Controlling spin-photon interfaces and nuclear spin registers in color centers

Alexey V. Akimov

Cathryn P. Michaels, Jesús Arjona Martínez, Romain Debroux +6 more

Felipe Ortiz Huerta

Isaac Harris, Cathryn P. Michaels, Kevin C. Chen +16 more

A quantum register coupled to a spin-photon interface is a key component in quantum communication and information processing.Group-IV color centers in diamond (SiV -, GeV -, and SnV -) are promising candidates for this application, comprising an electronic spin with optical transitions coupled to a nuclear spin as the quantum register.However, the creation of a quantum register for these color centers with deterministic and strong coupling to the spin-photon interface remains challenging.Here, we make first-principles predictions of the hyperfine parameters of the group-IV color centers, which we verify experimentally with a comprehensive comparison between the spectra of spin active and spin neutral intrinsic dopant nuclei in single GeV -and SnV -emitters.In line with the theoretical predictions, detailed spectroscopy on large sample sizes reveals that hyperfine coupling causes a splitting of the optical transition of SnV -an order of magnitude larger than the optical line width and provides a magnetic field insensitive transition.This strong coupling provides access to a new regime for quantum registers in diamond color centers, opening avenues for novel spin-photon entanglement and quantum sensing schemes for these well-studied emitters.

Anonymous

C. T. Nguyen, Денис Дмитриевич Сукачев, Mihir K. Bhaskar +8 more

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.