We report evidence consistent with non-exponential decoherence in superconducting transmon qubits. Ramsey interferometry data from five qubits on IBM Quantum hardware show that a stretched-exponential model f(t) = exp(-(t/T2 ) beta) fits the observed decay better than the standard exponential (beta = 1). On our primary qubit (Q0), we measure beta = 2.06 with R2 = 0.9964 versus R2 = 0.9586 for the exponential, with Bayesian Information Criterion favoring the stretched model by 46 units. While non-exponential decay in superconducting qubits has been previously observed in the context of 1/f noise 4, the present work provides a systematic multi-qubit characterization with a fully reproducible protocol and proposes a falsifiable geometry-dependent prediction (RAB != 1) that distinguishes this framework from collapse-model alternatives.
Marcos Manse (Tue,) studied this question.