Room-temperature Mechanical Resonator with a Single Added or Subtracted Phonon

TL;DR

This paper demonstrates the addition and subtraction of single phonons in a room-temperature mechanical oscillator using quantum measurement techniques, revealing non-Gaussian states and confirming phonon number doubling.

Contribution

It introduces a method to herald single phonon addition and subtraction at room temperature, enabling quantum state control of a 4GHz mechanical oscillator.

Findings

Successful phonon addition and subtraction at 300K

Observation of non-Gaussian phase-space distributions

Confirmation of phonon number doubling after operations

Abstract

A room-temperature mechanical oscillator undergoes thermal Brownian motion with an amplitude much larger than the amplitude associated with a single phonon of excitation. This motion can be read out and manipulated using laser light using a cavity-optomechanical approach. By performing a strong quantum measurement, i.e., counting single photons in the sidebands imparted on a laser, we herald the addition and subtraction of single phonons on the 300K thermal motional state of a 4GHz mechanical oscillator. To understand the resulting mechanical state, we implement a tomography scheme and observe highly non-Gaussian phase-space distributions. Using a maximum likelihood method, we infer the density matrix of the oscillator and confirm the counter-intuitive doubling of the mean phonon number resulting from phonon addition and subtraction.