Proposal for a quantum delayed-choice experiment with a spin-mechanical setup

TL;DR

This paper proposes a feasible quantum delayed-choice experiment using a spin-mechanical system with a nitrogen-vacancy center and a mechanical resonator, enabling tests of quantum mechanics at a macroscopic scale.

Contribution

It introduces a novel protocol for a quantum delayed-choice experiment with massive objects, utilizing a spin-mechanical setup with NV centers and mechanical resonators.

Findings

Interference fringes observed depending on the resonator state

Quantum superposition of mechanical states enables superposition of wave and particle behaviors

Potential for fundamental tests of quantum mechanics on macroscopic objects

Abstract

We describe an experimentally feasible protocol for performing a variant of the quantum delayed-choice experiment with massive objects. In this scheme, a single nitrogen-vacancy (NV) center in diamond driven by microwave fields is dispersively coupled to a massive mechanical resonator. A double-pulse Ramsey interferometer can be implemented with the spin-mechanical setup, where the second Ramsey microwave pulse drives the spin conditioned on the number states of the resonator. The probability for finding the NV center in definite spin states exhibits interference fringes when the mechanical resonator is prepared in a specific number state. On the other hand, the interference is destroyed if the mechanical resonator stays in some other number states. The wavelike and particlelike behavior of the NV spin can be superposed by preparing the mechanical resonator in a superposition of two distinct number states. Thus a quantum version of Wheeler's delayed-choice experiment could be implemented, allowing of fundamental tests of quantum mechanics on a macroscopic scale.