Protected josephson rhombus chains

Matthew T. Bell, Joshua Paramanandam, Lev B. Ioffe, Michael E. Gershenson

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


We have studied the low-energy excitations in a minimalistic protected Josephson circuit which contains two basic elements (rhombi) characterized by the π periodicity of the Josephson energy. Novel design of these elements, which reduces their sensitivity to the offset charge fluctuations, has been employed. We have observed that the lifetime T1 of the first excited state of this quantum circuit in the protected regime is increased up to 70μs, a factor of ∼100 longer than that in the unprotected state. The quality factor ω01T1 of this qubit exceeds 106. Our results are in agreement with theoretical expectations; they demonstrate the feasibility of symmetry protection in the rhombus-based qubits fabricated with existing technology.

Original languageEnglish (US)
Article number167001
JournalPhysical review letters
Issue number16
StatePublished - Apr 25 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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