@article{c7652ca372a44fc5b66a84c3e6aef63c,
title = "Understanding degenerate ground states of a protected quantum circuit in the presence of disorder",
abstract = "A recent theoretical proposal suggests that a simple circuit utilizing two superinductors may produce a qubit with ground-state degeneracy [Brooks, Phys. Rev. A 87, 052306 (2013)PLRAAN1050-294710.1103/PhysRevA.87.052306]. We perform a full circuit analysis along with exact diagonalization of the circuit Hamiltonian to elucidate the nature of the spectrum and low-lying wave functions of this 0-π device. We show that the ground-state degeneracy is robust to disorder in charge, flux, and critical current as well as insensitive to modest variations in the circuit parameters. Our treatment is nonperturbative, provides access to excited states and matrix elements, and is immediately applicable also to intermediate parameter regimes of experimental interest.",
author = "Dempster, {Joshua M.} and Bo Fu and Ferguson, {David G.} and Schuster, {D. I.} and Jens Koch",
note = "Funding Information: We thank A. Houck, J. Lawrence, A. C. Y. Li, D. McKay, T. Yu, and G. Zhu for stimulating discussions. This research was supported by the NSF under Grants No. PHY-1055993 (J.D., B.F., D.G.F., J.K.), No. DMR-0805277 (D.G.F.), No. DMR-1151839 (D.I.S.), by the US Army Research Office under Grant No. W911NF-12-1-0608 (D.I.S.), by the Sloan Foundation (D.I.S.), and by the Packard Foundation (D.I.S.). Funding Information: This research was supported by the NSF under Grants No. PHY-1055993 (J.D., B.F., D.G.F., J.K.), No. DMR-0805277 (D.G.F.), No. DMR-1151839 (D.I.S.), by the US Army Research Office under Grant No. W911NF-12-1-0608 (D.I.S.), by the Sloan Foundation (D.I.S.), and by the Packard Foundation (D.I.S.). Publisher Copyright: {\textcopyright} 2014 American Physical Society.",
year = "2014",
month = sep,
day = "24",
doi = "10.1103/PhysRevB.90.094518",
language = "English (US)",
volume = "90",
journal = "Physical Review B - Condensed Matter and Materials Physics",
issn = "1098-0121",
publisher = "American Physical Society",
number = "9",
}