QDev Seminar: Juha Pirkkalainen – University of Copenhagen

QDev Seminar: Juha Pirkkalainen


The study of quantum mechanics with mechanical systems has gained a lot of momentum recently. Massive mechanical resonators enable the study of quantum mechanics in a completely new parameter regime, e.g., testing gravitational decoherence models. Superconducting qubits provide a flexible source for creating arbitrary quantum states. Their metal islands can be small in dimensions and therefore they couple capacitively very strongly to mechanical resonators. Even so the coupling to mechanics remains small and the qubit is required to stay coherent during the transfer of quantum states. The coherence times of superconducting qubits have increased exponentially during the past 15 years and now coherence times of microseconds can be reached by shunting charge noise. In this talk I will present our work on coupling transmon qubits to bridge and drum resonators. I will show how the qubit can be coherently coupled to a driven mechanical resonator by using a sideband drive which brings the two system effectively to resonance. I discuss how the coupling can be increased further to transfer quantum states from the qubit to the mechanics at its ground state.