A group of physicists created quantum radar using entangled microwave photons, which are generated in superconducting non-linear system. Scientists experimentally showed the superiority of such a radar over the classical analogues. The work presented in the journal Science Advances.
The use of quantum resources allows not only to speed up computation (which is implemented in quantum computers), but also to improve other technologies such as detection of weak signals. The latter can be used in biology, medicine, Geology and even in space exploration. Microscopic quantum detectors, for example to record the weak magnetic fields that penetrate directly inside the experimental setup.
Quantum radars work a little differently. They give rise to quantum-correlated particles, which can be used to detect objects. In Anglophone literature this approach is called quantum operation (quantum illumination), it was first proposed in 2008, the American scientist Seth Lloyd. Quantum illumination is based on quantum entanglement between the particles (in the work of Lloyd it was about the photons), which allows the use of a single particle. The result of such a detector becomes non-invasive side of the object is almost impossible to say, there was a detection or not. This approach is very relevant in Biomedicine, is also interested in the military.
Since 2008, it was proposed several implementations of optical photons (terahertz frequencies), however the microwave range (gigahertz frequencies), which is actively used in quantum calculations, have not been studied from the point of view of quantum detection. Now physicists under the leadership of Professor Johaness Fink (Johannes Fink) created and tested the first prototype of a quantum of the microwave radar-based Josephson parametric oscillator, chilled to a few of millikelvins.
The group used the effect of parametric scattering in a superconducting system, which contained Dzhozefsonovskikh contacts. Such contacts are also used in superconducting quantum computers. The system was pumped by a microwave signal, which was born a pair of entangled photons, each of which went through different channels.