Towards Scalable Sources of Single and Entangled Photons based on Quantum Dots

by Rinaldo Trotta (Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Austria)

Thursday 3 Nov 2016, 16:00 → 18:00 Europe/Rome

Aula Conversi (Dipartimento di Fisica - Ed. G. Marconi)

The prospect of using the quantum nature of light for secure communication keeps spurring the search and investigation of suitable sources of single and entangled photons. Semiconductor quantum dots (QDs), also dubbed “artificial atoms”, are arguably one of the most attractive. They can generate single and entangled photons on demand, with high efficiency, and they are intrinsically compatible with current photonic-integration technologies. Unlike “natural atoms”, however, no two QDs are alike. This peculiarity is a major obstacle for quantum communication applications that require non-classical states of light with identical energies. In this talk, I will first introduce a novel class of semiconductor-piezoelectric devices [1, 2] in which different external perturbations are combined to reshape the electronic structure of any arbitrary QD [3, 4] so that single and polarization-entangled photons can be generated with unprecedented quality and speed [5, 6]. Then, I will show that full control over the QD in-plane strain tensor allows the energy of the entangled photons emitted by QDs to be precisely controlled without degrading the degree of entanglement [7, 8]. This opens the possibility to build up hybrid semiconductor-atomic interconnects, in which entangled photons from QDs are interfaced with clouds of natural atoms that behave as slow-light medium [9, 10]. To conclude, I will discuss how the developed technology can be exploited for the distribution of entanglement among the distant nodes of a quantum network made of electrically- controlled QD devices.