1
|
Liang S, Cheng J, Qin J, Li J, Shi Y, Yan Z, Jia X, Xie C, Peng K. High-Speed Quantum Radio-Frequency-Over-Light Communication. PHYSICAL REVIEW LETTERS 2024; 132:140802. [PMID: 38640392 DOI: 10.1103/physrevlett.132.140802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 03/12/2024] [Indexed: 04/21/2024]
Abstract
Quantum dense coding (QDC) means to transmit two classical bits by only transferring one quantum bit, which has enabled high-capacity information transmission and strengthened system security. Continuous-variable QDC offers a promising solution to increase communication rates while achieving seamless integration with classical communication systems. Here, we propose and experimentally demonstrate a high-speed quantum radio-frequency-over-light (RFOL) communication scheme based on QDC with an entangled state, and achieve a practical rate of 20 Mbps through digital modulation and RFOL communication. This scheme bridges the gap between quantum technology and real-world communication systems, which bring QDC closer to practical applications and offer prospects for further enhancement of metropolitan communication networks.
Collapse
Affiliation(s)
- Shaocong Liang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Jialin Cheng
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Jiliang Qin
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Jiatong Li
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Yi Shi
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Zhihui Yan
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Xiaojun Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Changde Xie
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Kunchi Peng
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China
| |
Collapse
|
2
|
Piveteau A, Pauwels J, Håkansson E, Muhammad S, Bourennane M, Tavakoli A. Entanglement-assisted quantum communication with simple measurements. Nat Commun 2022; 13:7878. [PMID: 36550100 PMCID: PMC9780301 DOI: 10.1038/s41467-022-33922-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 10/07/2022] [Indexed: 12/24/2022] Open
Abstract
Dense coding is the seminal example of how entanglement can boost qubit communication, from sending one bit to sending two bits. This is made possible by projecting separate particles onto a maximally entangled basis. We investigate more general communication tasks, in both theory and experiment, and show that simpler measurements enable strong and sometimes even optimal entanglement-assisted qubit communication protocols. Using only partial Bell state analysers for two qubits, we demonstrate quantum correlations that cannot be simulated with two bits of classical communication. Then, we show that there exists an established and operationally meaningful task for which product measurements are sufficient for the strongest possible quantum predictions based on a maximally entangled two-qubit state. Our results reveal that there are scenarios in which the power of entanglement in enhancing quantum communication can be harvested in simple and scalable optical experiments.
Collapse
Affiliation(s)
- Amélie Piveteau
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - Jef Pauwels
- grid.4989.c0000 0001 2348 0746Laboratoire d’Information Quantique, CP 225, Université libre de Bruxelles (ULB), Av. F. D. Roosevelt 50, 1050 Bruxelles, Belgium
| | - Emil Håkansson
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, S-10691 Stockholm, Sweden ,Hitachi Energy Research, Forskargränd 7, 72219 Västerås, Sweden
| | - Sadiq Muhammad
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - Mohamed Bourennane
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - Armin Tavakoli
- grid.4299.60000 0001 2169 3852Institute for Quantum Optics and Quantum Information - IQOQI Vienna, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria ,grid.5329.d0000 0001 2348 4034Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Vienna, Austria
| |
Collapse
|
3
|
Hao S, Shi H, Li W, Shapiro JH, Zhuang Q, Zhang Z. Entanglement-Assisted Communication Surpassing the Ultimate Classical Capacity. PHYSICAL REVIEW LETTERS 2021; 126:250501. [PMID: 34241503 DOI: 10.1103/physrevlett.126.250501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 05/17/2021] [Indexed: 06/13/2023]
Abstract
Entanglement underpins a variety of quantum-enhanced communication, sensing, and computing capabilities. Entanglement-assisted communication (EACOMM) leverages entanglement preshared by communicating parties to boost the rate of classical information transmission. Pioneering theory works showed that EACOMM can enable a communication rate well beyond the ultimate classical capacity of optical communications, but an experimental demonstration of any EACOMM advantage remains elusive. In this Letter we report the implementation of EACOMM surpassing the classical capacity over lossy and noisy bosonic channels. We construct a high-efficiency entanglement source and a phase-conjugate quantum receiver to reap the benefit of preshared entanglement, despite entanglement being broken by channel loss and noise. We show that EACOMM beats the Holevo-Schumacher-Westmoreland capacity of classical communication by up to 16.3%, when both protocols are subject to the same power constraint at the transmitter. As a practical performance benchmark, we implement a classical communication protocol with the identical characteristics for the encoded signal, showing that EACOMM can reduce the bit-error rate by up to 69% over the same bosonic channel. Our work opens a route to provable quantum advantages in a wide range of quantum information processing tasks.
Collapse
Affiliation(s)
- Shuhong Hao
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, USA
| | - Haowei Shi
- James C. Wyant College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
| | - Wei Li
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, USA
| | - Jeffrey H Shapiro
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Quntao Zhuang
- James C. Wyant College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
- Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA
| | - Zheshen Zhang
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, USA
- James C. Wyant College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
- Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA
| |
Collapse
|
4
|
Ding L, Mardazad S, Das S, Szalay S, Schollwöck U, Zimborás Z, Schilling C. Concept of Orbital Entanglement and Correlation in Quantum Chemistry. J Chem Theory Comput 2021; 17:79-95. [PMID: 33430597 DOI: 10.1021/acs.jctc.0c00559] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A recent development in quantum chemistry has established the quantum mutual information between orbitals as a major descriptor of electronic structure. This has already facilitated remarkable improvements in numerical methods and may lead to a more comprehensive foundation for chemical bonding theory. Building on this promising development, our work provides a refined discussion of quantum information theoretical concepts by introducing the physical correlation and its separation into classical and quantum parts as distinctive quantifiers of electronic structure. In particular, we succeed in quantifying the entanglement. Intriguingly, our results for different molecules reveal that the total correlation between orbitals is mainly classical, raising questions about the general significance of entanglement in chemical bonding. Our work also shows that implementing the fundamental particle number superselection rule, so far not accounted for in quantum chemistry, removes a major part of correlation and entanglement seen previously. In that respect, realizing quantum information processing tasks with molecular systems might be more challenging than anticipated.
Collapse
Affiliation(s)
- Lexin Ding
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany.,Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
| | - Sam Mardazad
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany.,Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
| | - Sreetama Das
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany.,Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
| | - Szilárd Szalay
- Strongly Correlated Systems Lendület Research Group, Wigner Research Centre for Physics, 29-33, Konkoly-Thege Miklós Street, H-1121 Budapest, Hungary
| | - Ulrich Schollwöck
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany.,Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
| | - Zoltán Zimborás
- Theoretical Physics Department, Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary.,MTA-BME Lendület Quantum Information Theory Research Group, H-1111 Budapest, Hungary.,Mathematical Institute, Budapest University of Technology and Economics, P.O. Box 91, H-1111 Budapest, Hungary
| | - Christian Schilling
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany.,Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany.,Wolfson College, University of Oxford, Linton Road, Oxford OX2 6UD, United Kingdom
| |
Collapse
|
5
|
Yang ZB, Liu JS, Jin H, Zhu QH, Zhu AD, Liu HY, Ming Y, Yang RC. Entanglement enhanced by Kerr nonlinearity in a cavity-optomagnonics system. OPTICS EXPRESS 2020; 28:31862-31871. [PMID: 33115150 DOI: 10.1364/oe.404522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 09/29/2020] [Indexed: 06/11/2023]
Abstract
We present a method to enhance steady-state bipartite and tripartite entanglement in a cavity-optomagnonics system by utilizing the Kerr nonlinearity originating from the magnetocrystalline anisotropy. The system comprises two microwave cavities and a magnon and represents the collective motion of several spins in a macroscopic ferrimagnet. We prove that Kerr nonlinearity is reliable for the enhancement of entanglement and produces a small frequency shift in the optimal detuning. Our system is more robust against the environment-induced decoherence than traditional optomechanical systems. Finally, we briefly analyze the validity of the system and demonstrate its feasibility for detecting the generated entanglement.
Collapse
|
6
|
Ding L, Schilling C. Correlation Paradox of the Dissociation Limit: A Quantum Information Perspective. J Chem Theory Comput 2020; 16:4159-4175. [PMID: 32433873 DOI: 10.1021/acs.jctc.0c00054] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interplay between electron interaction and geometry in a molecular system can lead to rather paradoxical situations. The prime example is the dissociation limit of the hydrogen molecule. While a significant increase of the distance r between the two nuclei marginalizes the electron-electron interaction, the exact ground state does, however, not take the form of a single Slater determinant. By first reviewing and then employing concepts from quantum information theory, we resolve this paradox and its generalizations to more complex systems in a quantitative way. To be more specific, we illustrate and prove that thermal noise due to finite, possibly even just infinitesimally low, temperature T will destroy the entanglement beyond a critical separation distance rcrit(T) entirely. Our analysis is comprehensive in the sense that we simultaneously discuss both total correlation and entanglement in the particle picture as well as in the orbital/mode picture. Our results reveal a conceptually new characterization of static and dynamical correlation in ground states by relating them to the (non)robustness of correlation with respect to thermal noise.
Collapse
Affiliation(s)
- Lexin Ding
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany
| | - Christian Schilling
- Faculty of Physics, Arnold Sommerfeld Centre for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München, Germany.,Wolfson College, University of Oxford, Linton Rd., Oxford OX2 6UD, United Kingdom
| |
Collapse
|
7
|
Hu XM, Guo Y, Liu BH, Huang YF, Li CF, Guo GC. Beating the channel capacity limit for superdense coding with entangled ququarts. SCIENCE ADVANCES 2018; 4:eaat9304. [PMID: 30035231 PMCID: PMC6054506 DOI: 10.1126/sciadv.aat9304] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/05/2018] [Indexed: 05/02/2023]
Abstract
Quantum superdense coding protocols enhance channel capacity by using shared quantum entanglement between two users. The channel capacity can be as high as 2 when one uses entangled qubits. However, this limit can be surpassed by using high-dimensional entanglement. We report an experiment that exceeds the limit using high-quality entangled ququarts with fidelities up to 0.98, demonstrating a channel capacity of 2.09 ± 0.01. The measured channel capacity is also higher than that obtained when transmitting only one ququart. We use the setup to transmit a five-color image with a fidelity of 0.952. Our experiment shows the great advantage of high-dimensional entanglement and will stimulate research on high-dimensional quantum information processes.
Collapse
Affiliation(s)
- Xiao-Min Hu
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Yu Guo
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Bi-Heng Liu
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Corresponding author. (B.-H.L.); (C.-F.L.)
| | - Yun-Feng Huang
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| | - Chuan-Feng Li
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Corresponding author. (B.-H.L.); (C.-F.L.)
| | - Guang-Can Guo
- Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
| |
Collapse
|
8
|
Heaney L, Vedral V. Natural mode entanglement as a resource for quantum communication. PHYSICAL REVIEW LETTERS 2009; 103:200502. [PMID: 20365969 DOI: 10.1103/physrevlett.103.200502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Indexed: 05/29/2023]
Abstract
Natural particle-number entanglement resides between spatial modes in coherent ultracold atomic gases. However, operations on the modes are restricted by a superselection rule that forbids coherent superpositions of different particle numbers. This seemingly prevents mode entanglement being used as a resource for quantum communication. In this Letter, we demonstrate that mode entanglement of a single massive particle can be used for dense coding and quantum teleportation despite the superselection rule. In particular, we provide schemes where the dense coding linear photonic channel capacity is reached without a shared reservoir and where the full quantum channel capacity is achieved if both parties share a coherent particle reservoir.
Collapse
Affiliation(s)
- Libby Heaney
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom.
| | | |
Collapse
|
9
|
Xue P, Sanders BC, Leibfried D. Quantum walk on a line for a trapped ion. PHYSICAL REVIEW LETTERS 2009; 103:183602. [PMID: 19905805 DOI: 10.1103/physrevlett.103.183602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Indexed: 05/28/2023]
Abstract
We show that a multistep quantum walk can be realized for a single trapped ion with an interpolation between a quantum and random walk achieved by randomizing the generalized Hadamard coin flip phase. The signature of the quantum walk is manifested not only in the ion's position but also in its phonon number, which makes an ion-trap implementation of the quantum walk feasible.
Collapse
Affiliation(s)
- Peng Xue
- Department of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | | | | |
Collapse
|
10
|
|
11
|
|
12
|
Langford NK, Weinhold TJ, Prevedel R, Resch KJ, Gilchrist A, O'Brien JL, Pryde GJ, White AG. Demonstration of a simple entangling optical gate and its use in bell-state analysis. PHYSICAL REVIEW LETTERS 2005; 95:210504. [PMID: 16384124 DOI: 10.1103/physrevlett.95.210504] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Indexed: 05/05/2023]
Abstract
We demonstrate a new architecture for an optical entangling gate that is significantly simpler than previous realizations, using partially polarizing beam splitters so that only a single optical mode-matching condition is required. We demonstrate operation of a controlled-z gate in both continuous-wave and pulsed regimes of operation, fully characterizing it in each case using quantum process tomography. We also demonstrate a fully resolving, nondeterministic optical Bell-state analyzer based on this controlled-z gate. This new architecture is ideally suited to guided optics implementations of optical gates.
Collapse
Affiliation(s)
- N K Langford
- Centre for Quantum Computer Technology, University of Queensland, Brisbane QLD 4072, Australia
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Chiaverini J, Britton J, Leibfried D, Knill E, Barrett MD, Blakestad RB, Itano WM, Jost JD, Langer C, Ozeri R, Schaetz T, Wineland DJ. Implementation of the Semiclassical Quantum Fourier Transform in a Scalable System. Science 2005; 308:997-1000. [PMID: 15890877 DOI: 10.1126/science.1110335] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report the implementation of the semiclassical quantum Fourier transform in a system of three beryllium ion qubits (two-level quantum systems) confined in a segmented multizone trap. The quantum Fourier transform is the crucial final step in Shor's algorithm, and it acts on a register of qubits to determine the periodicity of the quantum state's amplitudes. Because only probability amplitudes are required for this task, a more efficient semiclassical version can be used, for which only single-qubit operations conditioned on measurement outcomes are required. We apply the transform to several input states of different periodicities; the results enable the location of peaks corresponding to the original periods. This demonstration incorporates the key elements of a scalable ion-trap architecture, suggesting the future capability of applying the quantum Fourier transform to a large number of qubits as required for a useful quantum factoring algorithm.
Collapse
Affiliation(s)
- J Chiaverini
- National Institute of Standards and Technology, Boulder, CO 80305, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Schaetz T, Barrett MD, Leibfried D, Britton J, Chiaverini J, Itano WM, Jost JD, Knill E, Langer C, Wineland DJ. Enhanced quantum state detection efficiency through quantum information processing. PHYSICAL REVIEW LETTERS 2005; 94:010501. [PMID: 15698054 DOI: 10.1103/physrevlett.94.010501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2004] [Indexed: 05/24/2023]
Abstract
We investigate theoretically and experimentally how quantum state-detection efficiency is improved by the use of quantum information processing (QIP). Experimentally, we encode the state of one 9Be(+) ion qubit with one additional ancilla qubit. By measuring both qubits, we reduce the state-detection error in the presence of noise. The deviation from the theoretically allowed reduction is due to infidelities of the QIP operations. Applying this general scheme to more ancilla qubits suggests that error in the individual qubit measurements need not be a limit to scalable quantum computation.
Collapse
Affiliation(s)
- T Schaetz
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Chiaverini J, Leibfried D, Schaetz T, Barrett MD, Blakestad RB, Britton J, Itano WM, Jost JD, Knill E, Langer C, Ozeri R, Wineland DJ. Realization of quantum error correction. Nature 2005; 432:602-5. [PMID: 15577904 DOI: 10.1038/nature03074] [Citation(s) in RCA: 321] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Accepted: 10/01/2004] [Indexed: 11/08/2022]
Abstract
Scalable quantum computation and communication require error control to protect quantum information against unavoidable noise. Quantum error correction protects information stored in two-level quantum systems (qubits) by rectifying errors with operations conditioned on the measurement outcomes. Error-correction protocols have been implemented in nuclear magnetic resonance experiments, but the inherent limitations of this technique prevent its application to quantum information processing. Here we experimentally demonstrate quantum error correction using three beryllium atomic-ion qubits confined to a linear, multi-zone trap. An encoded one-qubit state is protected against spin-flip errors by means of a three-qubit quantum error-correcting code. A primary ion qubit is prepared in an initial state, which is then encoded into an entangled state of three physical qubits (the primary and two ancilla qubits). Errors are induced simultaneously in all qubits at various rates. The encoded state is decoded back to the primary ion one-qubit state, making error information available on the ancilla ions, which are separated from the primary ion and measured. Finally, the primary qubit state is corrected on the basis of the ancillae measurement outcome. We verify error correction by comparing the corrected final state to the uncorrected state and to the initial state. In principle, the approach enables a quantum state to be maintained by means of repeated error correction, an important step towards scalable fault-tolerant quantum computation using trapped ions.
Collapse
Affiliation(s)
- J Chiaverini
- Time and Frequency Division, Mathematical and Computational Sciences Division, NIST, Boulder, Colorado 80305, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|