Optimizing fluxonium readout using quantum optimal control

The heavy fluxonium qubit has recently received significant attention due to its long coherence time and high-fidelity quantum gates. However, the same properties that make this qubit attractive, namely its low qubit frequency and delocalized computational states, limit the performance of standard readout schemes. Quantum controls that make use of the rich energy level structure and flux tunability of the fluxonium could enable significant improvement in qubit readout. To this end, we make use of a recently introduced quantum optimal control approach for open systems that allows us to optimize arbitrary controls while considering the full quantum system of a fluxonium coupled to its dissipative readout resonator. We investigate novel control schemes to improve the duration and fidelity of fluxonium readout by using time-dependent charge and flux drives which take advantage of the intrinsic system structure. We focus on developing experimentally realistic controls by using comprehensive numerical simulations and exploring protocols that would be straightforward to calibrate on an actual quantum device.