Dynamical transitions in a modulated Landau-Zener model with finite driving fields

TL;DR

This paper presents an exactly solvable, modulated Landau-Zener model that maintains high-fidelity population transfer with finite, asymptotically vanishing driving fields, and analyzes the effects of environmental noise on the protocol.

Contribution

It introduces a novel, analytically solvable modulated Landau-Zener model with finite driving fields and studies its robustness against noise and dissipation effects.

Findings

Exact analytical solutions for the modulated Landau-Zener dynamics.

High-fidelity population transfer with finite, asymptotically vanishing driving fields.

Quantitative estimates of fidelity loss due to environmental noise.

Abstract

We investigate a special time-dependent quantum model which assumes the Landau-Zener driving form but with an overall modulation of the intensity of the pulsing field. We demonstrate that the dynamics of the system, including the two-level case as well as its multi-level extension, is exactly solvable analytically. Differing from the original Landau-Zener model, the nonadiabatic effect of the evolution in the present driving process does not destroy the desired population transfer. As the sweep protocol employs only the finite driving fields which tend to zero asymptotically, the cutoff error due to the truncation of the driving pulse to the finite time interval turns out to be negligibly small. Furthermore, we investigate the noise effect on the driving protocol due to the dissipation of the surrounding environment. The losses of the fidelity in the protocol caused by both the phase damping process and the random spin flip noise are estimated by solving numerically the corresponding master equations within the Markovian regime.