Colloidal double quantum dots

Dan Oron, Physics of Complex Systems, Weizmann Institute, Rehovot, Israel

When considering the term 'quantum dot', usually an isolated emitter comes to mind. The advent of colloidal synthesis, however, now enables us to fabricate pairs of quantum dots with controlled coupling with them, a task which is extremely difficult to realize in other systems, such as self-assembled quantum dots. The energy landscape of these double quantum dots is tailored by the choice of material composition and size of both the optically active dots and the barrier layer separating them. Double quantum dots can be tailored to exhibit unique optical properties at the single-particle level, including two-color antibunching, controlled rapid fluctuations from an emitting state to a nearly 'dark' state, and a variety of nonlinear optical phenomena. Focusing on their function as two-color quantum emitters, the detailed relationship between intra-dot microscopic electronic phenomena and the optical properties of the entire structure will be discussed, along with pathways for achieving more complex optical function from such particles, including luminescence upconversion and sub-diffraction limited localization.