Readout and control of a single nuclear spin with a meta-stable electron spin ancilla

TL;DR

This paper demonstrates the control and readout of a single nuclear spin in diamond using a metastable electron spin ancilla, achieving high contrast optical readout and coherent nuclear manipulation at room temperature.

Contribution

It introduces a novel defect in diamond with a spin-free ground state, enabling long-lived nuclear spin coherence and advanced quantum control techniques.

Findings

High contrast optical readout of nuclear spins (up to 45%)

Coherent manipulation of nuclear spins via a metastable electron spin

Demonstration of nuclear magnetic resonance and Rabi oscillations

Abstract

Electron and nuclear spins associated with point defects in insulators are promising systems for solid state quantum technology. While the electron spin usually is used for readout and addressing, nuclear spins are exquisite quantum bits and memory systems. With these systems single-shot readout of nearby nuclear spins as well as entanglement aided by the electron spin has been shown. While the electron spin in this example is essential for readout it usually limits nuclear spin coherence. This has set of the quest for defects with spin-free ground states. Here, we isolate a hitherto unidentified defect in diamond and use it at room temperature to demonstrate optical spin polarization and readout with exceptionally high contrast (up to 45%), coherent manipulation of an individual excited triplet state spin, and coherent nuclear spin manipulation using the triplet electron spin as a meta-stable ancilla. By this we demonstrate nuclear magnetic resonance and Rabi oscillations of the uncoupled nuclear spin in the spin-free electronic ground state. Our study demonstrates that nuclei coupled to single metastable electron spins are useful quantum systems with long memory times despite electronic relaxation processes.