Hot Carrier Ground States in Coupled Quantum Dots

Epitaxially grown quantum dots are promising systems for semiconductor quantum science and technology because of their demonstrated support of optically addressable quantum states, widely tunable quantum properties, and ease of integration with conventional electronics. Coupling quantum dots enhances that functionality, for example, by providing the means to tune spin-spin interactions via electric fields at tunnel resonances. Ground state charge and spin configurations in coupled dots have been identified routinely by their distinct tunnel resonance features and their fine structure in electric field dispersed spectra, providing the basis for identifying novel states and interactions. Observations of unusual splittings, tunnel resonance features, and fine structure are reported and characterized by photoluminescence and magneto-optical spectroscopy. Our analysis of the electric field dispersed spectra, emission polarization, and g-factors indicates the formation of spin exchange stabilized hot carrier states. The observation of these states provides fresh opportunities to manipulate spin-spin interaction and therefore state initialization in quantum information processing or sensing.