  An integrated photonic approach for complex quantum state generation through
dynamical Casimir effect (DCE) is demonstrated. This approach provides a scheme
to realize multipartite high-dimensional entangled states in the microwave (MW)
and terahertz (THz) regimes, through the modulation in a MW-resonator coupled
to an optical microresonator supporting temporal optical solitons. The states
at the MW-resonator evolve from the ground state, realizing real-photons from
the virtual photons at the ground state. The periodic modulation of the
MW-resonator through a Kerr-induced refractive index change in the optical
microresonator, along with the localized spatial distribution of the
dissipative Kerr solitons (DKSs), enables photon-pair generation and inter-mode
coupling at the MW-resonator. This allows generating highly persistent
multipartite high-dimensional entangled states in a wide range of spectrum. The
proposed approach paves the way for a hybrid integrated platform for generation
of multipartite entangled qudits (high-dimensional qubits) at the MW and THz
regimes using highly coherent ultra-short optical pulses in a monolithic
integrated platform. This architecture can act as an entangled state source, as
a necessary resource for exploiting a wide range of quantum protocols from
fault-tolerant computing to enhanced sensing and teleportation.
