Hamiltonian Reordering for Shallower Trotterization Circuits

Quantum simulation is a popular application of quantum computing, but its practical realization is hindered by the technical limitations of current devices. In this work, we focus on preprocessing Hamiltonians before Trotterization to generate shallower evolution circuits, which are less prone to noise and decoherence. Specifically, we apply graph coloring techniques to reorder Pauli terms and increase "gate parallelism". We benchmark two coloring algorithms, and report the depth reduction and computational overhead. Then, we examine how these optimized circuits affect the performance of the Quantum Approximate Optimization Algorithm (QAOA). Our results show that shallower circuits lead to faster convergence and reach higher energy levels compared to their non-reordered counterparts.