Flip-Chip Optomechanics
Cooling Mechanics and Mitigating Noise with Feedback and Nonlinearity
J. P. van Soest (TU Delft - QN/Steele Lab)
G.A. Steele – Promotor (TU Delft - QN/Steele Lab)
S. Groeblacher – Promotor (TU Delft - QN/Groeblacher Lab)
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Abstract
Detecting and influencing the motion of mechanical resonators has been a major topic in the study of fundamental physics and sensor technology. Optomechanical systems are particularly suitable for this due to their flexibility in design, causing them to be applicable in a wide range of parameter regimes. However, for all optomechanical systems there is a long-standing challenge to increase the single photon coupling strength. Whereas there are many ongoing developments in the field of linear optomechanics, there has been an increasing interest in nonlinear optomechanical systems. Namely, as this is a requirement for the creation of a massive superposition state in these platforms, treading the boundary between quantum mechanics and general relativity. In this thesis we couple a mesoscopic membrane to a superconducting microwave cavity in a flip-chip geometry. The silicon nitride membrane is embedded inside an in-substrate phononic shield. Its resonance mode has a large effective mass, while retaining a considerable zero-point fluctuation, making it an excellent candidate for gravitational quantum experiments. Developing this platform, we overcome multiple challenges, such as mitigating noise and increasing the single photon coupling rate. Furthermore, we include a nonlinearity by coupling a cavity to a superconducting qubit, taking a first step towards nonlinear optomechanical experiments in a flip-chip system.