Quantum radar and quantum communication are new fields in which information is transmitted between two or more points by using single photons, referring to their quantum state (e.g., polarization, or phase) of each photon separately. In this way information can be transmitted fully encrypted without the possibility of eavesdropping. Moreover, if there is an eavesdropper on the way, this can be discovered by using the basic laws of quantum mechanics. As a result, quantum communication systems are already widely used today by a number of business and military entities. Quantum radar systems are yet to be developed and proven. One of the major problems in quantum radar and communication today, is the need to deploy high quality optical fibers between the parties, as they are required to transmit signals of individual photons with low attenuation. It is also possible to use satellites, but still, because the information is transmitted in photons at an optical wavelength, there is a strong attenuation in the atmosphere and the range is very limited. Therefore, it is no secret that many parties are interested in developing quantum communication and quantum radar systems at microwave frequencies (e.g. 10-100 GHz), in which the atmospheric attenuation is much smaller and can, theoretically, allow the establishment of a quantum communication channel even without the use of fiber – i.e. in free space. However, the main reason that no such technology has been developed so far is that there are no amplifiers and detectors of individual microwave photons that operate at room temperature (or even close to room temperature). The developed technology aims to solve this by using solid-state Maser (Microwave Amplifier by Stimulated Emission of Radiation) based on nitrogen-vacancies (NV) centers in diamond. The developed prototype is actually a quantum amplifier device that uses the energy levels in the solid state of the diamond to amplify the signal of the microwave photons, without adding almost any background noise, even when operating at room temperature.
- Room temperature operation – no need for cryogenic cooling, larger bandwidth of operation, larger gain, higher power saturation, better heat dissipation