Proposal to Test Quantum Wave-Particle Superposition on Massive Mechanical Resonators

TL;DR

This paper proposes a macroscopic quantum delayed-choice experiment using mechanical resonators controlled by nitrogen-vacancy spins, aiming to test quantum superpositions at a large scale and explore the quantum-classical boundary.

Contribution

It introduces a novel scheme employing nitrogen-vacancy centers and mechanical resonators to demonstrate and amplify superpositions in massive objects.

Findings

Mechanical phonons can be in superposition of wave and particle states.

Critical temperature identified for observing superpositions amidst environmental noise.

Mechanical mode squeezing amplifies single-phonon states to macroscopic levels.

Abstract

We present and analyze a proposal for a macroscopic quantum delayed-choice experiment with massive mechanical resonators. In our approach, the electronic spin of a single nitrogen-vacancy impurity is employed to control the coherent coupling between the mechanical modes of two carbon nanotubes. We demonstrate that a mechanical phonon can be in a coherent superposition of wave and particle, thus exhibiting both behaviors at the same time. We also discuss the mechanical noise tolerable in our proposal and predict a critical temperature below which the morphing between wave and particle states can be effectively observed in the presence of environment-induced fluctuations. Furthermore, we describe how to amplify single-phonon excitations of the mechanical-resonator superposition states to a macroscopic level, via squeezing the mechanical modes. This approach corresponds to the phase-covariant cloning. Therefore, our proposal can serve as a test of macroscopic quantum superpositions of massive objects even with large excitations. This work, which describes a fundamental test of the limits of quantum mechanics at the macroscopic scale, would have implications for quantum metrology and quantum information processing.