Fast quantum gates based on Landau-Zener-St\"uckelberg-Majorana transitions

TL;DR

This paper develops analytical methods for implementing fast, robust quantum gates using Landau-Zener-Stückelberg-Majorana transitions, optimizing parameters to reduce decoherence effects especially in small gap qubits.

Contribution

It introduces analytical equations for precise control of single and two-qubit gates via sinusoidal pulses, enhancing speed and robustness of quantum operations.

Findings

Analytical formulas for driving parameters enable precise gate implementation.

Optimal regimes identified to minimize decoherence effects.

Proposed the bSWAP as a robust two-qubit gate.

Abstract

Fast quantum gates are of paramount importance for enabling efficient and error-resilient quantum computations. In the present work we analyze Landau-Zener-St\"uckelberg-Majorana (LSZM) 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 focus in 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 results focus on the study of the single qubit $X_{\frac{\pi}{2}}$, $Y_{\frac{\pi}{2}}$ and identity gates. Also, we propose the $\sqrt{\rm{bSWAP}}$ as the simplest two-qubit gate attainable through a robust LZSM driving protocol.