We present a tuneup protocol for qubit gates with tenfold speedup over traditional methods reliant on qubit initialization by energy relax- ation. This speedup is achieved by constructing a cost function for Nelder-Mead optimization from real-time correlation of non-demolition 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 detecting fractional reductions in gate error with constant signal- to-noise ratio. The restless concept here demonstrated can be readily extended to the tuneup of two-qubit gates and measurement operations.
*Research funded by IARPA, an ERC Synergy grant, Microsoft Research, and the China Scholarship Council.
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Authors
M.A. Rol
QuTech and the Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
C.C. Bultink
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
T.E. O'Brien
Instituut-Lorentz for Theoretical Physics,
S.R. de Jong
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
L.S. Theis
Theoretical Physics, Saarland Univ.
X. Fu
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
F. Luthi
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
R.F.L. Vermeulen
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
J.C. de Sterke
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
A. Bruno
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
D. Deurloo
Netherlands Organization for Applied Scientific Research (TNO) and QuTech, Delft Univ. Tech.
R.N. Schouten
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
F.K. Wilhelm
Theoretical Physics, Saarland Univ.
L. DiCarlo
QuTech and Kavli Institute of Nanoscience, Delft Univ. Tech.
