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arXiv · 2602.20270

Quantum algorithm for simulating resonant inelastic X-ray scattering in battery materials

Ignacio Loaiza·Alexander Kunitsa·Stepan Fomichev·Danial Motlagh·Diksha Dhawan·Soran Jahangiri·Juliane Holst Fuglsbjerg·Artur F. Izmaylov·Nathan Wiebe·Yaser Abu-Lebdeh·Juan Miguel Arrazola·Alain Delgado
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Abstract

Resonant inelastic X-ray scattering (RIXS) is the workhorse experimental technique for probing the structural degradation of higher-capacity cathode materials. However, the interpretation of experimental spectra is challenging due to the lack of accurate simulations. In this work, we propose a quantum algorithm for simulating the RIXS spectrum of molecular clusters hypothesized to form in Li-excess cathodes. The algorithm uses quantum phase estimation to sample the spectrum from a state encoding the scattering transition amplitudes of the cluster valence excitations. We prepare this state in the quantum computer using a block-encoding of the dipole operator and quantum signal processing to implement the Green's function propagator over intermediate core-excited states. To showcase the algorithm, we use a model cluster proposed in recent experimental works consisting of an oxygen dimer bonded to a manganese atom. Using the PennyLane software platform, we report resource estimation for simulating RIXS spectra for chemically motivated active spaces of increasing sizes. For a classically challenging active space with 20 orbitals, the algorithm requires $2.0 \times 10^{10}$ Toffoli gates and $414$ logical qubits.

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Ignacio Loaiza, Alexander Kunitsa, Stepan Fomichev, Danial Motlagh, Diksha Dhawan, Soran Jahangiri, Juliane Holst Fuglsbjerg, Artur F. Izmaylov, Nathan Wiebe, Yaser Abu-Lebdeh, Juan Miguel Arrazola, Alain Delgado. 2026-02-23. Quantum algorithm for simulating resonant inelastic X-ray scattering in battery materials. https://arxiv.org/abs/2602.20270

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