Two-photon path-entangled states in multi-mode waveguides

We experimentally show that two-photon path-entangled states can be coherently manipulated by multi-mode interference in multi-mode waveguides. By measuring the output two-photon spatial correlation function versus the phase of the input state, we show that multi-mode waveguides perform as nearly-ideal multi-port beam splitters at the quantum level, creating a large variety of entangled and separable multi-path two-photon states.Comment: 4 pages, 4 figure

Radiative cascades in charged quantum dots

We measured, for the first time, two photon radiative cascades due to sequential recombination of quantum dot confined electron hole pairs in the presence of an additional spectator charge carrier. We identified direct, all optical cascades involving spin blockaded intermediate states, and indirect cascades, in which non radiative relaxation precedes the second recombination. Our measurements provide also spin dephasing rates of confined carriers.Comment: 4 pages, 3 figure

Single-photon synchronization with a room-temperature atomic quantum memory

Efficient synchronization of single photons that are compatible with narrowband atomic transitions is an outstanding challenge, which could prove essential for photonic quantum information processing. Here we report on the synchronization of independently-generated single photons using a room-temperature atomic quantum memory. The photon source and the memory are interconnected by fibers and employ the same ladder-level atomic scheme. We store and retrieve the heralded single photons with end-to-end efficiency of $\eta_\text{e2e}=25\%$ and final anti-bunching of $g^{(2)}_\text{h}=0.023$. Our synchronization process results in over tenfold increase in the photon-pair coincidence rate, reaching a rate of more than $1000$ detected synchronized photon pairs per second. The indistinguishability of the synchronized photons is verified by a Hong-Ou-Mandel interference measurement