Calibration of flux crosstalk in large-scale flux-tunable superconducting quantum circuits

TL;DR

This paper introduces an iterative, model-independent calibration method for flux crosstalk in large superconducting quantum circuits, significantly reducing calibration errors and enabling more precise control of flux-tunable qubits.

Contribution

A novel iterative calibration approach that is circuit model independent and improves flux crosstalk calibration accuracy in complex superconducting quantum circuits.

Findings

Calibration errors below 0.17% achieved

Method successfully applied to circuits with up to 27 control loops

Automated calibration process enhances precision in flux control

Abstract

Magnetic flux tunability is an essential feature in most approaches to quantum computing based on superconducting qubits. Independent control of the fluxes in multiple loops is hampered by crosstalk. Calibrating flux crosstalk becomes a challenging task when the circuit elements interact strongly. We present a novel approach to flux crosstalk calibration, which is circuit model independent and relies on an iterative process to gradually improve calibration accuracy. This method allows us to reduce errors due to the inductive coupling between loops. The calibration procedure is automated and implemented on devices consisting of tunable flux qubits and couplers with up to 27 control loops. We devise a method to characterize the calibration error, which is used to show that the errors of the measured crosstalk coefficients are all below 0.17%.