Fast quantum gates based on Landau-Zener-Stückelberg-Majorana transitions

Abstract

Fast quantum gates are of paramount importance for enabling efficient and error-resilient quantum computations. In the present work we analyze Landau-Zener-Stückelberg-Majorana (LZSM) strong driving protocols, tailored to implement fast gates with particular emphasis on small-gap qubits. We derive analytical equations to determine the specific set of driving parameters for the implementation of single-qubit and two-qubit gates employing single-period sinusoidal pulses. Our approach circumvents the need to scan experimentally a wide range of parameters and instead it allows to concentrate on fine-tuning the device near the analytically predicted values. We analyze the dependence of relaxation and decoherence on the amplitude and frequency of the pulses, obtaining the optimal regime of driving parameters to mitigate the effects of the environment. Our study focus on the single-qubit Xπ2, Yπ2 and identity gates. Also, we propose the √bSWAP as the simplest two-qubit gate attainable through a robust LZSM driving protocol.