Robust multi-qubit quantum network node with integrated error detection

• Published in: arXiv.org
• Main Authors: Pieter-Jan Stas, Yan Qi Huan, Bartholomeus Machielse, Knall, Erik N, Suleymanzade, Aziza, Pingault, Benjamin, Sutula, Madison, Ding, Sophie W, Knaut, Can M, Assumpcao, Daniel R, Yan-Cheng, Wei, Bhaskar, Mihir K, Riedinger, Ralf, Sukachev, Denis D, Park, Hongkun, Lončar, Marko, Levonian, David S, Lukin, Mikhail D
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 26.07.2022
• Subjects: Diamonds; Electron spin; Error detection; Gates; High temperature; Nuclear spin; Optical memory (data storage); Photons; Physics - Quantum Physics; Quantum phenomena; Qubits (quantum computing); Repeaters
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2207.13128

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 29Si nuclear spin acting as a memory qubit with a quantum memory time exceeding two seconds. By using a highly strained SiV with suppressed electron spin-phonon interactions, we realize electron-photon entangling gates at elevated temperatures up to 1.5 K and nucleus-photon entangling gates up to 4.3 K. Finally, we 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.