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Double-Occupancy Errors, Adiabaticity, and Entanglement of Spin-Qubits in Quantum Dots

John Schliemann·Daniel Loss·A. H. MacDonald
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Abstract

Quantum gates that temporarily increase singlet-triplet splitting in order to swap electronic spins in coupled quantum dots, lead inevitably to a finite double-occupancy probability for both dots. By solving the time-dependent Schrödinger equation for a coupled dot model, we demonstrate that this does not necessarily lead to quantum computation errors. Instead, the coupled dot ground state evolves quasi-adiabatically for typical system parameters so that the double-occupancy probability at the completion of swapping is negligibly small. We introduce a measure of entanglement which explicitly takes into account the possibilty of double occupancies and provides a necessary and sufficient criterion for entangled states.

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John Schliemann, Daniel Loss, A. H. MacDonald. 2000-09-06. Double-Occupancy Errors, Adiabaticity, and Entanglement of Spin-Qubits in Quantum Dots. https://doi.org/10.1103/physrevb.63.085311

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