Quantum information science and imaging technologies reach some bottleneck due to limited scalability of non-classical sources. Generally, multipartite entanglement with N>2 suitable for quantum applications is difficult to achieve because of the low efficiency of the traditional schemes. The quantum nature of strong field processes occurring in high harmonic generation (HHG) has recently revealed the possibility of generating massively entangled quantum states that should come as a frequency comb of N entangled photons [Gor20]. Intrinsically, the HHG emission comes as a frequency comb and should exhibit N-partite entangled photons. Practically, the internship project will consist in extensively study the non-classical properties of the HHG process in a semiconductor for N>2. In the process, each emitted photon is a superposition of all frequencies in the spectrum, i.e., each photon is a comb so that each frequency component can be bunched and squeezed. The candidate will first develop and test entanglement and quantum correlations using the violation of Cauchy-Schwartz inequality. We will verify genuine multipartite entanglement of the photons in the time/frequency domain, by correspondingly measuring the longitudinal position as well as the frequency bandwidth. The approach will be further extended to verify multi-partite entanglement between even more optical modes.