Researchers at the University of Innsbruck, funded by the US Army, achieved a record for the transfer of quantum entanglement between matter and light -- a distance of 50 kilometers was covered using fiber optic cables. Researchers said this brings the quantum internet a step closer. In a nonlinear crystal illuminated by a strong laser the photon wavelength was converted to the optimal value for long-distance travel.
The image depicts a schematic of terahertz (THz) heterodyne detection with graphene. In this, two THz waves (red) are coupled into graphene, where they are combined or mixed. One of the waves is a high intensity signal generated by a local THz light source (i.e. a local oscillator), at a known THz frequency. The other signal is a faint THz wave that mimics the waves coming from space.