High Harmonic Generation with Many-Particle Coulomb Interaction in Graphene Quantum Dot

The multiphoton excitation and high harmonic generation (HHG) processes are considered using the microscopic quantum theory of nonlinear interaction of strong coherent electromagnetic (EM) radiation with rectangular graphene quantum dot (GQD) with zigzag edges and more than 80 atoms. The dynamic Hartree–Fock approximation has been used to consider the quantum dot-laser field nonlinear interaction at the nonadiabatic multiphoton excitation regime. The many-body Coulomb interaction is described in the extended Hubbard approximation. By numerical results, we show the significance of the rectangular GQD lateral size, shape, and EM wavefield orientation in rectangular GQD of the zigzag edge in the HHG process allowing for increasing the cutoff photon energy and the quantum yield of higher harmonics.