Molecular orbital calculations of two-electron states for P-donor solid-state spin qubits

Kettle, L. M., Goan, H. S. and Smith, S. C. (2006) Molecular orbital calculations of two-electron states for P-donor solid-state spin qubits. Physical Review B, 73 11: 115205-1-115205-14. doi:10.1103/PhysRevB.73.115205

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Author Kettle, L. M.
Goan, H. S.
Smith, S. C.
Title Molecular orbital calculations of two-electron states for P-donor solid-state spin qubits
Journal name Physical Review B   Check publisher's open access policy
ISSN 1098-0121
Publication date 2006-03-15
Sub-type Article (original research)
DOI 10.1103/PhysRevB.73.115205
Open Access Status File (Publisher version)
Volume 73
Issue 11
Start page 115205-1
End page 115205-14
Total pages 14
Place of publication New York
Publisher The American Physical Society
Language eng
Abstract We theoretically study the Hilbert space structure of two neighboring P-donor electrons in silicon-based quantum computer architectures. To use electron spins as qubits, a crucial condition is the isolation of the electron spins from their environment, including the electronic orbital degrees of freedom. We provide detailed electronic structure calculations of both the single donor electron wave function and the two-electron pair wave function. We adopted a molecular orbital method for the two-electron problem, forming a basis with the calculated single donor electron orbitals. Our two-electron basis contains many singlet and triplet orbital excited states, in addition to the two simple ground state singlet and triplet orbitals usually used in the Heitler-London approximation to describe the two-electron donor pair wave function. We determined the excitation spectrum of the two-donor system, and study its dependence on strain, lattice position, and interdonor separation. This allows us to determine how isolated the ground state singlet and triplet orbitals are from the rest of the excited state Hilbert space. In addition to calculating the energy spectrum, we are also able to evaluate the exchange coupling between the two donor electrons, and the double occupancy probability that both electrons will reside on the same P donor. These two quantities are very important for logical operations in solid-state quantum computing devices, as a large exchange coupling achieves faster gating times, while the magnitude of the double occupancy probability can affect the error rate.
Keyword Physics, Condensed Matter
Kane Quantum Computer
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Chemistry and Molecular Biosciences
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 11 times in Scopus Article | Citations
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Created: Mon, 13 Aug 2007, 16:06:29 EST