IQM and Volkswagen Advance Quantum-Classical AFQMC to Simulate Next-Generation Battery Chemistry

European quantum hardware manufacturer IQM Quantum Computers (Nasdaq: IQMX) and Volkswagen Group Innovation have demonstrated algorithmic and experimental advances in Quantum-Classical Auxiliary-Field Quantum Monte Carlo (QC-AFQMC), reducing the classical post-processing runtime scaling of the hybrid electronic structure algorithm by an order of magnitude. Detailed in a technical study titled Quantum-Classical Auxiliary-Field Quantum Monte Carlo at the Edge of Practicability, the collaboration achieved up to a 124× reduction in classical execution time for a 50-orbital benchmark and validated the workflow on IQM’s commercial Emerald superconducting processor.

Simulating complex chemical reactions—such as the intermediate stages of lithium-air battery cycles—presents severe challenges for classical electronic structure methods due to the exponential growth of Slater determinants needed to capture strong electron correlation. Standard classical phaseless AFQMC (ph-AFQMC) mitigates sign problems by projecting random walks against a trial wavefunction; however, the method incurs systematic bias if that trial state cannot accurately represent multi-reference character. While QC-AFQMC leverages a quantum computer to prepare high-fidelity multi-determinant trial states, calculating the overlaps between the quantum trial state and classical Monte Carlo walkers has historically created a prohibitive computational bottleneck.