Quantum radar and the generation of quantum microwaves
Superconducting electronic devices, similar to those used in quantum computers by Google and IBM, can be used to generate microwaves. Such devices operate at very low temperatures (~0.1 Kelvin), are shielded from all interference, and are therefore described by the laws of quantum mechanics. The generated microwave radiation may, hence, also inherit quantum mechanical properties. It is thus fundamentally different from conventionally generated electromagnetic waves, for example, from radiation produced by an alternating current in a radio transmitter antenna, from the light of a laser, or from the thermal radiation of a light bulb.
Together with experimentalists in Paris (CEA-Saclay), we have shown in recent years that so-called Josephson-Photonics devices can operate in such a way, that
- the individual photons are ordered (single photon source)
- several photons are generated at once (pair and multiplet sources)
- or quantum mechanically entangled radiation is emitted at two frequencies.
Light or microwaves with the mentioned entanglement properties can be used to increase sensitivity in the observation of an object. We are exploring in collaboration with the DLR Institute of High Frequency Technology and Radar Systems the feasibility of using these concepts in a quantum radar. In such a system, one of the generated entangled signals is transmitted to the observed object and the reflected signal is detected together with the second (retained) signal in a correlation measurement. The influence of perturbing spurious radiation is minimized by this method, which should give quantum radar systems a fundamental advantage over any classical radar system. We are pursuing first fundamental studies on the road towards viable technological application.