Qumode-Based Variational Quantum Eigensolver for Molecular Excited States

作者：Rishab Dutta, Cameron Cianci, Alexander V. Soudackov, Yuchen Wang, C. F. Xu, David A. Mazziotti, Lea F. Santos, Víctor S. Batista · 发表于：Journal of Chemical Theory and Computation · 年份：2026 · DOI：10.1021/acs.jctc.5c01494 · 被引用次数：3 · 研究领域：Photonic and Optical Devices、Mechanical and Optical Resonators、Semiconductor Lasers and Optical Devices

We introduce the qumode subspace variational quantum eigensolver (QSS-VQE), a hybrid quantum-classical algorithm for computing molecular excited states using the Fock basis of bosonic qumodes in circuit quantum electrodynamics (cQED) devices. This approach harnesses the native universal gate sets of qubit-qumode architectures to construct highly expressive variational ansatze, offering potential advantages over conventional qubit-based methods. In QSS-VQE, the electronic structure Hamiltonian is first mapped to a qubit representation and subsequently embedded into the Fock space of bosonic qumodes, enabling efficient state preparation and reduced quantum resource requirements. We demonstrate the performance of QSS-VQE through simulations of molecular excited states, including dihydrogen and a conical intersection in cytosine. Additionally, we explore a bosonic model Hamiltonian to assess the expressivity of qumode gates, identifying regimes where qumode-based implementations outperform purely qubit-based approaches. These results highlight the promise of leveraging bosonic degrees of freedom for enhanced quantum simulation of complex molecular systems.