Phase-resolved multichannel quantum escape between limit cycles
Driven-dissipative quantum systems can recover stable dynamical attractors in the semiclassical limit, including coexisting limit cycles. At finite fluctuation strength, this classical coexistence becomes quantum metastability: the corresponding oscillatory states undergo rare fluctuation-induced transitions. We demonstrate phase-resolved quantum escape between two such states in a driven optomechanical resonator. Unlike escape from fixed points, switching between extended attractors occurs across a periodic basin boundary and depends on the phase at which fluctuations approach it. Using quantum-jump trajectories across a controlled quantum-to-classical crossover, we reconstruct the escape geometry directly from switching events. Escape from the small-amplitude cycle proceeds through a single radial corridor and exhibits near-Arrhenius scaling, whereas escape from the large-amplitude cycle involves competing phase-localized corridors with distinct effective activation scales. The resulting curvature in the switching-rate scaling, together with event-conditioned phase distributions, identifies finite-fluctuation multichannel quantum escape between extended attractors.