Sub-shot-noise manipulation of light using semiconductor emitters and receivers

We describe an amplifying system using a photodiode and a light emitting diode, which is able to measure and to ``recreate'' the quantum statistics of the intensity of a light beam. This system acts therefore as a nonclassical ``quantum optical repeater.'' The overall information transfer is improved by a factor of 1.8 compared to a classical device, while the ideal quantum value would be 2, and the correlation between the signal and meter outputs is 1.2 dB below the shot-noise limit. We also demonstrate the use of this device for both detecting and recreating an input squeezed state.