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

Abstract:

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.