Solitons in the two-dimensional fractional Schrödinger equation with radially symmetric PT potential

We investigate the properties of linear and nonlinear fiber models described by the two-dimensional fractional Schrödinger equation with a radially symmetric parity-time (PT) potential. A nonlinear twisted multicore fiber is constructed with alternating amplifying and absorbing cores, which meet the requirements of the PT symmetry. At the PT symmetry breaking point, the threshold level of gain/loss is non-monotonic function of the fiber twisting rate, which can be reduced to nearly zero. The increasing nonlinearity leads to the reduction of the symmetry-breaking threshold. Furthermore, it is shown that the coupling strength between neighboring cores, global energy transport of the linear modes, and the distribution characteristics of soliton solutions of the model depend on the Lévy index, nonlinearity, gain/loss, and the fiber twisting rate.