Interplay of exchange and superexchange in triple quantum dots

Abstract

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. Taking advantage of this opportunity requires a deeper understanding of how to control superexchange interactions in these systems. Here, we consider a triple-dot system arranged in linear and triangular geometries. We use configuration interaction calculations to investigate the interplay of superexchange and nearest-neighbor exchange interactions as the location, detuning, and electron number of the mediating dot are varied. We show that superexchange processes strongly enhance and increase the range of the net spin-spin exchange 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.

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Cited by in corpus (9)

• Semiconductor Spin Qubits
• Exchange coupling in a linear chain of three quantum-dot spin qubits in silicon
• High-precision real-space simulation of electrostatically-confined few-electron states
• Theory on electron-phonon spin dehphasing in GaAs multi-electron double quantum dots
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• Dressed basis sets for the modeling of exchange interactions in double quantum dots
• Exploring Entanglement Spectrum and Phase Diagram in multi-electron Quantum Dot Chains
• Negative exchange interaction in Si quantum dot arrays via valley-phase induced ${\mathbb{Z}}_2$ gauge field