Special CPM Seminar

Manipulating and Measuring States of an Optomechanical Resonator in the Quantum Regime

Yiqi Wang

Yale University

What is the largest and most tangible object to reveal purely quantum phenomena? Macroscopic mechanical devices in the quantum regime can play a crucial role in quantum communication, quantum sensing, and fundamental tests of quantum mechanics. In this talk, I will describe my recent progress toward manipulating a nanogram mechanical resonator in the quantum regime. The mechanical resonator is the density wave of superfluid helium-4 confined in a fiber cavity. The light as a gentle quantum “drumstick” is used to control the motion of the helium, while the helium in exchange encodes its information on the light. For larger objects, a myriad of different factors conspire to mask the quantum effect. I can circumvent some of these challenges by leveraging properties of superfluid helium and single photon counting techniques. The arrival times of Stokes and anti-Stokes photons reveal the resonator's phonon coherences. I demonstrate the phonon coherences of a thermal state near the motional ground state, a non-classical photon-phonon entangled state, and a high amplitude coherent state. These experiments explore the boundary of realizing quantum states in macroscopic objects and pave the avenue to deploy mechanical resonators in quantum-enhanced applications.