Equivalence of flexible stripline and coaxial cables for superconducting qubit control and readout pulses

TL;DR

This study compares flexible stripline and coaxial cables for superconducting qubit control, finding no measurable difference in qubit coherence, thus enabling more scalable and integrated quantum computing architectures.

Contribution

It demonstrates that flexible stripline transmission lines are equivalent to coaxial cables for qubit control, supporting scalable quantum device integration.

Findings

No measurable difference in qubit coherence between the two wiring methods.

Flexible striplines enable large-scale integration with planar layouts.

Repeated measurements over extended periods confirm the equivalence.

Abstract

We report a comparative study on microwave control lines for a transmon qubit using: (i) flexible stripline transmission lines, and (ii) semi-rigid coaxial cables. During each experiment we performed repeated measurements of the energy relaxation and coherence times of a transmon qubit using one of the wiring configurations. Each measurement run spanned 70 h to 250 h of measurement time, and four separate cooldowns were performed so that each configuration could be tested twice. From these datasets we observe that changing the microwave control lines from coaxial cables to flexible stripline transmission lines does not have a measurable effect on coherence compared to thermal cycling the system, or random coherence fluctuations. Our results open up the possibility of large scale integration of qubit control lines with integrated component with planar layouts on flexible substrate.