Design and application of high-speed and high-precision CV gate on IBM Q OpenPulse system

Faster and more precise physical processing of quantum gate, by suitably designing a pulse sequence to implement the target gate, will greatly improve the performance of quantum algorithms in the presence of noise. In this paper, we demonstrate that, by employing OpenPulse design kit for IBM Q devices, the controlled-V gate (CV gate) can be implemented in about 34.5% shorter gate time, with 0.66% improvement in the average gate fidelity, compared to the standard version provided there. Then, based on the theory of Cartan decomposition, we show that the performance of several two-qubit gates containing CV gates can also be improved. Moreover, the average gate fidelity of Toffoli gate can be improved to 96.16% from 90.23% achieved in the default IBM Q package. These results imply the importance of our CV gate implementation technique, which, as an additional option for the basis gate set design, may shorten the overall computation time and consequently improve the accuracy of several quantum algorithms.