Strain-engineered nanoscale spin polarization reversal in diamond nitrogen-vacancy centers

TL;DR

This paper demonstrates that anisotropic lattice strain can reversibly control spin polarization in diamond NV centers, enabling precise manipulation of quantum states for advanced quantum technologies.

Contribution

It introduces strain engineering as a novel method to manipulate spin dynamics and polarization in NV centers, surpassing conventional cavity-based control techniques.

Findings

Giant shear strain gradients cause complete spin polarization reversal.

Strain-induced mixing of excited states alters intersystem crossing.

Spatial mapping shows sub-120 nm control of polarization.

Abstract

The ability to control solid-state quantum emitters is fundamental to advancing quantum technologies. The performance of these systems is fundamentally governed by their spin-dependent photodynamics, yet conventional control methods using cavities offer limited access to key non-radiative processes. Here we demonstrate that anisotropic lattice strain serves as a powerful tool for manipulating spin dynamics in solid-state systems. Under high pressure, giant shear strain gradients trigger a complete reversal of the intrinsic spin polarization, redirecting ground-state population from $|0\rangle$ to $|\pm 1\rangle$ manifold. We show that this reprogramming arises from strain-induced mixing of the NV center's excited states and dramatic alteration of intersystem crossing, which we quantify through a combination of opto-magnetic spectroscopy and a theoretical model that disentangles symmetry-preserving and symmetry-breaking strain contributions. Furthermore, the polarization reversal is spatially mapped with a transition region below 120 nm, illustrating sub-diffraction-limit control. Our work establishes strain engineering as a powerful tool for tailoring quantum emitter properties, opening avenues for programmable quantum light sources, high-density spin-based memory, and hybrid quantum photonic devices.