Persistent Control of a Superconducting Qubit by Stroboscopic Measurement Feedback

In sensing-feedback control of a quantum system, optimizing the timing of the sensing measurements turns out to be a key to getting around the fundamental difficulty that a measurement can randomly change the system's state. Achieving optimal timing by combining technical advances with conceptual physical insight, researchers demonstrate, for the first time, high-fidelity control of a superconducting qubit along time-dependent trajectories.