Expérimental
Quantum information science and imaging technologies reach some bottleneck due to limited scalability of non-classical sources. Future breakthroughs will rely on high production rate of various quantum states in scalable platforms. Generally, multipartite entanglement with N>2 suitable for quantum applications is difficult to achieve because of the low efficiency of the traditional schemes. 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. The Bell-like inequalities will therefore be generalized to witness entanglement between more than three mixed quantum states.