Double-occupancy errors, adiabaticity, and entanglement of spin qubits in quantum dots

John Schliemann, Daniel Loss, and A. H. MacDonald
Phys. Rev. B 63, 085311 – Published 2 February 2001
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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 quasiadiabatically for typical system parameters so that the double-occupancy probability at the completion of swapping is negligibly small. We introduce a measure of entanglement that explicitly takes into account the possibilty of double occupancies and provides a necessary and sufficient criterion for entangled states.

  • Received 6 September 2000

DOI:https://doi.org/10.1103/PhysRevB.63.085311

©2001 American Physical Society

Authors & Affiliations

John Schliemann1,2, Daniel Loss3, and A. H. MacDonald1,2

  • 1Department of Physics, Indiana University, Bloomington, Indiana 47405
  • 2Department of Physics, The University of Texas, Austin, Texas 78712
  • 3Department of Physics and Astronomy, University of Basel, Klingelbergstraße 82, CH-4056 Basel, Switzerland

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Issue

Vol. 63, Iss. 8 — 15 February 2001

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