Natural Sciences and Applied Technology
A Comparative Study of QAOA and Classical Metaheuristics for Inventory Optimization
Poonam Chaudhary, Pranav Singh, Sneha Kandacharam, Rajan Gupta
Abstract
We investigate whether the Quantum Approximate Optimization Algorithm (QAOA) can compete with classical metaheuristics for multi-product, multi-location retail inventory optimization under demand uncertainty. We formulate the binary inventory decision problem as a Quadratic Unconstrained Binary Optimization (QUBO) model and benchmark QAOA (simulated via classical statevector simulation, $p=2$ layers) against Mixed-Integer Linear Programming (MILP), Simulated Annealing (SA), Genetic Algorithms (GA), and Tabu Search across problem sizes from $n=5$ to $n=200$ binary variables, using Walmart sales and Kaggle retail demand datasets. Our key finding is a \textbf{negative result}: while QAOA achieves a 2.3\% optimality gap and 97\% constraint satisfaction at small scales ($n \leq 20$), it is not competitive with classical metaheuristics at practical problem sizes. Classical heuristics---particularly SA and Tabu Search---consistently outperform QAOA on all instances tested and scale efficiently to $n=200$, whereas QAOA simulation becomes intractable beyond $n=30$ due to exponential memory requirements. We do not claim any quantum speedup. This comparative study provides important insights into the limitations of current QAOA implementations for supply chain problems, including the effects of penalty parameter scaling, barren plateaus in the optimization landscape, and circuit depth constraints. We additionally present an economic sensitivity analysis linking macroeconomic indicators to optimal inventory decisions and a rolling-horizon proof-of-concept for multi-period planning.