Interacting holes in Si and Ge double quantum dots: From a multiband approach to an effective-spin picture

Andrea Secchi, Laura Bellentani, Andrea Bertoni, and Filippo Troiani
Phys. Rev. B 104, 035302 – Published 12 July 2021

Abstract

The states of two electrons in tunnel-coupled semiconductor quantum dots can be effectively described in terms of a two-spin Hamiltonian with an isotropic Heisenberg interaction. A similar description needs to be generalized in the case of holes due to their multiband character and spin-orbit coupling, which mixes orbital and spin degrees of freedom and splits j=3/2 and j=1/2 multiplets. Here we investigate two-hole states in prototypical coupled Si and Ge quantum dots via different theoretical approaches. Multiband k·p and configuration-interaction calculations are combined with entanglement measures in order to thoroughly characterize the two-hole states in terms of band mixing and justify the introduction of an effective spin representation, which we analytically derive a from generalized Hubbard model. We find that, in the weak interdot regime, the ground state and first excited multiplet of the two-hole system display—unlike their electronic counterparts—a high degree of J mixing, even in the limit of purely heavy-hole states. The light-hole component additionally induces M mixing and a weak coupling between spinors characterized by different permutational symmetries.

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  • Received 20 April 2021
  • Revised 30 June 2021
  • Accepted 30 June 2021

DOI:https://doi.org/10.1103/PhysRevB.104.035302

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsQuantum Information, Science & Technology

Authors & Affiliations

Andrea Secchi*, Laura Bellentani, Andrea Bertoni, and Filippo Troiani

  • Centro S3, CNR-Istituto di Nanoscienze, I-41125 Modena, Italy

  • *andrea.secchi@nano.cnr.it

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Issue

Vol. 104, Iss. 3 — 15 July 2021

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