Towards Compact Wavefunctions from Quantum-Selected Configuration Interaction

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• Tim Weaving and Alexis Ralli, UCL
• Wednesday 03 December 2025, 12:30-14:00
• U202 Meeting room, Department of Chemistry, Cambridge.

If you have a question about this talk, please contact Chiara Leadbeater.

We present a hybrid quantum-classical algorithm that leverages Hamiltonian time evolution to guide subspace expansion in the Quantum-Selected Configuration Interaction (QSCI) framework, with multireference perturbation theory accounting for missed correlation outside the configuration subspace. Using 42 qubits of an IQM superconducting device, we compute the potential energy curve of SiH₄ (6-31G basis) under a stretching of the Si-H bond length and benchmark against Heatbath CI (HCI). While previous QSCI works failed to produce compact wavefunctions, at stretched geometries we come close to HCI -level compactness, marking progress towards surpassing this formidable target.

This talk is part of the Quantum Computing for Quantum Chemistry series.

This talk is included in these lists:

• Quantum Computing for Quantum Chemistry
• U202 Meeting room, Department of Chemistry, Cambridge

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