Coherence in a transmon qubit with epitaxial tunnel junctions

Weides, M. P. , Kline, J. S., Vissers, M. R., Sandberg, M. O., Wisbey, D. S., Johnson, B. R., Ohki, T. A. and Pappas, D. P. (2011) Coherence in a transmon qubit with epitaxial tunnel junctions. Applied Physics Letters, 99(26), 262502. (doi: 10.1063/1.3672000)

Abstract

We developed transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors. This multileveled qubit, patterned by use of all-optical lithography, is a step towards scalable qubits with a high integration density. The relaxation time T1 is 0.72−0.86 μs and the ensemble dephasing time T∗2T2* is slightly larger than T1. The dephasing time T2 (1.36 μs) is nearly energy-relaxation-limited. Qubit spectroscopy yields weaker level splitting than observed in qubits with amorphous barriers in equivalent-size junctions. The qubit’s inferred microwave loss closely matches the weighted losses of the individual elements (junction, wiring dielectric, and interdigitated capacitor), determined by independent resonator measurements.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Weides, Professor Martin
• Authors: Weides, M. P., Kline, J. S., Vissers, M. R., Sandberg, M. O., Wisbey, D. S., Johnson, B. R., Ohki, T. A., and Pappas, D. P.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Applied Physics Letters
• Publisher: AIP Publishing
• ISSN: 0003-6951
• ISSN (Online): 1077-3118