This thesis experimental project aims at demonstrating strong resonant coupling between a long-lived quantum memory in the form of a nano-mechanical resonator, and a qubit. The mechanical resonator which is at the heart of this project is softly-clamped silicon-nitride membrane with an ultra-low dissipation rate of Г< 30 (1/s). The fluxonium qubit is composed of a Josephson junction shunted by an extremely large inductance. As result, such qubit has transitions in the MHz range with very good coherence properties. The strong coupling of these two quantum system will be used to demonstrate an original qubit-assisted cooling scheme, the generation of arbitrary phononic states such as Fock states or Schrödinger cat states, and to perform experimental tests of gravitational collapse models.

Research unit, lab, team:
UMR 8552, Laboratoire Kastler Brossel, Optomechanics and quantum measurements group

Thesis Director: Antoine Heidmann

Supervisors: Samuel Deléglise and Thibaut Jacqmin