Effects of Laser-Annealing on Fixed-Frequency Superconducting Qubits

TL;DR

This paper demonstrates an automated laser-annealing technique for superconducting qubits that preserves coherence, improves performance, and offers insights into physical mechanisms, aiding scalability of quantum processors.

Contribution

It introduces an automated laser-annealing apparatus for superconducting qubits, showing coherence preservation, performance enhancement, and physical modeling for scalable quantum device fabrication.

Findings

Two-fold increase in qubit coherence after laser-annealing

Successful noise spectroscopy revealing defect changes

Demonstration of aging stability on wafer scale

Abstract

As superconducting quantum processors increase in complexity, techniques to overcome constraints on frequency crowding are needed. The recently developed method of laser-annealing provides an effective post-fabrication method to adjust the frequency of superconducting qubits. Here, we present an automated laser-annealing apparatus based on conventional microscopy components and demonstrate preservation of highly coherent transmons. In one case, we observe a two-fold increase in coherence after laser-annealing and perform noise spectroscopy on this qubit to investigate the change in defect features, in particular two-level system defects. Finally, we present a local heating model as well as demonstrate aging stability for laser-annealing on the wafer scale. Our work constitutes an important first step towards both understanding the underlying physical mechanism and scaling up laser-annealing of superconducting qubits.