Restless Tuneup of High-Fidelity Qubit Gates

M. A. Rol, C. C. Bultink, T. E. O'Brien, S. R. De Jong, L. S. Theis, X. Fu, F. Luthi, R. F.L. Vermeulen, J. C. De Sterke, A. Bruno, D. Deurloo, R. N. Schouten, F. K. Wilhelm, L. Dicarlo

Research output: Contribution to journalArticleScientificpeer-review

48 Citations (Scopus)
78 Downloads (Pure)


We present a tuneup protocol for qubit gates with tenfold speedup over traditional methods reliant on qubit initialization by energy relaxation. This speedup is achieved by constructing a cost function for Nelder-Mead optimization from real-time correlation of nondemolition measurements interleaving gate operations without pause. Applying the protocol on a transmon qubit achieves 0.999 average Clifford fidelity in one minute, as independently verified using randomized benchmarking and gate-set tomography. The adjustable sensitivity of the cost function allows the detection of fractional changes in the gate error with a nearly constant signal-to-noise ratio. The restless concept demonstrated can be readily extended to the tuneup of two-qubit gates and measurement operations.

Original languageEnglish
Article number041001
JournalPhysical Review Applied
Issue number4
Publication statusPublished - 24 Apr 2017


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