Weak-light solitons and their active control in a parity-time-symmetric atomic system

We propose a realistic physical scheme to produce one-dimensional and two-dimensional weak-light solitons in an atomic system with PT symmetry. The system we suggest is a cold three-level atomic gas with two species and is driven by control and probe laser fields. We show that by the interference of two Raman resonances a highly adjustable probe-field refractive index with PT symmetry in one and two dimensions can be realized. We further show that it is possible to produce various light solitons when the weak nonlinearity of the probe field is taken into account. Due to the resonant character of the system, the light solitons obtained in one and two dimensions have extremely low light power (at the level of nanowatts). In addition, we demonstrate that the stability of these light solitons can be actively controlled via PT phase transition of the system.