Robust multi-mode superconducting circuit optimized for quantum information processing

TL;DR

This paper introduces a multi-mode superconducting circuit optimized for quantum computing, demonstrating enhanced coherence, control, and robustness against fabrication errors compared to existing single-mode devices.

Contribution

The authors design and experimentally validate a multi-mode superconducting circuit that surpasses traditional devices in coherence, control, and fabrication robustness for quantum information processing.

Findings

Achieves coherence times and gate ratios significantly better than Transmon and Fluxonium.

Demonstrates robustness against fabrication errors.

Shows improved resilience to charge and magnetic flux fluctuations.

Abstract

Multi-mode superconducting circuits offer a promising platform for engineering robust systems for quantum computation. Previous studies indicate that single-mode devices cannot be engineered to simultaneously exhibit resilience against multiple decoherence sources due to conflicting requirements. In contrast, multi-mode systems offer increased flexibility and have proven capable of overcoming these fundamental limitations. Here, we present a multi-mode device optimized for quantum information processing. It features an anharmonicity of a third of the qubit frequency and reduced energy dispersion caused by charge and magnetic flux fluctuations. It exhibits improvements over the fundamental errors limiting Transmon and Fluxonium coherence and control, achieving ratios between the total coherence time and the gate time $T_2/t_g$ one order of magnitude larger than Transmon and two times larger than Fluxonium for microwave charge drives, assuming equal dielectric and inductive loss quality factors and limited drive strength. It furthermore demonstrates robustness against fabrication errors, a major limitation in many proposed multi-mode devices.