Low frequency correlated charge noise measurements across multiple energy transitions in a tantalum transmon

TL;DR

This study investigates low frequency charge noise in high-coherence tantalum transmon qubits, revealing rare, discrete charge jumps and offering insights into charge dynamics across multiple energy levels.

Contribution

It introduces the observation of rare, discrete charge jumps as a dominant noise process in tantalum transmons, differing from previous continuous charge noise models.

Findings

Charge offset dynamics are dominated by rare, discrete jumps.

Charge noise behavior differs from previous low frequency studies.

High coherence enables precise multi-level charge fluctuation tracking.

Abstract

Transmon qubits fabricated with tantalum metal have been shown to possess energy relaxation times greater than 300 $\mu$s and, as such, present an attractive platform for high precision, correlated noise studies across multiple higher energy transitions. Tracking the multi-level fluctuating qudit frequencies with a precision enabled by the high coherence of the device allows us to extract the charge offset and quasi-particle dynamics. We observe qualitatively different charge offset behavior in the tantalum device than those measured in previous low frequency charge noise studies. In particular, we find the charge offset dynamics are dominated by rare, discrete jumps between a finite number of quasi-stationary charge configurations, a previously unobserved charge noise process in superconducting qubits.