Quantum entanglement of a tunneling spin with mechanical modes of a torsional resonator

TL;DR

This paper investigates how a tunneling macrospin interacts with a torsional resonator, revealing entanglement effects that influence decoherence and mechanical mode splitting, relevant for magnetic molecule-nanoresonator experiments.

Contribution

It provides a detailed quantum analysis of spin-mechanical coupling, highlighting entanglement-induced decoherence and mechanical mode splitting in nanoresonator systems.

Findings

Entanglement causes decoherence of spin tunneling.

Mechanical mode splitting occurs at resonance for larger oscillators.

Results are applicable to magnetic molecule and nanoresonator experiments.

Abstract

We solve Schr\"odinger equation describing a tunneling macrospin coupled to a torsional oscillator. Energy spectrum is studied for various quantum regimes. Magnetic susceptibility and noise spectrum are computed. We show that entanglement of the spin with mechanical modes of a subnanometer oscillator results in the decoherence of spin tunneling. For larger oscillators the presence of a tunneling spin can be detected through splitting of the mechanical mode at the resonance. Our results apply to experiments with magnetic molecules coupled to nanoresonators.