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 · Physical Review Applied · 2017
In state-of-the-art quantum processors, the time spent tuning gates is a significant portion of experimental run time, and could continue to grow, as number of qubits and achievable fidelities both rise. The authors devise a tune-up protocol that realizes a tenfold speed-up over traditional methods, by constructing a cost function using real-time correlations of the outcomes of nondemolition measurements. This method can be readily generalized to other tune-up problems, including two-qubit gates and measurement operations, and can be parallelized for multi-qubit settings.