Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T41: Novel Superconducting Qubits II
11:30 AM–2:18 PM,
Thursday, March 17, 2022
Room: McCormick Place W-196C
Sponsoring Unit: DQI
Chair: Setiawan Wenming, University of Chicago
Abstract: T41.00003 : Progress Towards a Protected Qubit Subspace within a Fluxonium Molecule*
11:54 AM–12:06 PM
Andrew A Houck
Protected qubits possess inherent immunity to both depolarization and pure dephasing processes. This noise protection is owed to both circuit design and parameter choices for which wavefunctions of logical states simultaneously exhibit disjoint support as well as sweet spots. The former suppresses spontaneous qubit transitions, the latter renders the qubit energy splitting first or second order insensitive to noise thus reducing pure dephasing. Here, we present recent work towards improving noise protection beyond the level demonstrated with the “soft” 0- qubit , instead employing a fluxonium molecule circuit . We discuss our results and the general competing constraints encountered in engineering protected qubits.
 A. Gyenis, P. S. Mundada, A. Di Paolo, T. Hazard, X. You, D. Schuster, J. Koch, A. Blais and A. A. Houck, PRX Quantum 2, 010339 (2021).
 A. Kou, W. C. Smith, U. Vool, R. T. Brierley, H. Meier, L. Frunzio, S. M. Girvin, L. I. Glazman, and M. H. Devoret, Phys. Rev. X 7, 031037 (2017)
*This work was supported by the Army Research Office (HIPS W911NF1910016) and the National Science Foundation (MRSEC DMR-1420541).
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