Investigating surface loss effects in superconducting transmon qubits

TL;DR

This study systematically investigates how the physical footprint of superconducting transmon qubits affects their coherence, revealing that surface loss dominates small footprints while other unknown mechanisms limit larger ones.

Contribution

It provides a comprehensive analysis of footprint-dependent loss mechanisms in transmon qubits, guiding optimized qubit design for improved coherence.

Findings

Small footprint qubits are limited by surface loss.

Large footprint qubits are limited by unidentified loss mechanisms.

Optimal qubit design balances footprint to maximize coherence.

Abstract

Superconducting qubits are sensitive to a variety of loss mechanisms including dielectric loss from interfaces. By changing the physical footprint of the qubit it is possible to modulate sensitivity to surface loss. Here we show a systematic study of planar superconducting transmons of differing physical footprints to optimize the qubit design for maximum coherence. We find that qubits with small footprints are limited by surface loss and that qubits with large footprints are limited by other loss mechanisms which are currently not understood.