Quantum Measurements of Mechanical Oscillators

Mechanical oscillators provide unique opportunities in precision measurements of forces due to their high quality factors and versatility in coupling to various physical systems. Recently, the measurements of macroscopic mechanical oscillators arrived at the regime dominated by the quantum effects in the measurement process. Here, I discuss three recent experiments conducted with radio-frequency mechanical oscillators cooled down to near-ground state, which are tightly coupled to and probed by microwave photons. The interplay between the mechanical oscillator and microwave photons manifests Heisenberg’s uncertainty relations in various ways, and their strong mutual interaction allows manipulation and utilization of the fundamental quantum back-actions.