Angle Locking of a Levitating Diamond using Spin-Diamagnetism

TL;DR

This paper demonstrates a method to lock the orientation of a levitating diamond using spin-diamagnetism, enabling stable NV center alignment for sensing and quantum applications.

Contribution

It introduces a novel technique to achieve angle locking of levitating diamonds via spin population inversion, improving stability without microwave control.

Findings

Diamond crystalline axis aligns with magnetic field with high precision.

The method enables stable NV center orientation in levitating diamonds.

Potential applications in biological sensing and spin-mechanics.

Abstract

The negatively charged nitrogen-vacancy (NV) center in nano- or micro- diamonds has emerged as a promising magnetic field sensor, as a candidate for hyper-polarizing paramagnetic species, as well as a tool for spin-mechanics at the nanoscale. However, NV-doped diamonds are presently not straightforwardly employable for these applications in a liquid or when levitating under atmospheric pressures due to the random angular Brownian motion which tends to rotate the NV quantization axis over the course of the measurments. Here, we report on angle locking of the crystalline axis of a trapped micro-diamond along an external magnetic field. Specifically, we use spin population inversion after a ground state level crossing of the NV center to turn the diamond into a diamagnet. The diamond crystalline axis naturally aligns to the magnetic field with high precision and in the absence of micro-wave, offering bright prospects for applications in biology and spin-mechanical platforms.