RESUMEN
The distribution of entanglement via satellite links will drastically extend the reach of quantum networks. Highly efficient entangled photon sources are an essential requirement towards overcoming high channel loss and achieving practical transmission rates in long-distance satellite downlinks. Here we report on an ultrabright entangled photon source that is optimized for long-distance free-space transmission. It operates in a wavelength range that is efficiently detected with space-ready single photon avalanche diodes (Si-SPADs), and readily provides pair emission rates that exceed the detector bandwidth (i.e., the temporal resolution). To overcome this limitation, we demultiplex the photon flux into wavelength channels that can be handled by current single photon detector technology. This is achieved efficiently by using the spectral correlations due to hyper-entanglement in polarization and frequency as an auxiliary resource. Combined with recent demonstrations of space-proof source prototypes, these results pave the way to a broadband long-distance entanglement distribution network based on satellites.
RESUMEN
We unveil different regimes for the interaction between two orthogonally polarized soliton-like beams in a colloidal suspension of nanoparticles with positive polarizability. The interaction is always attractive. However, it noticeably changes as a function of the angle and the power distribution between the input beams. For small angles, both interacting solitons fuse into a single entity, whose propagation direction can be continuously steered. As the interaction angle increases, the resulting self-collimated beam can be practically switched between two positions when the power imbalance between the beams is changed. For interaction angles larger than â¼10°, the result is no longer a single emerging soliton when the input power is balanced between the two beams.