Alternating-Bias Assisted Annealing of Josephson Junctions for Qubits

Abstract:

Superconducting quantum processors based on qubits made with Josephson tunnel-junctions (JJs) are one of the leading platforms for realizing scalable fault-tolerant quantum computation (FTQC). To realize this goal, it has become clear that it will be necessary to address the issue of JJ homogeneity in order to more precisely tune the qubits frequencies.  Work towards this using the newly developed alternating-bias assisted annealing (ABAA) technique will be discussed. ABAA illuminates a promising path towards precision tuning of qubit frequency while attaining higher coherence due to an apparent reduction in junction loss. Here, we demonstrate precision tuning of the qubits by performing ABAA at room temperature using commercially available test equipment and characterizing the impact of junction relaxation and aging on resistance spread after tuning. A study of the structural properties of the material using transmission electron microscopy will be given with some thoughts of what the driving mechanism for ABAA is at the atomic scale.