Generation of mechanical interference fringes by multi-photon counting

TL;DR

This paper introduces a new optomechanical method using multi-photon quantum measurements to create and observe quantum superposition states in macroscopic mechanical resonators, overcoming previous limitations.

Contribution

The authors propose a novel scheme that relaxes the need for strong single-photon coupling and enhances scalability, enabling larger superposition states and phase superresolution in mechanical systems.

Findings

Demonstrated multi-photon-counting technique on a mechanical thermal state

Observed interference fringes indicating phase superresolution

Method is resilient to optical loss and thermal decoherence

Abstract

Exploring the quantum behaviour of macroscopic objects provides an intriguing avenue to study the foundations of physics and to develop a suite of quantum-enhanced technologies. One prominent path of study is provided by quantum optomechanics which utilizes the tools of quantum optics to control the motion of macroscopic mechanical resonators. Despite excellent recent progress, the preparation of mechanical quantum superposition states remains outstanding due to weak coupling and thermal decoherence. Here we present a novel optomechanical scheme that significantly relaxes these requirements allowing the preparation of quantum superposition states of motion of a mechanical resonator by exploiting the nonlinearity of multi-photon quantum measurements. Our method is capable of generating non-classical mechanical states without the need for strong single photon coupling, is resilient against optical loss, and offers more favourable scaling against initial mechanical thermal occupation than existing schemes. Moreover, our approach allows the generation of larger superposition states by projecting the optical field onto NOON states. We experimentally demonstrate this multi-photon-counting technique on a mechanical thermal state in the classical limit and observe interference fringes in the mechanical position distribution that show phase superresolution. This opens a feasible route to explore and exploit quantum phenomena at a macroscopic scale.