Coherence in a transmon qubit with epitaxial tunnel junctions

Martin P. Weides; Jeffrey S. Kline; Michael R. Vissers; Martin O. Sandberg; David S. Wisbey; Blake R. Johnson; Thomas A. Ohki; David P. Pappas

doi:10.1063/1.3672000

arXiv · 1111.5083

Coherence in a transmon qubit with epitaxial tunnel junctions

Martin P. Weides·Jeffrey S. Kline·Michael R. Vissers·Martin O. Sandberg·David S. Wisbey·Blake R. Johnson·Thomas A. Ohki·David P. Pappas

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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 .72-.86mu sec and the ensemble dephasing time T2 is slightly larger than T1. The dephasing time T2 (1.36mu sec) 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.

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Martin P. Weides, Jeffrey S. Kline, Michael R. Vissers, Martin O. Sandberg, David S. Wisbey, Blake R. Johnson, Thomas A. Ohki, David P. Pappas. 2011-12-09. Coherence in a transmon qubit with epitaxial tunnel junctions. https://doi.org/10.1063/1.3672000

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