In summary, 4PHOTON project pursues the following goals:
1. From the scientific and technological side to fabricate single and entangled photon sources for quantum information and quantum communication exploring innovative fabrication methods and physical properties of low dimensionality materials
2. The educational goal to provide a multidisciplinary training program for a new generation of European researchers capable to develop Quantum Technologies to the level of real-world applications.
The scientific program focused on the development of four key scientific and technological goals (KST)
KST1: Realization of on demand single and entangled photon sources relying on as-grown, droplet epitaxy, symmetric QDs
Quantum cryptography and optical computation schemes are based on the manipulation of indistinguishable and entangled photons. Fundamental understanding and consequent unprecedented control of the growth process of semiconductor quantum dots, also embedded in nanowires, has been obtained. The outcome has been the ability to fabricate GaAs quantum dots and telecom O-Band entangled photon emitters quantum photonics and quantum cryptography.
KST2: Non-classical light storage for quantum optical circuits using a deterministic single-photon sources
A quantum network consists of a coherent quantum system at each node, with each node coupled together via single photons, which must be created on demand, stored and later recreated. 4PHOTON young researchers were able to develop extremely low-noise single photon sources based on droplet epitaxy growth techniques, able to match the stringent requests for working quantum networks.
KST3: Nano-engineering of quantum confined carrier states and spin
A new class of materials, characterized by a reduced dimensionality, are now on the spot for advanced quantum technological applications. The optical and electrical properties of quantum emitters in 2D materials (e.g. MoS2) have to be widely tunable and controllable for realistic device applications. Several advances, in the understanding of fundamental properties of the excitonic emission of the mono-multilayers, also coupled to dielectric antennas, have been obtained within the project.
KST4: Fabrication of quantum integrated circuits and quantum photonic devices on silicon
An innovative path towards the integration of high efficiency quantum emitters on silicon has been studied by 4PHOTON network young researchers. It consists in the fabrication, by dewetting process, of nanoscale Mie dielectric resonators. These structures would provide self-assembled photonic cavities for the enhancement of photon extraction from quantum emitters embedded in the cavity itself.
The young researchers were trained, through research activities also performed during secondments and formal training. During the project the network organized three schools Introduction to 1- Quantum Information; 2- Quantum Dots: from growth to fundamental properties; 3- Nano Photonics and three workshops 1 - Droplet based Quantum Nanostructures and Devices; 2- Quantum Optical Devices and Circuits; 3- Quantum Optical Devices and Circuits. The final 4PHOTON conference will take place within the framework of the 8th Semiconnano web workshop.
In addition to excellent research training, ESRs received training in complementary skills through network-wide training (1- Becoming excellent and impactful communicators; 2- Collaborations across borders Quantum Communication Technology; 3- Researchers of the future) provided by Think Ahead (led by Sandrine Soubes). The ESRs YouTube videos explaining their research to non-specialists are available on the 4photon web site (www.4photon.unimib.it).