Ricerc@Sapienza

The quantum network, an infrastructure that supports intrinsically safe communication and connects quantum computers, is arguably the vision from the second quantum revolution which is closest to realization. The accomplishment of this enterprise requires quantum memory devices and on-demand single photon sources. These building blocks constitute the so-called quantum node. A quantum memory should be able to faithfully store flying qubits and release them on-demand, while a single photon source should emit on-demand single photons and, potentially, entangled photon pairs. To build quantum nodes, an approach which combines different quantum systems is likely to be the most rewarding. Semiconductor quantum dots, also dubbed artificial atoms, are emerging as near optimal sources of non-classical light, since they can emit single and polarization-entangled photon pairs with very high efficiency and at high repetition rate. On the other hand, alkali vapor cells have gained a lot of attention in the last years due to their capability of storing qubits even at room temperature without the need of sophisticated techniques. Moreover, it has been shown that they can also work as delay lines and spectral filters for flying qubits. Despite pioneering experiments in this field, a detailed description focused on the interconnection between these two physical systems is still lacking in the literature. In this project, a systematic study of this hybrid artificial-natural atomic system will be performed. GaAs quantum dots grown by droplet etching and integrated on a strain-tunable device will be used as sources of single and entangled photons in a micro-photoluminescence setup. In parallel, a 87Rb vapor cell will be investigated as a prospective quantum memory. Since our group's knowledge regarding the quantum dot topic is well established, emphasis will be devoted to optically characterize the vapor cell and test its suitability as quantum interconnect for quantum dot photons.