Improving dc SQUID Phase Qubit Lifetimes through Increased Isolation from Bias Leads

ORAL

Abstract

The dc SQUID phase qubit has been plagued by a relatively short coherence time, T$_{2}$, and relaxation time, T$_{1}$ (tens of ns). By using a sapphire substrate and small (15 $\mu $m$^{2}$ or less) Al/AlO$_{x}$/Al junctions the performance of the qubit has improved to the point where the impedance of the bias leads is the main source of dissipation and decoherence in the device. We identify the main circuit parameters that effect the isolation (junction capacitance, loop inductance, etc.), and present designs to improve the qubits isolation from the bias leads.

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Authors

  • Anthony Przybysz

    University of Maryland, College Park, JQI, University of Maryland

  • Tauno Palomaki

    University of Maryland, College Park, JQI, University of Maryland

  • Sudeep Dutta

    University of Maryland, College Park, JQI, University of Maryland

  • Fred Wellstood

    University of Maryland, College Park, JQI, University of Maryland

  • Rupert Lewis

    University of Maryland, JQI, University of Maryland

  • Hanhee Paik

    JQI, University of Maryland

  • Hyeokshin Kwon

    University of Maryland, College Park, JQI, University of Maryland

  • Ben Cooper

    JQI, University of Maryland

  • Kaushik Mitra

    JQI, University of Maryland

  • Bob Anderson

    University of Maryland, College Park, Dept. of Physics \& Center for Nanophysics and Advanced Materials, University of Maryland, College Park, MD, JQI, University of Maryland

  • Alex Dragt

    JQI, University of Maryland

  • Chris Lobb

    University of Maryland, Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, University of Maryland, College Park, JQI, University of Maryland