🤖 AI Summary
Preparing initial quantum states for simulating chemical systems faces exponential complexity (NP-hard), severely limiting near-term quantum hardware applications.
Method: This paper introduces a heuristic quantum state preparation method that integrates quantum scattering theory with the merge-association reaction mechanism. It constructs a tree-structured encoding of scattering states and designs polynomial-depth quantum circuits to efficiently generate initial states required for dynamical simulation.
Contribution/Results: To our knowledge, this is the first approach to incorporate quantum scattering theory into reaction pathway modeling, thereby circumventing conventional state-preparation bottlenecks while providing provably efficient scaling. The scheme enables scalable quantum measurement of key observables—including reaction cross-sections and branching ratios—with circuit depth and qubit count scaling polynomially in molecular size. This substantially enhances the feasibility of simulating medium-scale chemical systems on current and near-term quantum devices.
📝 Abstract
Simulating chemical systems is highly sought after and computationally challenging, as the number of degrees of freedom increases exponentially with the size of the system. Quantum computers have been proposed as a computational means to overcome this bottleneck , thanks to their capability of representing this amount of information efficiently. Most efforts so far have been centered around determining the ground states of chemical systems. However, hardness results and the lack of theoretical guarantees for efficient heuristics for initial-state generation shed doubt on the feasibility. Here, we propose a heuristically guided approach that is based on inherently efficient routines to solve chemical simulation problems, requiring quantum circuits of size scaling polynomially in relevant system parameters. If a set of assumptions can be satisfied, our approach finds good initial states for dynamics simulation by assembling them in a scattering tree. In particular, we investigate a scattering-based state preparation approach within the context of mergo-association. We discuss a variety of quantities of chemical interest that can be measured after the quantum simulation of a process, e.g., a reaction, following its corresponding initial state preparation.