Quantum Entanglement of a Tunneling Spin with Mechanical Modes of a Torsional Resonator

D A Garanin,E M Chudnovsky

doi:10.1103/physrevx.1.011005

Abstract

A nanomagnet coupled to a mechanical rotational oscillator is predicted to quantum mechanically flip its magnetic poles in resonance with the oscillator. Their ``choreographed dance'' together can be detected experimentally.

Highlights

There has been enormous progress in measurements of individual nanomagnets [1], microcantilevers, and microresonators [2,3,4,5,6,7,8,9,10,11,12,13,14,15]
Experiments have demonstrated that a mechanical torque induced by the rotation of the magnetic moment may be used for developing high-sensitivity magnetic probes and for actuation of microelectromechanical devices
The underlying physics is a direct consequence of the conservation of the total angular momentum: spin plus orbital

Summary

INTRODUCTION

There has been enormous progress in measurements of individual nanomagnets [1], microcantilevers, and microresonators [2,3,4,5,6,7,8,9,10,11,12,13,14,15]. The underlying physics is a direct consequence of the conservation of the total angular momentum: spin plus orbital While this effect is clear, the mechanism by which the angular momentum of individual spins gets transferred to the rotational motion of a body as a whole is less understood. These two problems have one common feature: The spin tunneling becomes suppressed when the body containing the spin is too light The physics behind this effect is quite clear [24]. At small I, such rotations cost so much energy that the tunneling in the ground state becomes frozen This effect is conceptually similar to the decoherence and freezing of the tunneling of a particle in a double-well potential due to dissipation [25]. In resonators of greater size, the spin coherence is preserved, and the presence of a tunneling spin can be detected by observing frequency splitting of mechanical oscillations

THE MODEL

ENERGY SPECTRUM AND STATIC SUSCEPTIBILITY

SPIN DYNAMICS

DISCUSSION