The connection between the built-in non-linear metamaterial waveguide and resonant distributed fashion can provide absolute detection of photons with an error of less than one percent. A new concept for broadband single-photon detector in the microwave range physics described in a Preprint on arXiv.org.
Single-photon detectors — one of the key technologies of experimental quantum optics. Detection of photons in the ultraviolet, visible and infrared frequency range — well-established and routine technology: the devices are manufactured by many research groups and commercial companies and is readily available for purchase. As a rule, their principle of operation consists in the absorption of a photon sensitive semiconductor die or the superconducting nanowire. The resulting current pulse is recorded by electronic devices that gives information about the presence of the photon.
However, it is much more the case with photons of the microwave (or microwave) band, with frequencies from about 5 up to 20 GHz. Interest in the detection of such photons arises in the study of quantum systems operating at microwave frequencies: superconducting circuits, quantum dots and spin ensembles. As is known, the energy of a single photon is proportional to the frequency of the electromagnetic wave. For microwaves, the frequency of 4-5 orders of magnitude less than for IR and visible range. Therefore, check the response of the microwave photons is a highly non-trivial task.
Realization of quantum non-destructive measurements (CED) of a photon opens large perspectives for quantum electronics and quantum communications. In quantum mechanics, the term SOI refers to a strong projective measurement that leaves the system in the measured state. The photon absorption that occurs in traditional detectors, is not SOI — if a photon has ceased to exist, it is pointless to talk about the state of the light after the measurement.
However, it is possible to imagine a system that can react to the passing photon, while not destroying it, but only slightly changing its parameters. In this case we have information about the presence of a photon, and thus it continues its movement through the waveguide, and can carry information or interact with a quantum system. This is extremely useful for implementation of quantum communication and entanglement of remote quantum systems. But even in the visible range of physics for a long time could not show THEY. Only a few years ago appeared the first reports about successful CED photons reflected from an optical resonator. Read more about SOI photons of visible and infrared light can be read here.
Also there has been some progress on the way to SOI photons in the microwave range. Successful experiments (1,2) propose to detect the photon using conditional logical operation with a superconducting qubit. However, such prototypes are based on a temporary seizure of a photon in the resonator, which is extremely narrows the frequency band of a detected photon and also limits the quantum efficiency of the detector. This makes it impossible for large-scale use of such schemes. Thus, of particular importance is the development of the concept of a broadband, efficient and non-destructive detector of single photons in the microwave range.