Entangled photons from quantum dots in quantum information and communication

The photonic platform plays a pivotal role in the current development of quantum technologies, primarily of quantum communication. The goal of transferring quantum states of light across networks with extended travel distances and number of nodes is requiring advances—if not radically new approaches—in basic hardware components. The generation of entanglement is one of the crucial challenges, and the performance of current devices relying on probabilistic strategies can be improved upon. Quantum dots offer a way to generate polarization-entangled photon pairs relying on a deterministic physical mechanism. After many years of development, the technology is more mature and ready to compete with the state-of-the-art solutions.
This seminar will cover several aspects of the quantum dot-based entangled photon source, from fabrication to applications. First, it will address how to design a solid-state emitter to generate entangled photon pairs on demand. Special attention will be given to crucial challenges, such as efficiently collecting the photons and approaching near-ideal levels of entanglement.
The viability for quantum optics experiments is demonstrated in fundamental quantum information protocols, such as entanglement swapping and quantum teleportation. To showcase out-of-the-lab operation, I will present how quantum key distribution has been performed using a free-space optical link connecting the two buildings of the Department of Physics in the main campus of the Sapienza University.
Finally, I will give an outlook on the possible next steps in source development and on the applications of entangled photons in which a quantum-dot advantage could be leveraged over existing technologies.