# Digital Quantum Simulation of Wavepacket Correlations in a Chemical Reaction

## TL;DR

This paper demonstrates how digital quantum circuits can accurately simulate wavepacket correlations in a chemical reaction, showing promise for quantum chemistry applications.

## Contribution

A new hybrid quantum-classical method for computing wavepacket correlation functions using digital quantum simulation and a reduced-depth MFE protocol.

## Key findings

- Quantum-estimated correlation functions match classical simulations across the full time domain.
- The MFE protocol achieves accurate results with reduced circuit depth.
- The method is validated on the H + H2 exchange reaction with high accuracy.

## Abstract

We present hybrid quantum–classical algorithms to compute time-dependent Møller wavepacket correlation functions via digital quantum simulation. Reactant and product channel wavepackets are encoded as qubit states, evolved under a discretized molecular Hamiltonian, and their correlation is reconstructed using both a modified Hadamard test and a multi-fidelity estimation (MFE) protocol. The method is applied to the collinear H + H2 exchange reaction on a London–Eyring–Polanyi–Sato potential energy surface. Quantum-estimated correlation functions show quantitative agreement with high-resolution classical wavepacket simulations across the full time domain, reproducing both short-time scattering peaks and long-time oscillatory dynamics. The ancilla-free MFE protocol achieves matching results with reduced circuit depth. These results provide a proof of principle that digital quantum circuits can be used to accurately calculate the wavepacket correlation functions for a benchmark chemical reaction system.