FABRICATION OF ULTRA-COMPACT SOURCES OF ENTANGLED PHOTON PAIRS BASED ON 2D MATERIALS

Work package:
Entangled photon pairs are fundamental to quantum science. They enhance our understanding of quantum non-locality through the violation of Bell inequalities and play a vital role in modern quantum technologies for computing, communication, and metrology. Developing ultra-compact entangled photon sources is essential for the miniaturization of quantum photonic devices. 2D van der Waals materials recently developed address this challenge by enabling efficient photon-pair generation and monolithic on-chip integration with nanophotonic circuits [1–6]. The goal of this project is therefore to fabricate new ultra-compact sources of polarization-entangled photon pairs based on 2D semiconductor materials. The photon pairs will be generated via parametric processes in a non-centrosymmetric nanocrystal with a thickness of a few tens of nanometers, more than four orders of magnitude thinner than the millimeter-scale materials currently in use. Such extreme thinness eliminates phase-matching constraints, resulting in photon-pair generation across a very broad spectral band that encompasses the optical telecommunications range. The main target of this internship is the fabrication of these innovative sources based on a large number of stacked nano-layers following similar approaches as in references [4,5]. The main characterization tools will be AFM and Second Harmonic Generation measurement techniques. If successful, the student could be involved at the end of the project on the measurement and optimization of the characteristics of these new sources of entangled photons. The study's results will be shared with potential users who have shown interest in this new technology (French Space Agency CNES, Airbus Defense&Space, Thales Alenia Space). The OPTO team possesses the expertise in both the fabrication of structures based on 2D materials and the characterization of the optical properties of novel 2D materials. The proposed study builds upon the OPTO team's expertise - developed over more than a decade - in fabricating van der Waals heterostructures based on 2D materials (such as MoS2, WSe2, and hBN) [6–9]. Devices based on 2D materials for generating entangled photon pairs will be fabricated at the LPCNO’s dedicated @Exfolab facility, which houses the necessary equipment (four exfoliation/transfer systems, two atomic force microscopes, furnaces, photolithography tools, etc.) and dedicated in-situ characterization instruments (Raman, absorption, luminescence, etc.). Optical characterization (micro-reflectivity and luminescence measurements) could be performed using the OPTO team’s state-of-the-art optical spectroscopy equipment. Measurements involving entangled photons (g2 autocorrelation and tomography) will be carried out on a dedicated setup recently developed by the OPTO team.