Bulk and surface loss in superconducting transmon qubits. (3rd March 2016)

• Record Type: Journal Article
• Authors: Dial, Oliver; McClure, Douglas T; Poletto, Stefano; Keefe, G A; Rothwell, Mary Beth; Gambetta, Jay M; Abraham, David W; Chow, Jerry M; Steffen, Matthias
• Is Part Of: Superconductor science & technology. Volume 29:Number 4(2016:Apr.)
• Publication Date: 2016-03-03
• Subjects: transmon -- sapphire -- loss tangent -- surface loss; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/0953-2048/29/4/044001
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: Decoherence of superconducting transmon qubits is purported to be consistent with surface loss from two-level systems on the substrate surface. Here, we present a study of surface loss in transmon devices, explicitly designed to have varying sensitivities to different surface loss contributors. Our experiments also encompass two particular different sapphire substrates, which reveal the onset of a yet unknown additional loss mechanism outside of surface loss for one of the substrates. Tests across different wafers and devices demonstrate substantial variation, and we emphasize the importance of testing large numbers of devices for disentangling different sources of decoherence.