Atomic phase coherence (quantum interference) in a multilevel atomic gas exhibits a number of interesting phenomena. Such an atomic quantum coherence effect can be generalized to a quantum-dot molecular dielectric. Two quantum dots form a quantum-dot molecule, which can be described by a three-level Λ-configuration model \(\{ |0\rangle ,|1\rangle ,|2\rangle \} \), i.e., the ground state of the molecule is the lower level |0〉 and the highly degenerate electronic states in the two quantum dots are the two upper levels \(|1\rangle ,|2\rangle \). The electromagnetic characteristics due to the |0〉–|1〉 transition can be controllably manipulated by a tunable gate voltage (control field) that drives the |2〉–|1〉 transition. When the gate voltage is switched on, the quantum-dot molecular state can evolve from one steady state (i.e., |0〉–|1〉 two-level dressed state) to another steady state (i.e., three-level coherent-population-trapping state). In this process, the electromagnetic characteristics of a quantum-dot mo...