Coherent state monitoring in quantum dots

We study the dynamics of excitonic states in dimer and trimer arrangements of colloidal quantum dots using a density-matrix approach. The dots are coupled via a dipole-dipole interaction akin to the Forster mechanism. Coherent oscillations of tuned donor dots are shown to appear as plateaus in the acceptor dot, and therefore in its optical response. This behavior provides one with an interesting and unique handle to monitor the quantum state of the dimer, an "eavesdroping arrangement." A trimer cluster in a symmetrical loop shows steady states in a shorter characteristic time than the typical radiative lifetime of the dots. Breaking the symmetry of the loop results again in damping oscillatory states in the donor dots and plateaus in the eavesdropping/acceptor dot. The use of realistic parameters allows direct comparison with recent experiments and indicates that coherent-state monitoring is possible in real experiments.