Controlling long-lived mechanical oscillators with a transmon qubit (Part I)

The long lifetimes of mechanical oscillators at cryogenic temperatures combined with their compact geometry make them promising candidates as bosonic elements in a variety of quantum applications. However, achieving deterministic quantum control and long lifetimes in a single mechanical system remains a challenge, limiting the utility of quantum acoustics systems. Here, we demonstrate strong coupling between a transmon qubit and a silicon mechanical oscillator by utilizing an electrostatic bias field [1]. We verify that this system operates in the quantum ground state and use it to prepare non-classical states of motion. Additionally, we use the qubit as a sensitive probe for studying quantum decoherence of the mechanical oscillator. We find mechanical energy loss to be extremely small in our system, with the coherence limited by dephasing. We further find that dephasing can be effectively mitigated via dynamical decoupling operations, which are enabled by the transmon qubit in our system.

Part 1 of the talk introduces our quantum acoustics platform and presents experimental data confirming that the hybrid system operates in the strong coupling regime and achieves quantum ground state operation.

[1] Bozkurt, A. et al. Nat. Phys. 19(9), 1326-1332 (2023)