Kerr effect in Y-configuration double-quantum-dot system

We have introduced a Y-configuration model from the double-quantum-dot (QD) system to study third-order Kerr nonlinearity based on the density-matrix method. Inhomogeneity in QDs has been included in the calculations of the real (Kerr) and imaginary (absorption) parts of the density matrix, which has not been covered in the earlier Kerr calculations. Our system exhibits high controllability with a single parameter. Giant Kerr dispersion, propagation without distortion, wide electromagnetic-induced transparency, and switching between subluminal to superluminal propagation are obtained by tuning its fields. Controlling and cycling fields can also control the system in addition to the pump field.