Coherent Sensing of a Mechanical Resonator with a Single-Spin Qubit

TLDR

Mechanical resonators at the nanoscale can couple to individual quantum systems via small forces such as gravitational, optical, electrical, and magnetic. The goal is to develop a technique that could detect mechanical zero‑point fluctuations, achieve strong single‑quantum spin‑phonon coupling, and enable quantum spin transducers. The authors show that a nitrogen‑vacancy spin coherently couples to a magnetized nanomechanical resonator and can sense its driven and Brownian motion with sub‑6‑picometer precision at ambient conditions.

Abstract

Mechanical systems can be influenced by a wide variety of small forces, ranging from gravitational to optical, electrical, and magnetic. When mechanical resonators are scaled down to nanometer-scale dimensions, these forces can be harnessed to enable coupling to individual quantum systems. We demonstrate that the coherent evolution of a single electronic spin associated with a nitrogen vacancy center in diamond can be coupled to the motion of a magnetized mechanical resonator. Coherent manipulation of the spin is used to sense driven and Brownian motion of the resonator under ambient conditions with a precision below 6 picometers. With future improvements, this technique could be used to detect mechanical zero-point fluctuations, realize strong spin-phonon coupling at a single quantum level, and implement quantum spin transducers.