Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 92: Electronic Structure Theory
O 92.9: Talk
Thursday, March 20, 2025, 17:00–17:15, H25
Excitations in oxides: from bits to qubits — •Vijaya Begum-Hudde1, Yi-Ting Lee1, Barbara Jones2, and Andre Schleife1 — 1University of Illinois, Urbana-Champaign, USA. — 2IBM
Defects in materials are ubiquitous and may adversely affect their functional properties. Often the defects are confined to a small space, and defect embedding allows us to define an active space comprising of these defect states and to incorporate screening effects of the host material, enabling access to electronic properties with a high-level theory.
In this talk I will focus on the structural and electronic properties of near-surface vacancies in α-Al2O3 (0001) to investigate the influence of defects and hydration on the initiation and propagation of corrosion in this material. Utilizing first-principles calculations and quantum-defect embedding theory calculations, this study will analyse defect states and their ground- and excited-state properties. An active space is defined consisting of strongly localized states of the surface O vacany, and the remainder is treated as the environment. Next, an effective Hamiltonian is used for the active space that also includes the environment’s effective screening and is solved via full configuration interaction (FCI). Simulations are performed on a quantum computer with a Unitary coupled-cluster ansatz for the determination of ground- and excited-state properties. Error mitigation techniques will be demonstrated, reducing error due to the hardware noise and showing very good concordance with the FCI results within chemical accuracy.
We acknowledge funding by the IBM-Illinois Discovery Accelerator Institute.
Keywords: Near-surface defects; Excited-state properties; Defect embedding; Quantum computing