A Quantum-compute Algorithm for Exact Laser-driven Electron Dynamics in Molecules

TL;DR

This paper demonstrates the use of quantum computing algorithms to simulate laser-driven electron dynamics in molecules, achieving results comparable to classical methods with polynomial scaling, promising advances in molecular quantum simulations.

Contribution

It introduces quantum algorithms for simulating electron dynamics in molecules, including non-Hermitian operators, with polynomial scaling, advancing quantum computational chemistry.

Findings

Quantum algorithms closely reproduce wave packet propagation.

Time-dependent dipole moments are accurately calculated.

Polynomial scaling suggests feasibility for larger systems.

Abstract

In this work, we investigate the capability of known quantum-computing algorithms for fault-tolerant quantum computing to simulate the laser-driven electron dynamics in small molecules such as lithium hydride. These computations are executed on a quantum-computer simulator. Results are compared with the time-dependent full configuration interaction method (TD-FCI). The actual wave packet propagation is closely reproduced using the Jordan-Wigner transformation and the Trotter product formula. In addition, the time-dependent dipole moment, as an example of a time-dependent expectation value, is calculated using the Hadamard test. In order to include non-Hermitian operators in the dynamics, a similar approach to the quantum imaginary time evolution (QITE) algorithm is employed to translate the propagator into quantum gates. Thus, ionization of a hydrogen molecule under the influence of a complex absorbing potential can be simulated accurately. All quantum computer algorithms used scale polynomially rather than exponentially as TD-FCI and therefore hold promise for substantial progress in the understanding of electron dynamics of increasingly large molecular systems in the future.