Theory of superradiance by nano-array of quantum-well dots

The superradiance had been predicted by Dicke in 1954 theoretically [1] and observed in atomic and molecular systems experimentally [2]. In the recent experiments, the superradiance and superfluorescence by nano-structures of solid-state materials such as an ensemble of quantum dots were observed [3, 4]. The superradiance by solid-state materials has advantage for the application of devices as compared with that by other materials such as atoms and molecules. Our group also observed the superradiant behaviour of emissions from a semiconductor nano-rod as shown in Fig. 1 (a). This sample is a nano-array of quantum-well dots (QWDs) with the width of 3.25 nm and barrier layers with the width of 9 nm. The diameter of the rod is 80 nm. The number of QWDs is about ten. In order to clarify the mechanism of the new type of superradiance by solid-state materials, we constructed the full-quantum-mechanical theory of superradiance [5], in which theory, the fundamental equations of the superradiant photoluminescence were derived by the scheme of the semiconductor luminescence equations [6]. The important development of our theory is an introduction of a correlation between polarizations via a radiation field which is the origin of superradiance. Here we will clarify the characteristics of superradiant emissions from the nano-array of QWDs and prove that the superradiance by our sample of the nano-rod can be realized theoretically.