How Error-Mitigated Quantum Computers Are Reaching Beyond State-of-the-Art Classical Simulation

We studied the dynamics of a Floquet quantum magnet on heavy-hex lattices containing up to 74 spins using an IBM Heron R3 processor. QESEM, Qedma’s Error Suppression and Error Mitigation software, enabled high-precision quantum simulations at intermediate physical times, a regime in which the leading classical methods we investigated, including tensor-network and Sparse Pauli Path simulations, could not capture the dynamics because of prohibitive memory and runtime requirements, despite extensive computational resources, including NVIDIA H100 GPUs and over 500,000 CPU-hours across ~13,000 nodes of the Fugaku supercomputer. Our results address a physically important question beyond the reliable reach of today’s leading classical methods, providing evidence that long-lived prethermal oscillations of the studied Floquet magnet persist in large-scale systems, contrary to the intuitive expectation that they would gradually disappear as a finite-size effect. The reliability of these findings is supported by multiple independent validation tests, including cross-platform validation on Quantinuum trapped-ion hardware (H2 and Helios) and unbiased error mitigation backed by rigorous theoretical accuracy guarantees, among others. These results illustrate how advanced quantum error mitigation is enabling today’s quantum processors to become quantitative scientific tools for probing many-body physics beyond the reach of classical simulation methods. One of the central promises…