TURKOV Vadim St.Petersburg National Research University of Information Technologies, Mechanics and Optics

A Theory of Low-temperature Stationary Photoluminescence of a Quantum-dot Molecule

Co-authors KRUCHININ Stanislav, RUKHLENKO Ivan, BAIMURATOV Anvar, LEONOV Mikhail, GUN'KO Yurii, BARANOV Aleksander, FEDOROV Anatoly

We have developed a theory of low-temperature, stationary photoluminescence from a pair of spherical quantum dots coupled by the Coulomb interaction in a quantum-dot molecule. The interdot Coulomb interaction can lead to both the incoherent and coherent energy transfers in the closely packed assemblies of quantum dots, just as it does in atomic and molecular systems. In this work we present a theory on the secondary emission from a pair of coherently coupled quantum dots and analyzing the manifestations of coherence effects in the photoluminescence spectra The lowest-energy electron-hole-pair states of the dots were assumed to be nearly resonant and characterized by low decay and dephasing rates. The coherent coupling of the quantum dots under these conditions was shown to manifest itself in the molecule's photoluminescence spectrum as a pair of peaks, the intensities and spectral positions of which are determined by the geometry (quantum dot sizes and distance between them) and material of the nanocrystals, as well as by the rates of the energy and phase relaxations of their electronic subsystems. We also derived an expression for the photoluminescence differential cross section, which is useful for interpreting and analyzing the secondary emission spectra of coherently coupled quantum dots. We illustrate the results obtained by considering two identical quantum dots made from the cubic modification of CdSe and InSb.