Title: Quantum advantage in noisy simulations of random circuit OTOCs Speaker:  Brayden Ware (Google Quantum AI) Date & Time:  December 3, 2025, 3:30pm Where to Attend:  ATL 3100A and Virtual Via Zoom: https://umd.zoom.us/j/2821742741?pwd=SWJSRm1DTGFoYUtVMllVSEo5bzdmdz09
Noisy quantum devices have been shown to vastly outperform known classical algorithms in the task of sampling outputs from random circuits, a task chosen not for its usefulness but specifically for maximizing quantum advantage. In this talk, we will discuss our effort to benchmark quantum advantage in measuring an observable rather than in a sampling task. For this task we use random circuit dynamics, which both  generate entanglement and magic rapidly with native device operations and which are amenable to theoretical analysis of ensemble averaged properties via a mapping to a ‘statistical model’. Using this analysis, we argue that ‘higher order out of time order correlations’ (OTOCs) – measured on the device using circuits with multiple time reversals– provide the strongest claim to quantum advantage. In particular, we explain a heuristic classical strategy that discards interference contributions which outperforms other classical method in large random circuits and thus provides the strongest challenge to the quantum advantage claim for the lowest order OTOC, and we explain how the experiment was used to validate the importance of interference for the final chosen circuits.
Reference: Google Quantum AI and Collaborators. Observation of constructive interference at the edge of quantum ergodicity. Nature 646, 825–830 (2025). https://doi.org/10.1038/s41586-025-09526-6
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