Trapping of Weak Signal Pulses by Soliton and Trajectory Control in a Coherent Atomic Gas

TL;DR

This paper introduces a method using electromagnetically induced transparency in a cold atomic gas to trap weak signal pulses with solitons, enabling controlled trajectory manipulation and potential applications in low-light-level all-optical switching.

Contribution

It presents a novel approach for trapping and controlling weak optical signals via solitons in a coherent atomic medium with EIT, including trajectory manipulation using magnetic fields.

Findings

Weak signal pulses can be trapped and cotravel with solitons in EIT media.

Soliton trajectories can be controlled by magnetic field gradients.

The method enables potential low-light-level optical switching.

Abstract

We propose a method for trapping weak signal pulses by soliton and realizing its trajectory control via electromagnetically induced transparency (EIT). The system we consider is a cold, coherent atomic gas with a tripod or multipod level configuration. We show that, due to the giant enhancement of Kerr nonlinearity contributed by EIT, several weak signal pulses can be effectively trapped by a soliton and cotravel stably with ultraslow propagating velocity. Furthermore, we demonstrate that the trajectories of the soliton and the trapped signal pulses can be manipulated by using a Stern-Gerlach gradient magnetic field. As a result, the soliton and the trapped signal pulses display a Stern-Gerlach deflection and both of them can bypass an obstacle together. The results predicted here may be used to design all-optical switching at very low light level.