Identifying Sources of Decoherence at Defects and Interfaces in Superconducting Qubit Systems

ORAL

Abstract

Superconducting qubits have emerged as a platform technology for potentially addressing computational problems deemed intractable with classical computing. Despite recent advances enabling coherence lifetimes on the order of hundreds of μs, material quality and interfacial structures continue to curb performance. Two-level system defects in the superconductor and adjacent dielectric regions introduce stochastic noise and dissipate electromagnetic energy at cryogenic operating temperatures. Through a correlative approach combining secondary ion mass spectroscopy and advanced electron microscopy techniques, we systematically investigate interfaces associated with superconducting thin films to build a link between processing parameters, material structure, and resultant properties. We find that during film deposition, oxide and silicide layers form with varying stoichiometries at metal/substrate and metal/air interfaces. Additionally, we observe that lithography and etching procedures lead to the presence of impurity species such as hydrides, carbides, and fluorides, which can impact the superconducting properties, within the large-area contact pads and Josephson junctions.

*This material is based upon work supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under the contract No. DE-AC02-07CH11359. We thank Rigetti Computing for supporting the development of these devices. This work made use of the EPIC facility of Northwestern University’s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN.

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Publication: https://arxiv.org/abs/2108.13539

Presenters

  • Akshay A Murthy

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab

Authors

  • Akshay A Murthy

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab

  • Paul M Das

    • Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
    • Northwestern University

  • Cameron J Kopas

    • Rigetti Quantum Computing
    • Rigetti Computing

  • Stephanie M Ribet

    • Department of Materials Science and Engineering, Northwestern University; International Institute of Nanotechnology, Northwestern University
    • Northwestern University

  • Matthew J Reagor

    • Rigetti Quantum Computing

  • Vinayak P Dravid

    • Northwestern University
    • Department of Materials Science and Engineering, Northwestern University; International Institute of Nanotechnology, Northwestern University; NUANCE Center, Northwestern U.

  • Roberto dos Reis

    • Department of Materials Science and Engineering, Northwestern University; NUANCE Center, Northwestern University
    • Northwestern University

  • Mattia Checchin

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab

  • Alexander Romanenko

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab

  • Anna Grassellino

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab