On the front cover of Advanced Quantum Technologies with a novel concept for remote quantum phase estimation.
CNR-INO researchers led by Marco Bellini and Alessandro Zavatta demonstrated a new scheme for the remote phase estimation of a distant, and possibly delicate, sample (the cell in the background of this pictorial representation) with a sensitivity that only depends on the intensity of light that never interacted with it. This is made possible by the extreme fragility of the entanglement produced between two laser pulses (in the foreground) via coherent addition of a single photon, which strongly depends on the relative phase between two single-photon-level pulses in the distant heralding station, where the sample is placed.