12 papers
Analytical Nuclear Gradients and Hessians on Quantum Hardware via Orbital-Optimized VQE with Error Mitigation
Renato Olarte Hernandez, Karl Michael Ziems, Erik Kjellgren +3
Nuclear gradients and Hessians are fundamental quantities in computational chemistry, essential for a wide range of applications including geometry optimization, vibrational spectr…
Resource-efficient energy-based operator selection in fermionic ADAPT-VQE via exact Hamiltonian transformation
Emanuele Rossi, Erik Rosendahl Kjellgren, Artur F. Izmaylov +3
The energy-based approach to operator selection in ADAPT-VQE relies on reconstructing the one-parameter energy landscape for each operator in the pool. In fermionic implementations…
Orbital-optimized spin-adapted multistate contracted VQE for excited states and properties on quantum hardware
Erik Rosendahl Kjellgren, Karl Michael Ziems, Peter Reinholdt +3
We introduce the orbital-optimized multistate contracted variational quantum eigensolver (oo-MC-VQE) method with spin-adapted operators for the computation of ground and excited st…
A Lanczos-based algorithm for sum-over-states calculations of NMR spin--spin coupling constants at the RPA level of theory: The Fermi-contact term
Sarah L. V. Zahn, Luna Zamok, Sonia Coriani +1
The analysis of nuclear magnetic resonance parameters, such as the indirect nuclear spin-spin coupling constants, in terms of contributions from localised molecular orbitals is a c…
Quantum error mitigation using energy sampling and extrapolation enhanced Clifford data regression
Zhongqi Zhao, Erik Rosendahl Kjellgren, Sonia Coriani +3
Error mitigation is essential for the practical implementation of quantum algorithms on noisy intermediate-scale quantum (NISQ) devices. This work explores and extends Clifford Dat…
Cost-effective scalable quantum error mitigation for tiled Ansätze
Oskar Graulund Lentz Rasmussen, Erik Kjellgren, Peter Reinholdt +4
We introduce a cost-effective quantum error mitigation technique that builds upon the recent Ansatz-based gate and readout error mitigation method (M0). The technique, tiled M0, le…