Laser-annealing Josephson junctions for yielding scaled-up superconducting quantum processors

TL;DR

This paper introduces a post-fabrication frequency tuning method for superconducting qubits, significantly improving scalability by reducing frequency collisions and enabling larger quantum processors.

Contribution

It presents a systematic post-fabrication tuning technique using laser annealing to enhance qubit frequency precision, addressing frequency crowding in large-scale superconducting quantum circuits.

Findings

Nearly ten-fold improvement in qubit frequency setting precision.

High probability of collision-free qubit lattices with tuning.

Techniques are currently used in operational quantum systems.

Abstract

As superconducting quantum circuits scale to larger sizes, the problem of frequency crowding proves a formidable task. Here we present a solution for this problem in fixed-frequency qubit architectures. By systematically adjusting qubit frequencies post-fabrication, we show a nearly ten-fold improvement in the precision of setting qubit frequencies. To assess scalability, we identify the types of 'frequency collisions' that will impair a transmon qubit and cross-resonance gate architecture. Using statistical modeling, we compute the probability of evading all such conditions, as a function of qubit frequency precision. We find that without post-fabrication tuning, the probability of finding a workable lattice quickly approaches 0. However with the demonstrated precisions it is possible to find collision-free lattices with favorable yield. These techniques and models are currently employed in available quantum systems and will be indispensable as systems continue to scale to larger sizes.