Exploiting quantum phenomena for sensitive photonic terahertz detection

The recently unveiled in-plane photoelectric effect is a quantum phenomenon that opens the doors to a new type of photonic terahertz detectors which utilize quantum transitions within a well-conducting, degenerate 2D electron system (2DES). This effect describes the absorption of photons by electrons at an artificially created, gate-voltage- tunable potential step within the plane of a 2DES, which leads to an electron flow from the high to the low density region of a much higher magnitude than expected from previously known, classical mechanisms. Detectors exploiting this effect were called photoelectric tunable step (PETS) terahertz detectors. The features of the in-plane photoelectric effect are pointed out and compared with the conventional three-dimensional photoelectric effect. The implications of the existence of the in-plane photoelectric effect on the understanding of light-matter interaction within the traditional pictures of classical and quantum physics are discussed. Current trends in the area of PETS detector development are reviewed and opportunities for new photonic terahertz detectors are highlighted, with a focus on practical applications in terahertz technology.