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

## TL;DR

This paper explores how to perform quantum chemistry simulations of lithium superoxide dimer rearrangement on noisy quantum devices by reducing qubit requirements through active space limitation and using variational algorithms, showing promising results with some hardware limitations.

## Contribution

It introduces a method to reduce qubit count in quantum chemistry simulations by limiting active space and demonstrates its effectiveness on noisy quantum devices for lithium superoxide dimer.

## Key findings

- Quantum simulators can approximate classical energy values with limited active space.
- Quantum hardware underestimates energies despite error mitigation.
- Active space reduction enables feasible quantum chemistry calculations on NISQ 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 ans\"atze 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.

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Source: https://tomesphere.com/paper/1906.10675