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Updated: Jun 30, 2025
08:04
Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
8.4K
Folded Spectrum VQE: A Quantum Computing Method for the Calculation of Molecular Excited States
Lila Cadi Tazi1,2, Alex J W Thom2
1École Normale Supérieure Paris-Saclay, Université Paris-Saclay, Gif-sur-Yvette 91190, France.
Journal of Chemical Theory and Computation
|March 16, 2024
Summary
This study introduces the folded spectrum-VQE method to compute molecular excited states using quantum computing. The approach achieves chemical accuracy for small molecules, even with error mitigation on noisy quantum simulators.
Area of Science:
- Quantum Computing
- Computational Chemistry
- Quantum Algorithms
Background:
- Quantum computing offers novel approaches for quantum chemistry, with algorithms like VQE computing ground-state energies.
- Noisy intermediate-scale quantum devices necessitate hybrid algorithms for practical applications.
Purpose of the Study:
- Investigate the folded spectrum (FS) method as an extension of VQE for computing molecular excited states.
- Enable direct computation of excited states near a target energy using existing VQE circuits.
Main Methods:
- Implemented the folded spectrum (FS) method with the variational quantum eigensolver (VQE).
- Utilized Pauli grouping to reduce the computational cost associated with the squared Hamiltonian.
- Applied quantum error mitigation techniques to enhance accuracy on noisy simulators.
Main Results:
- Successfully computed all electronic excited states for H2 and LiH molecules with chemical accuracy on ideal quantum simulators.
- Demonstrated improved energy accuracy on noisy simulators using quantum error mitigation.
Conclusions:
- The FS-VQE method is a viable extension of VQE for calculating molecular excited states.
- Pauli grouping significantly reduces computational overhead, making the method more scalable.
- Quantum error mitigation is crucial for achieving accurate results on current quantum hardware.
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