Cavity nano-optomechanics in the ultrastrong coupling regime with ultrasensitive force sensors

TL;DR

This paper demonstrates that ultrasensitive nanowire-based optomechanical systems can achieve the ultrastrong coupling regime, enabling single photons to significantly displace mechanical oscillators, opening new avenues for quantum control.

Contribution

The study introduces a nanowire-in-fiber microcavity system that reaches the ultrastrong coupling regime, surpassing previous limitations of weak single-photon interactions.

Findings

Achieved ultrastrong optomechanical coupling with a nanowire system.

Mapped the vectorial optomechanical coupling strength.

Revealed the intracavity optomechanical force field.

Abstract

In a canonical optomechanical system, mechanical vibrations are dynamically encoded on an optical probe field which reciprocally exerts a backaction force. Due to the weak single photon coupling strength achieved with macroscopic oscillators, most of existing experiments were conducted with large photon numbers to achieve sizeable effects, thereby causing a dilution of the original optomechanical non-linearity. Here, we investigate the optomechanical interaction of an ultrasensitive suspended nanowire inserted in a fiber-based microcavity mode. This implementation allows to enter far into the hitherto unexplored ultrastrong optomechanical coupling regime, where one single intracavity photon can displace the oscillator by more than its zero point fluctuations. To fully characterize our system, we implement nanowire-based scanning probe measurements to map the vectorial optomechanical coupling strength, but also to reveal the intracavity optomechanical force field experienced by the nanowire. This work establishes that the single photon cavity optomechanics regime is within experimental reach.