YA, Pan JW. Secret Sharing of a Quantum State. PHYSICAL REVIEW LETTERS 2016; 117:030501. [PMID: 27472103 DOI: 10.1103/physrevlett.117.030501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Indexed: 06/06/2023]
Abstract
Secret sharing of a quantum state, or quantum secret sharing, in which a dealer wants to share a certain amount of quantum information with a few players, has wide applications in quantum information. The critical criterion in a threshold secret sharing scheme is confidentiality: with less than the designated number of players, no information can be recovered. Furthermore, in a quantum scenario, one additional critical criterion exists: the capability of sharing entangled and unknown quantum information. Here, by employing a six-photon entangled state, we demonstrate a quantum threshold scheme, where the shared quantum secrecy can be efficiently reconstructed with a state fidelity as high as 93%. By observing that any one or two parties cannot recover the secrecy, we show that our scheme meets the confidentiality criterion. Meanwhile, we also demonstrate that entangled quantum information can be shared and recovered via our setting, which shows that our implemented scheme is fully quantum. Moreover, our experimental setup can be treated as a decoding circuit of the five-qubit quantum error-correcting code with two erasure errors.
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Affiliation(s)
- He Lu
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Zhen Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Luo-Kan Chen
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Zheng-Da Li
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Chang Liu
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Li Li
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Nai-Le Liu
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Xiongfeng Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yu-Ao Chen
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Jian-Wei Pan
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
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31
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A 14 × 14 μm(2) footprint polarization-encoded quantum controlled-NOT gate based on hybrid waveguide. Nat Commun 2016; 7:11490. [PMID: 27142992 PMCID: PMC4857478 DOI: 10.1038/ncomms11490] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/01/2016] [Indexed: 11/08/2022] Open
Abstract
Photonic quantum information processing system has been widely used in communication, metrology and lithography. The recent emphasis on the miniaturized photonic platform is thus motivated by the urgent need for realizing large-scale information processing and computing. Although the integrated quantum logic gates and quantum algorithms based on path encoding have been successfully demonstrated, the technology for handling another commonly used polarization-encoded qubits has yet to be fully developed. Here, we show the implementation of a polarization-dependent beam-splitter in the hybrid waveguide system. With precisely design, the polarization-encoded controlled-NOT gate can be implemented using only single such polarization-dependent beam-splitter with the significant size reduction of the overall device footprint to 14 × 14 μm2. The experimental demonstration of the highly integrated controlled-NOT gate sets the stage to develop large-scale quantum information processing system. Our hybrid design also establishes the new capabilities in controlling the polarization modes in integrated photonic circuits. Photonic circuits often require separate components to manipulate light with orthogonal polarization, but this increases the chip size. Here, the authors create a polarization-dependent beam-splitter that uses dielectric loaded plasmonic waveguides to handle both polarizations in the same component.
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32
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GAZZANO OLIVIER, SOLOMON GLENNS. Toward optical quantum information processing with quantum dots coupled to microstructures [Invited]. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. B, OPTICAL PHYSICS 2016; 33:10.1364/josab.33.00c160. [PMID: 38881569 PMCID: PMC11177888 DOI: 10.1364/josab.33.00c160] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Major improvements have been made on semiconductor quantum dot light sources recently and now they can be seen as a serious candidate for near-future scalable photonic quantum information processing experiments. The three key parameters of these photon sources for such applications have been pushed to extreme values: almost unity single-photon purity and photon indistinguishability, and high brightness. In this paper, we review the progress achieved recently on quantum-dot-based single-photon sources. We also review some quantum information experiments where entanglement processes are achieved using semiconductor quantum dots.
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Affiliation(s)
- OLIVIER GAZZANO
- Joint Quantum Institute, National Institute of Standards and Technology & University of Maryland, Gaithersburg, Maryland 20899,USA
| | - GLENN S. SOLOMON
- Joint Quantum Institute, National Institute of Standards and Technology & University of Maryland, Gaithersburg, Maryland 20899,USA
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33
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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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34
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Highly Efficient Processing of Multi-photon States. Sci Rep 2015; 5:12792. [PMID: 26245489 PMCID: PMC4526856 DOI: 10.1038/srep12792] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 07/10/2015] [Indexed: 11/13/2022] Open
Abstract
How to implement multi-qubit gates is an important problem in quantum information processing. Based on cross phase modulation, we present an approach to realizing a family of multi-qubit gates that deterministically operate on single photons as the qubits. A general n-qubit unitary operation is a typical example of these gates. The approach greatly relax the requirement on the resources, such as the ancilla photons and coherent beams, as well as the number of operations on the qubits. The improvement in this framework may facilitate large scale quantum information processing.
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35
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Lemr K, Bartkiewicz K, Černoch A, Dušek M, Soubusta J. Experimental implementation of optimal linear-optical controlled-unitary gates. PHYSICAL REVIEW LETTERS 2015; 114:153602. [PMID: 25933314 DOI: 10.1103/physrevlett.114.153602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Indexed: 06/04/2023]
Abstract
We show that it is possible to reduce the number of two-qubit gates needed for the construction of an arbitrary controlled-unitary transformation by up to 2 times using a tunable controlled-phase gate. On the platform of linear optics, where two-qubit gates can only be achieved probabilistically, our method significantly reduces the amount of components and increases success probability of a two-qubit gate. The experimental implementation of our technique presented in this Letter for a controlled single-qubit unitary gate demonstrates that only one tunable controlled-phase gate is needed instead of two standard controlled-not gates. Thus, not only do we increase the success probability by about 1 order of magnitude (with the same resources), but also avoid the need for conducting quantum nondemolition measurement otherwise required to join two probabilistic gates. Subsequently, we generalize our method to a higher order, showing that n-times controlled gates can be optimized by replacing blocks of controlled-not gates with tunable controlled-phase gates.
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Affiliation(s)
- Karel Lemr
- RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Karol Bartkiewicz
- RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, 17. listopadu 12, 771 46 Olomouc, Czech Republic
- Faculty of Physics, Adam Mickiewicz University, PL-61-614 Poznań, Poland
| | - Antonín Černoch
- Institute of Physics of Academy of Sciences of the Czech Republic, Joint Laboratory of Optics of PU and IP AS CR, 17. listopadu 50A, 772 07 Olomouc, Czech Republic
| | - Miloslav Dušek
- Department of Optics, Faculty of Science, Palacký University, 17. listopadu 12, cz-77146 Olomouc, Czech Republic
| | - Jan Soubusta
- Institute of Physics of Academy of Sciences of the Czech Republic, Joint Laboratory of Optics of PU and IP AS CR, 17. listopadu 50A, 772 07 Olomouc, Czech Republic
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36
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Ionicioiu R, Jennewein T, Mann RB, Terno DR. Is wave-particle objectivity compatible with determinism and locality? Nat Commun 2014; 5:4997. [PMID: 25256419 PMCID: PMC5877209 DOI: 10.1038/ncomms5997] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 08/14/2014] [Indexed: 11/25/2022] Open
Abstract
Wave–particle duality, superposition and entanglement are among the most
counterintuitive features of quantum theory. Their clash with our classical
expectations motivated hidden-variable (HV) theories. With the emergence of quantum
technologies, we can test experimentally the predictions of quantum theory versus HV
theories and put strong restrictions on their key assumptions. Here, we study an
entanglement-assisted version of the quantum delayed-choice experiment and show that
the extension of HV to the controlling devices only exacerbates the contradiction.
We compare HV theories that satisfy the conditions of objectivity (a property of
photons being either particles or waves, but not both), determinism and local
independence of hidden variables with quantum mechanics. Any two of the above
conditions are compatible with it. The conflict becomes manifest when all three
conditions are imposed and persists for any non-zero value of entanglement. We
propose an experiment to test our conclusions. Arguably, the most counterintuitive aspects of quantum mechanics are
indeterminacy of physical quantities and ambiguity of wave/particle behaviour prior to
measurement. Terno et al. propose an experiment to test hidden-variable models
that aim to restore objectivity and determinism in quantum theory.
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Affiliation(s)
- Radu Ionicioiu
- 1] Department of Theoretical Physics, National Institute of Physics and Nuclear Engineering, 077125 Bucharest-Măgurele, Romania [2] Research Center for Spatial Information - CEOSpaceTech, University Politehnica of Bucharest, 313 Splaiul Independentei, 061071 Bucharest, Romania
| | - Thomas Jennewein
- 1] Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 [2] Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - Robert B Mann
- 1] Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 [2] Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 [3] Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2L 2Y6
| | - Daniel R Terno
- Department of Physics and Astronomy, Macquarie University, Sydney, New South Wales 2109, Australia
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37
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Barz S, Kassal I, Ringbauer M, Lipp YO, Dakić B, Aspuru-Guzik A, Walther P. A two-qubit photonic quantum processor and its application to solving systems of linear equations. Sci Rep 2014; 4:6115. [PMID: 25135432 PMCID: PMC4137340 DOI: 10.1038/srep06115] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 07/25/2014] [Indexed: 11/17/2022] Open
Abstract
Large-scale quantum computers will require the ability to apply long sequences of entangling gates to many qubits. In a photonic architecture, where single-qubit gates can be performed easily and precisely, the application of consecutive two-qubit entangling gates has been a significant obstacle. Here, we demonstrate a two-qubit photonic quantum processor that implements two consecutive CNOT gates on the same pair of polarisation-encoded qubits. To demonstrate the flexibility of our system, we implement various instances of the quantum algorithm for solving of systems of linear equations.
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Affiliation(s)
- Stefanie Barz
- 1] Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria [2]
| | - Ivan Kassal
- 1] Department of Chemistry and Chemical Biology, Harvard University, Cambridge MA 02138, United States [2] Centre for Engineered Quantum Systems and Centre for Quantum Computing and Communication Technology, School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia
| | - Martin Ringbauer
- 1] Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria [2]
| | - Yannick Ole Lipp
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Borivoje Dakić
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Alán Aspuru-Guzik
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge MA 02138, United States
| | - Philip Walther
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
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38
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Reducing the impact of intrinsic dissipation in a superconducting circuit by quantum error detection. Nat Commun 2014; 5:3135. [DOI: 10.1038/ncomms4135] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/17/2013] [Indexed: 11/08/2022] Open
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39
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Fisher KAG, Broadbent A, Shalm LK, Yan Z, Lavoie J, Prevedel R, Jennewein T, Resch KJ. Quantum computing on encrypted data. Nat Commun 2014; 5:3074. [DOI: 10.1038/ncomms4074] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 12/06/2013] [Indexed: 11/09/2022] Open
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40
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Mičuda M, Sedlák M, Straka I, Miková M, Dušek M, Ježek M, Fiurášek J. Efficient experimental estimation of fidelity of linear optical quantum Toffoli gate. PHYSICAL REVIEW LETTERS 2013; 111:160407. [PMID: 24182241 DOI: 10.1103/physrevlett.111.160407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Indexed: 06/02/2023]
Abstract
We propose an efficiently measurable lower bound on quantum process fidelity of N-qubit controlled-Z gates. This bound is determined by average output state fidelities for N partially conjugate product bases. A distinct advantage of our approach is that only fidelities with product states need to be measured while keeping the total number of measurements much smaller than what is necessary for full quantum process tomography. As an application, we use this method to experimentally estimate quantum process fidelity F of a three-qubit linear optical quantum Toffoli gate and we find that F≥0.83. We also demonstrate the entangling capability of the gate by preparing Greenberger-Horne-Zeilinger-type three-qubit entangled states from input product states.
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Affiliation(s)
- M Mičuda
- Department of Optics, Palacký University, 17. listopadu 1192/12, CZ-771 46 Olomouc, Czech Republic
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41
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Gazzano O, Almeida MP, Nowak AK, Portalupi SL, Lemaître A, Sagnes I, White AG, Senellart P. Entangling quantum-logic gate operated with an ultrabright semiconductor single-photon source. PHYSICAL REVIEW LETTERS 2013; 110:250501. [PMID: 23829719 DOI: 10.1103/physrevlett.110.250501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Indexed: 06/02/2023]
Abstract
We demonstrate the unambiguous entangling operation of a photonic quantum-logic gate driven by an ultrabright solid-state single-photon source. Indistinguishable single photons emitted by a single semiconductor quantum dot in a micropillar optical cavity are used as target and control qubits. For a source brightness of 0.56 photons per pulse, the measured truth table has an overlap with the ideal case of 68.4±0.5%, increasing to 73.0±1.6% for a source brightness of 0.17 photons per pulse. The gate is entangling: At a source brightness of 0.48, the Bell-state fidelity is above the entangling threshold of 50% and reaches 71.0±3.6% for a source brightness of 0.15.
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Affiliation(s)
- O Gazzano
- Laboratoire de Photonique et de Nanostructures, CNRS, UPR20, Route de Nozay, 91460 Marcoussis, France
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He YM, He Y, Wei YJ, Wu D, Atatüre M, Schneider C, Höfling S, Kamp M, Lu CY, Pan JW. On-demand semiconductor single-photon source with near-unity indistinguishability. NATURE NANOTECHNOLOGY 2013; 8:213-217. [PMID: 23377455 DOI: 10.1038/nnano.2012.262] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 12/13/2012] [Indexed: 06/01/2023]
Abstract
Single-photon sources based on semiconductor quantum dots offer distinct advantages for quantum information, including a scalable solid-state platform, ultrabrightness and interconnectivity with matter qubits. A key prerequisite for their use in optical quantum computing and solid-state networks is a high level of efficiency and indistinguishability. Pulsed resonance fluorescence has been anticipated as the optimum condition for the deterministic generation of high-quality photons with vanishing effects of dephasing. Here, we generate pulsed single photons on demand from a single, microcavity-embedded quantum dot under s-shell excitation with 3 ps laser pulses. The π pulse-excited resonance-fluorescence photons have less than 0.3% background contribution and a vanishing two-photon emission probability. Non-postselective Hong-Ou-Mandel interference between two successively emitted photons is observed with a visibility of 0.97(2), comparable to trapped atoms and ions. Two single photons are further used to implement a high-fidelity quantum controlled-NOT gate.
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Affiliation(s)
- Yu-Ming He
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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Xu X, Xie Z, Zheng J, Liang J, Zhong T, Yu M, Kocaman S, Lo GQ, Kwong DL, Englund DR, Wong FNC, Wong CW. Near-infrared Hong-Ou-Mandel interference on a silicon quantum photonic chip. OPTICS EXPRESS 2013; 21:5014-5024. [PMID: 23482034 DOI: 10.1364/oe.21.005014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Near-infrared Hong-Ou-Mandel quantum interference is observed in silicon nanophotonic directional couplers with raw visibilities on-chip at 90.5%. Spectrally-bright 1557-nm two-photon states are generated in a periodically-poled KTiOPO₄ waveguide chip, serving as the entangled photon source and pumped with a self-injection locked laser, for the photon statistical measurements. Efficient four-port coupling in the communications C-band and in the high-index-contrast silicon photonics platform is demonstrated, with matching theoretical predictions of the quantum interference visibility. Constituents for the residual quantum visibility imperfection are examined, supported with theoretical analysis of the sequentially-triggered multipair biphoton, towards scalable high-bitrate quantum information processing and communications. The on-chip HOM interference is useful towards scalable high-bitrate quantum information processing and communications.
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Affiliation(s)
- Xinan Xu
- Optical Nanostructures Laboratory, Center for Integrated Science and Engineering, Solid-State Science and Engineering, and Mechanical Engineering, Columbia University, New York, New York 10027, USA
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Abstract
In the 1940s, the first generation of modern computers used vacuum tube oscillators as their principle components, however, with the development of the transistor, such oscillator based computers quickly became obsolete. As the demand for faster and lower power computers continues, transistors are themselves approaching their theoretical limit and emerging technologies must eventually supersede them. With the development of optical oscillators and Josephson junction technology, we are again presented with the possibility of using oscillators as the basic components of computers, and it is possible that the next generation of computers will be composed almost entirely of oscillatory devices. Here, we demonstrate how coupled threshold oscillators may be used to perform binary logic in a manner entirely consistent with modern computer architectures. We describe a variety of computational circuitry and demonstrate working oscillator models of both computation and memory.
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Affiliation(s)
- Jon Borresen
- School of Computing, Mathematics and Digital Technology, Manchester Metropolitan University, Manchester, United Kingdom.
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Tanida M, Okamoto R, Takeuchi S. Highly indistinguishable heralded single-photon sources using parametric down conversion. OPTICS EXPRESS 2012; 20:15275-15285. [PMID: 22772225 DOI: 10.1364/oe.20.015275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We theoretically and experimentally investigate the conditions necessary to realize highly indistinguishable single-photon sources using parametric down conversion. The visibilities of Hong-Ou-Mandel (HOM) interference between photons in different fluorescence pairs were measured and a visibility of 95.8 ± 2% was observed using a 0.7-mm-long beta barium borate crystal and 2-nm bandpass filters, after compensating for the reflectivity of the beam splitter. A theoretical model of HOM interference visibilities is proposed that considers non-uniform down conversion process inside the nonlinear crystal. It well explains the experimental results.
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Affiliation(s)
- Masato Tanida
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki 567-0047, Japan
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El Sherif MH, Ahmed OS, Bakr MH, Swillam MA. Polarization-controlled excitation of multilevel plasmonic nano-circuits using single silicon nanowire. OPTICS EXPRESS 2012; 20:12473-12486. [PMID: 22714235 DOI: 10.1364/oe.20.012473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We propose a surface plasmon polarization-controlled beam splitter based on plasmonic slot waveguides (PSWs). It couples light of different polarizations from a silicon nanowire into multilevel plasmonic networks. Two orthogonal PSWs are utilized as the guiding waveguides for each polarization. The proposed structure overcomes inherent polarization limitation in plasmonic structures by providing multilevel optical signal processing. This ability of controlling polarization can be exploited to achieve 3-D multilevel plasmonic circuits and polarization controlled chip to chip channel. Our device is of a compact size and a wide band operation. The device utilizes both quasi-TE and quasi-TM polarizations to allow for increased optical processing capability. The crosstalk is minimal between the two polarizations propagating in two different levels. We achieve good transmission efficiency at a wavelength of 1.55 µm for different polarizations. We analyze and simulate the structure using the FDTD method. The proposed device can be utilized in integrated chips for optical signal processing and optical computations.
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Affiliation(s)
- Mohamed H El Sherif
- Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
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Integrated photonic quantum gates for polarization qubits. Nat Commun 2011; 2:566. [PMID: 22127062 PMCID: PMC3482629 DOI: 10.1038/ncomms1570] [Citation(s) in RCA: 227] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 10/26/2011] [Indexed: 11/24/2022] Open
Abstract
The ability to manipulate quantum states of light by integrated devices may open new perspectives both for fundamental tests of quantum mechanics and for novel technological applications. However, the technology for handling polarization-encoded qubits, the most commonly adopted approach, is still missing in quantum optical circuits. Here we demonstrate the first integrated photonic controlled-NOT (CNOT) gate for polarization-encoded qubits. This result has been enabled by the integration, based on femtosecond laser waveguide writing, of partially polarizing beam splitters on a glass chip. We characterize the logical truth table of the quantum gate demonstrating its high fidelity to the expected one. In addition, we show the ability of this gate to transform separable states into entangled ones and vice versa. Finally, the full accessibility of our device is exploited to carry out a complete characterization of the CNOT gate through a quantum process tomography. As quantum information processing continues to develop apace, the need for integrated photonic devices becomes ever greater for both fundamental measurements and technological applications. To this end, Crespi et al. demonstrate a high-fidelity photonic controlled-NOT gate on a glass chip.
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Ma XS, Zotter S, Tetik N, Qarry A, Jennewein T, Zeilinger A. A high-speed tunable beam splitter for feed-forward photonic quantum information processing. OPTICS EXPRESS 2011; 19:22723-22730. [PMID: 22109153 DOI: 10.1364/oe.19.022723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We realize quantum gates for path qubits with a high-speed, polarization-independent and tunable beam splitter. Two electro-optical modulators act in a Mach-Zehnder interferometer as high-speed phase shifters and rapidly tune its splitting ratio. We test its performance with heralded single photons, observing a polarization-independent interference contrast above 95%. The switching time is about 5.6 ns, and a maximal repetition rate is 2.5 MHz. We demonstrate tunable feed-forward operations of a single-qubit gate of path-encoded qubits and a two-qubit gate via measurement-induced interaction between two photons.
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Affiliation(s)
- Xiao-Song Ma
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria.
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Zou CL, Sun FW, Dong CH, Ren XF, Cui JM, Chen XD, Han ZF, Guo GC. Broadband integrated polarization beam splitter with surface plasmon. OPTICS LETTERS 2011; 36:3630-3632. [PMID: 21931414 DOI: 10.1364/ol.36.003630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A broadband integrated waveguide polarization beam splitter consisting of a metal nanoribbon and two dielectric waveguides is proposed and numerically investigated. This surface plasmon based device provides a unique approach for polarization sensitive manipulation of light in an integrated circuit and will be essential for future classical and quantum information processes.
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Affiliation(s)
- C-L Zou
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui, China
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Realization of a Knill-Laflamme-Milburn controlled-NOT photonic quantum circuit combining effective optical nonlinearities. Proc Natl Acad Sci U S A 2011; 108:10067-71. [PMID: 21646543 DOI: 10.1073/pnas.1018839108] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quantum information science addresses how uniquely quantum mechanical phenomena such as superposition and entanglement can enhance communication, information processing, and precision measurement. Photons are appealing for their low-noise, light-speed transmission and ease of manipulation using conventional optical components. However, the lack of highly efficient optical Kerr nonlinearities at the single photon level was a major obstacle. In a breakthrough, Knill, Laflamme, and Milburn (KLM) showed that such an efficient nonlinearity can be achieved using only linear optical elements, auxiliary photons, and measurement [Knill E, Laflamme R, Milburn GJ (2001) Nature 409:46-52]. KLM proposed a heralded controlled-NOT (CNOT) gate for scalable quantum computation using a photonic quantum circuit to combine two such nonlinear elements. Here we experimentally demonstrate a KLM CNOT gate. We developed a stable architecture to realize the required four-photon network of nested multiple interferometers based on a displaced-Sagnac interferometer and several partially polarizing beamsplitters. This result confirms the first step in the original KLM "recipe" for all-optical quantum computation, and should be useful for on-demand entanglement generation and purification. Optical quantum circuits combining giant optical nonlinearities may find wide applications in quantum information processing, communication, and sensing.
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