Simultaneous Monitoring of Fluxonium Qubits in a Waveguide

A. Kou, W. C. Smith, U. Vool, I. M. Pop, K. M. Sliwa, M. Hatridge, L. Frunzio, M. H. Devoret

Research output: Contribution to journalArticlepeer-review


Most quantum error-correcting codes assume that the decoherence of each physical qubit is independent of the decoherence of any other physical qubit. We can test the validity of this assumption in an experimental setup where a microwave feedline couples to multiple qubits by examining correlations between the qubits. We investigate the correlations between fluxonium qubits located in a single waveguide. Despite being in a wide-bandwidth electromagnetic environment, the qubits have measured relaxation times in excess of 100 μs. We use cascaded Josephson parametric amplifiers to measure the quantum jumps of two fluxonium qubits simultaneously. No correlations are observed between the relaxation times of the two fluxonium qubits, which indicates that the sources of relaxation are local to each qubit in our setup. Our correlation analysis can be generalized to different types of qubits and our architecture can easily be scaled to monitor larger numbers of qubits.

Original languageEnglish (US)
Article number064022
JournalPhysical Review Applied
Issue number6
StatePublished - Jun 14 2018
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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