High-speed quantum operations of bosonic modes for superconducting circuits

Fast universal control of coupled discrete and continuous variable quantum systems is key to state preparation, measurement, and error correction of qubits encoded in oscillators. Though an existence proof exists, constructing efficient, high-fidelity sequences for controlling oscillator states is an open problem in non-Abelian quantum signal processing. We propose and numerically demonstrate an optimization technique that achieves high speed and fidelity for quantum state preparation and CPTP map implementation in an experimentally accessible regime. Our method ​provides exact fidelity evaluations for bosonic encodings including Gottesman-Kitaev-Preskill (GKP) and cat qubits.