Mitigating Fast Controller Noise in Quantum Gates Using Optimal Control Theory

All quantum systems are subject to noise from the environment or external controls. This noise is a major obstacle to the realization of quantum technology; e.g., noise limits the fidelity of quantum gates. We employ Optimal Control Theory to study the generation of quantum single- and two-qubit gates in the presence of fast controller noise. Specifically, we explore a Markovian model of phase and amplitude noise, which degrades gate fidelity. We show that optimal control with such noise models generates control solutions to mitigate the loss of gate fidelity. The problem is formulated in Liouville space, employing a highly accurate numerical solver and the Krotov algorithm to solve optimal control equations.