Josephson “flying qubit” revival: Flux-based control optimization

Abstract

A decade ago, Josephson “flying qubits” based on adiabatic superconducting logic cells showed promise as quantum data buses, but their development stalled due to the incompatibility of traditional qubit control methods with their design. We revisit this concept by exploring the control of the inductively shunted two-junction superconducting interferometer (adiabatic quantum flux parametron, AQFP) in the quantum regime using unipolar magnetic field pulses generated by adiabatic superconducting electronics. Our research demonstrates the feasibility of high fidelity quantum operations (fidelity more than 99.99%) in this system via Landau–Zener tunneling. To this end, a method is proposed for selecting the duration and shape of control pulses to eliminate unwanted leakage into high-lying states in AQFP-based systems.