Interplay of exchange and superexchange in triple quantum dots

Recent experiments on semiconductor quantum dots have demonstrated the ability to utilize a large quantum dot to mediate superexchange interactions and generate entanglement between distant spins. This opens up a possible mechanism for selectively coupling pairs of remote spins in a larger network of quantum dots. We describe our theoretical efforts to understand the controllability of superexchange interactions in these systems. We focus on a triple-dot system arranged in linear and triangular geometries and use configuration interaction calculations to investigate the interplay of superexchange and nearest-neighbor exchange interactions. We show that superexchange processes strongly enhance the range of the net spin-spin coupling as the dots approach a linear configuration. Furthermore, we show that the strength of the exchange interaction depends sensitively on the number of electrons in the mediator. Our results can be used as a guide to assist further experimental efforts towards scaling up to larger, two-dimensional quantum dot arrays.