Computational Investigations of the Lithium Superoxide Dimer Rearrangement on Noisy Quantum Devices

Abstract

Currently available noisy intermediate-scale quantum (NISQ) devices are limited by the number of qubits that can be used for quantum chemistry calculations on molecules. We show herein that the number of qubits required for simulations on a quantum computer can be reduced by limiting the number of orbitals in the active space. Thus, we have utilized ansätze that approximate exact classical matrix eigenvalue decomposition methods (Full Configuration Interaction). Such methods are appropriate for computations with the Variational Quantum Eigensolver algorithm to perform computational investigations on the rearrangement of the lithium superoxide dimer with both quantum simulators and quantum devices. These results demonstrate that, even with a limited orbital active space, quantum simulators are capable of obtaining energy values that are similar to the exact ones. However, calculations on quantum hardware underestimate energies even after the application of readout error mitigation.

Solving nonlinear differential equations with differentiable quantum circuits

“…The paradigmatic hybrid algorithm corresponds to the variational quantum eigensolver (VQE) [42,43], where a quantum computer is used to prepare parametrized quantum states and measure their energy, while classical optimization is used for finding the best variational parameters. This strategy enables quantum calculations with relatively noisy devices, and allows for numerous advances from the experimental [44][45][46][47][48][49][50][51][52] and theoretical [53][54][55][56][57][58][59][60][61][62][63][64][65][66] perspectives.…”

Qubit-efficient encoding scheme for quantum simulations of electronic structure

“…The time cost of quantum simulation can scale polynomially with system size as compared to exponentially using classical computers [4,14]. With such polynomial time scaling of quantum algorithms and as quantum hardware is getting increasingly reliable and scalable, quantum simulation of physical systems has drawn great attention of researchers since classically intractable ab-initio calculations of proteins and materials could one day be realized using quantum bits (qubits) [3,[24][25][26][27][28][29]. * goan@phys.ntu.edu.tw A significant challenge of quantum simulations is the quantum resources required to reliably perform quantum algorithms.…”

Towards Accurate Description of Chemical Reaction Energetics by Using Variational Quantum Eigensolver: A Case Study of the C2v Quasi-Reaction Pathway of Beryllium Insertion to H2 Molecule

“…Proof-of-principle demonstrations on quantum devices were also reported. [46][47][48][49][50] Recent reviews in this field can be found elsewhere. [51][52][53][54][55] From the viewpoint of chemistry, we emphasize that most of problems in chemistry focus on the energy differences between two or larger number of electronic states or geometries, rather than the total energies themselves.…”