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Knaut CM, Suleymanzade A, Wei YC, Assumpcao DR, Stas PJ, Huan YQ, Machielse B, Knall EN, Sutula M, Baranes G, Sinclair N, De-Eknamkul C, Levonian DS, Bhaskar MK, Park H, Lončar M, Lukin MD. Entanglement of nanophotonic quantum memory nodes in a telecom network. Nature 2024; 629:573-578. [PMID: 38750231 PMCID: PMC11096112 DOI: 10.1038/s41586-024-07252-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 02/28/2024] [Indexed: 05/18/2024]
Abstract
A key challenge in realizing practical quantum networks for long-distance quantum communication involves robust entanglement between quantum memory nodes connected by fibre optical infrastructure1-3. Here we demonstrate a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centres in nanophotonic diamond cavities integrated with a telecommunication fibre network. Remote entanglement is generated by the cavity-enhanced interactions between the electron spin qubits of the SiVs and optical photons. Serial, heralded spin-photon entangling gate operations with time-bin qubits are used for robust entanglement of separated nodes. Long-lived nuclear spin qubits are used to provide second-long entanglement storage and integrated error detection. By integrating efficient bidirectional quantum frequency conversion of photonic communication qubits to telecommunication frequencies (1,350 nm), we demonstrate the entanglement of two nuclear spin memories through 40 km spools of low-loss fibre and a 35-km long fibre loop deployed in the Boston area urban environment, representing an enabling step towards practical quantum repeaters and large-scale quantum networks.
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Affiliation(s)
- C M Knaut
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - A Suleymanzade
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Y-C Wei
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - D R Assumpcao
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - P-J Stas
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Y Q Huan
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - B Machielse
- Department of Physics, Harvard University, Cambridge, MA, USA
- AWS Center for Quantum Networking, Boston, MA, USA
| | - E N Knall
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - M Sutula
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - G Baranes
- Department of Physics, Harvard University, Cambridge, MA, USA
- Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - N Sinclair
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | | | - D S Levonian
- Department of Physics, Harvard University, Cambridge, MA, USA
- AWS Center for Quantum Networking, Boston, MA, USA
| | - M K Bhaskar
- Department of Physics, Harvard University, Cambridge, MA, USA
- AWS Center for Quantum Networking, Boston, MA, USA
| | - H Park
- Department of Physics, Harvard University, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - M Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - M D Lukin
- Department of Physics, Harvard University, Cambridge, MA, USA.
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Stas PJ, Huan YQ, Machielse B, Knall EN, Suleymanzade A, Pingault B, Sutula M, Ding SW, Knaut CM, Assumpcao DR, Wei YC, Bhaskar MK, Riedinger R, Sukachev DD, Park H, Lončar M, Levonian DS, Lukin MD. Robust multi-qubit quantum network node with integrated error detection. Science 2022; 378:557-560. [DOI: 10.1126/science.add9771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Long-distance quantum communication and networking require quantum memory nodes with efficient optical interfaces and long memory times. We report the realization of an integrated two-qubit network node based on silicon-vacancy centers (SiVs) in diamond nanophotonic cavities. Our qubit register consists of the SiV electron spin acting as a communication qubit and the strongly coupled silicon-29 nuclear spin acting as a memory qubit with a quantum memory time exceeding 2 seconds. By using a highly strained SiV, we realize electron-photon entangling gates at temperatures up to 1.5 kelvin and nucleus-photon entangling gates up to 4.3 kelvin. We also demonstrate efficient error detection in nuclear spin–photon gates by using the electron spin as a flag qubit, making this platform a promising candidate for scalable quantum repeaters.
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Affiliation(s)
- P.-J. Stas
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Y. Q. Huan
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - B. Machielse
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- AWS Center for Quantum Networking, Boston, MA 02210, USA
| | - E. N. Knall
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - A. Suleymanzade
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - B. Pingault
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- QuTech, Delft University of Technology, 2600 GA Delft, Netherlands
- Kavli Institute of Nanoscience Delft, Delft University of Technology, 2600 GA Delft, Netherlands
| | - M. Sutula
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - S. W. Ding
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - C. M. Knaut
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - D. R. Assumpcao
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Y.-C. Wei
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - M. K. Bhaskar
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- AWS Center for Quantum Networking, Boston, MA 02210, USA
| | - R. Riedinger
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Institut für Laserphysik und Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany
| | - D. D. Sukachev
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- AWS Center for Quantum Networking, Boston, MA 02210, USA
| | - H. Park
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - M. Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - D. S. Levonian
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- AWS Center for Quantum Networking, Boston, MA 02210, USA
| | - M. D. Lukin
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
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3
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Levonian DS, Riedinger R, Machielse B, Knall EN, Bhaskar MK, Knaut CM, Bekenstein R, Park H, Lončar M, Lukin MD. Optical Entanglement of Distinguishable Quantum Emitters. Phys Rev Lett 2022; 128:213602. [PMID: 35687460 DOI: 10.1103/physrevlett.128.213602] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 03/21/2022] [Indexed: 06/15/2023]
Abstract
Solid-state quantum emitters are promising candidates for the realization of quantum networks, owing to their long-lived spin memories, high-fidelity local operations, and optical connectivity for long-range entanglement. However, due to differences in local environment, solid-state emitters typically feature a range of distinct transition frequencies, which makes it challenging to create optically mediated entanglement between arbitrary emitter pairs. We propose and demonstrate an efficient method for entangling emitters with optical transitions separated by many linewidths. In our approach, electro-optic modulators enable a single photon to herald a parity measurement on a pair of spin qubits. We experimentally demonstrate the protocol using two silicon-vacancy centers in a diamond nanophotonic cavity, with optical transitions separated by 7.4 GHz. Working with distinguishable emitters allows for individual qubit addressing and readout, enabling parallel control and entanglement of both colocated and spatially separated emitters, a key step toward scaling up quantum information processing systems.
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Affiliation(s)
- D S Levonian
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- AWS Center for Quantum Computing, Pasadena, California 91125, USA
| | - R Riedinger
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Institut für Laserphysik und Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany
| | - B Machielse
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- AWS Center for Quantum Computing, Pasadena, California 91125, USA
| | - E N Knall
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - M K Bhaskar
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- AWS Center for Quantum Computing, Pasadena, California 91125, USA
| | - C M Knaut
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - R Bekenstein
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - H Park
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - M Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - M D Lukin
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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4
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Bhaskar MK, Riedinger R, Machielse B, Levonian DS, Nguyen CT, Knall EN, Park H, Englund D, Lončar M, Sukachev DD, Lukin MD. Experimental demonstration of memory-enhanced quantum communication. Nature 2020; 580:60-64. [PMID: 32238931 DOI: 10.1038/s41586-020-2103-5] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 01/16/2020] [Indexed: 11/09/2022]
Abstract
The ability to communicate quantum information over long distances is of central importance in quantum science and engineering1. Although some applications of quantum communication such as secure quantum key distribution2,3 are already being successfully deployed4-7, their range is currently limited by photon losses and cannot be extended using straightforward measure-and-repeat strategies without compromising unconditional security8. Alternatively, quantum repeaters9, which utilize intermediate quantum memory nodes and error correction techniques, can extend the range of quantum channels. However, their implementation remains an outstanding challenge10-16, requiring a combination of efficient and high-fidelity quantum memories, gate operations, and measurements. Here we use a single solid-state spin memory integrated in a nanophotonic diamond resonator17-19 to implement asynchronous photonic Bell-state measurements, which are a key component of quantum repeaters. In a proof-of-principle experiment, we demonstrate high-fidelity operation that effectively enables quantum communication at a rate that surpasses the ideal loss-equivalent direct-transmission method while operating at megahertz clock speeds. These results represent a crucial step towards practical quantum repeaters and large-scale quantum networks20,21.
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Affiliation(s)
- M K Bhaskar
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - R Riedinger
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - B Machielse
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - D S Levonian
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - C T Nguyen
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - E N Knall
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - H Park
- Department of Physics, Harvard University, Cambridge, MA, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - D Englund
- Research Laboratory of Electronics, MIT, Cambridge, MA, USA
| | - M Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - D D Sukachev
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - M D Lukin
- Department of Physics, Harvard University, Cambridge, MA, USA.
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5
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Nguyen CT, Sukachev DD, Bhaskar MK, Machielse B, Levonian DS, Knall EN, Stroganov P, Riedinger R, Park H, Lončar M, Lukin MD. Quantum Network Nodes Based on Diamond Qubits with an Efficient Nanophotonic Interface. Phys Rev Lett 2019; 123:183602. [PMID: 31763904 DOI: 10.1103/physrevlett.123.183602] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/16/2019] [Indexed: 06/10/2023]
Abstract
Quantum networks require functional nodes consisting of stationary registers with the capability of high-fidelity quantum processing and storage, which efficiently interface with photons propagating in an optical fiber. We report a significant step towards realization of such nodes using a diamond nanocavity with an embedded silicon-vacancy (SiV) color center and a proximal nuclear spin. Specifically, we show that efficient SiV-cavity coupling (with cooperativity C>30) provides a nearly deterministic interface between photons and the electron spin memory, featuring coherence times exceeding 1 ms. Employing coherent microwave control, we demonstrate heralded single photon storage in the long-lived spin memory as well as a universal control over a cavity-coupled two-qubit register consisting of a SiV and a proximal ^{13}C nuclear spin with nearly second-long coherence time, laying the groundwork for implementing quantum repeaters.
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Affiliation(s)
- C T Nguyen
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - D D Sukachev
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - M K Bhaskar
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - B Machielse
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - D S Levonian
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - E N Knall
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - P Stroganov
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - R Riedinger
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - H Park
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - M Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - M D Lukin
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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