Experimental Quantum Memory Applications and Demonstration of an Elementary Quantum Repeater Link with Entangled Light-Matter Interfaces

Entanglement is the essential feature of quantum mechanics. Remarkably, observers of two or more entangled particles will find correlations in their measurement results, that can not be explained by classical statistics. To make it a useful resource, particularly for scalable long-distance quantum communication, the heralded generation of entanglement between distant massive quantum systems is necessary. We report on the creation and analysis of heralded entanglement between spins of two single Rb-87 atoms trapped independently 20 meters apart. Our results illustrate the viability of an integral resource for quantum information science, as well as for fundamental tests of quantum mechanics.