Fidelity and Fidelity Susceptibility of Pulses in Dispersive Media

TL;DR

This paper investigates how fidelity and fidelity susceptibility can describe pulse distortion in dispersive media, revealing critical propagation distances where pulses undergo dramatic changes, useful for optimizing pulse transmission.

Contribution

It introduces the application of fidelity and FS concepts from quantum critical phenomena to analyze pulse propagation in dispersive media, highlighting their effectiveness in detecting pulse distortion.

Findings

Fidelity and FS change dramatically at a critical propagation distance.

Dispersive strength and pulse properties influence the occurrence of dramatic fidelity changes.

Fidelity and FS can determine the maximal effective propagation region.

Abstract

Motivated by the growing importance of the fidelity and fidelity susceptibility (FS) in quantum critical phenomena, we use these concepts to describe the pulse propagation inside the dispersive media. It is found that there is a dramatic change in the fidelity and the FS of the pulse at a critical propagation distance inside a dispersive medium, and whether such a dramatic change for a light pulse occurs or not strongly depends on both the dispersive strength of the media and the pulse property. We study in detail about the changes of the fidelity and the FS for both a smooth and a truncated Gaussian pulse through the abnormal and normal dispersive media, where the group velocities are well defined. Our results show that both the fidelity and the FS could be very useful to determine whether the pulse is completely distorted or not at the critical distance, therefore it would be very helpful to find the maximal effective propagation region of the pulse's group velocity, in terms of the changes of the pulse's fidelity and FS.