  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.
