Analyzing the Toffoli gate in disordered circuit QED

Abstract

We study the effects of imperfections on the fidelity of the Toffoli gate recently realized in a circuit~QED setup using quantum control methods. The noise is introduced in the interqubits interactions. The coupling constants are no longer fixed; instead, they fluctuate around average values obeying some given probability density functions characterizing the dynamical-imperfection case. We also consider the static-imperfection case in which the values of the coupling constants are not exactly known. We obtain a more robust gate by modifying the quantum optimization problem using a weighted average of the fidelity over an interval of coupling values as the objective functional.