Robust multi-qubit quantum network node with integrated error detection
Pieter-Jan Stas, Yan Qi Huan, Bartholomeus Machielse, Erik Knall, Aziza Suleymanzade, Benjamin Pingault, Madison Sutula, Sophie Weiyi Ding, Can M. Knaut, Daniel Assumpção, Yan-Cheng Wei, Mihir K. Bhaskar, Ralf Riedinger, Denis D. Sukachev, Hongkun Park, Marko Lončar, David Levonian, Mikhail D. Lukin
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.