The levitation of micro-particles has experienced a rapid development in the last ten years due to its numerous applications, in particular for the study of the quantum decoherence of macroscopic objects or in metrology. Recently, researchers have succeeded in cooling the motion of a levitating silica ball and reaching the ground state of the center of mass. The generation of non-Gaussian quantum states of motion nevertheless requires a non-linear coupling of the particle with an external system such as a two-level quantum system.

The NV center of diamond is an ideal candidate for this purpose due to its exceptional quantum properties. Moreover, these magnetic impurities naturally couple to the spin modes of a levitating diamond in the presence of a magnetic field.

A team from the Physics Laboratory of ENS has taken a further step in the study of this coupling by observing a new form of magnetism of NVs centers allowing a high degree of control of the orientation of a levitating diamond. For magnetic fields higher than 0.1T, the magnetism of the NV center changes from a paramagnetic state to a diamagnetic state. In the diamagnetic regime, the torque exerted by the NV centers on the diamond is such that the diamond is oriented to align the axis of the NV centers with the direction of the external magnetic field. This is the first observation of diamagnetism of a purely spin nature, a result that could find applications in the creation of non-Gaussian states of motion as well as in biology.

Alignment of a levitating diamond with an external magnetic field using NV centers




DOI: 10.1103/PhysRevLett.128.117203

Author affiliation:
Laboratoire de physique de L’École normale supérieure (LPENS, ENS Paris/CNRS/Sorbonne Université/Université de Paris)

Corresponding author: Gabriel Hetet
Communication contact: L’équipe de communication