Scientists demonstrate quantum radar prototype

Science Daily  May 8, 2020 Instead of using conventional microwaves, an international team of researchers (Austria, UK. USA – MIT, Italy) entangled two groups of photons, which are called the ‘signal’ and ‘idler’ photons. The ‘signal’ photons are sent out towards the object of interest, whilst the ‘idler’ photons are measured in relative isolation, free from interference and noise. When the signal photons are reflected back, true entanglement between the signal and idler photons is lost, but a small amount of correlation survives, creating a signature or pattern that describes the existence or the absence of the target object — […]