First Measurement of Stretched Exponential Decoherence Parameter β on Analog Quantum Hardware Reveals Platform-Dependent Dynamics

Quantum decoherence is universally assumed to follow Markovian (simple exponential) dynamics in analog quantum processors, yet this assumption has never been experimentally tested. We report the first measurement of the stretched exponential parameter β characterizing coherence decay on an analog quantum platform. Using QuEra's Aquila Rydberg atom processor, we measure β = 3.52 ± 1.05 across three system sizes (N=4, 6, 8 atoms), significantly exceeding values observed on gate-based superconducting platforms (β = 1.27 ± 0.25, IBM Quantum). This 2.8-fold difference demonstrates fundamental platform-dependent variations in decoherence mechanisms. The observed super-exponential decay (β > 2.5) indicates strong non-Markovian effects in neutral atom systems, contradicting the standard Markovian assumption. We observe a trend toward larger β values with increasing system size, suggesting many-body correlation effects. These results establish β as a platform-dependent observable and open new directions for characterizing decoherence in quantum processors.