Resolving the vacuum fluctuations of an optomechanical system using an artificial atom

TL;DR

This paper demonstrates how an artificial atom coupled to an optomechanical system can directly measure and verify quantum vacuum fluctuations, advancing quantum control and information processing capabilities.

Contribution

It introduces a method using a superconducting qubit to detect and verify quantum vacuum fluctuations in a macroscopic mechanical oscillator.

Findings

Successful ground state preparation of the mechanical oscillator

Detection of quantum vacuum fluctuations via photon/phonon-number distributions

Control of mechanical oscillators with non-Gaussian resources

Abstract

Heisenberg's uncertainty principle results in one of the strangest quantum behaviors: an oscillator can never truly be at rest. Even in its lowest energy state, at a temperature of absolute zero, its position and momentum are still subject to quantum fluctuations. Resolving these fluctuations using linear position measurements is complicated by the fact that classical noise can masquerade as quantum noise. On the other hand, direct energy detection of the oscillator in its ground state makes it appear motionless. So how can we resolve quantum fluctuations? Here, we parametrically couple a micromechanical oscillator to a microwave cavity to prepare the system in its quantum ground state and then amplify the remaining vacuum fluctuations into real energy quanta. Exploiting a superconducting qubit as an artificial atom, we measure the photon/phonon-number distributions during these optomechanical interactions. This provides an essential non-linear resource to, first, verify the ground state preparation and second, reveal the quantum vacuum fluctuations of the macroscopic oscillator's motion. Our results further demonstrate the ability to control a long-lived mechanical oscillator using a non-Gaussian resource, directly enabling applications in quantum information processing and enhanced detection of displacement and forces.