Magnetic-field tuning of quantum phase slips in a macroscopic granular aluminum film

Quantum phase slips (QPSs) fundamentally govern low-temperature dissipation in one-dimensional nanoscale superconductors but remain largely unexplored in macroscopic architectures lacking strict geometric confinement. In this work, the magnetic-field-tuned evolution of the macroscopic quantum tunneling regime is demonstrated in a wide granular aluminum film (7 × 0.8 mm2). Systematic zero-field current–voltage and magnetotransport measurements reveal that a perpendicular magnetic field systematically amplifies quantum fluctuations by suppressing the local phase-slip activation barrier, ΔF. The extracted QPS parameters exhibit a strongly anti-correlated scaling: ΔF decays monotonically, while the quantum attempt frequency Γqps increases exponentially, driving a continuous crossover into a phase-fluctuation-dominated regime. Furthermore, scaling of the residual low-temperature resistance reveals a pronounced renormalization relative to the single-channel limit. This behavior is accounted for by a percolative network comprising ∼105 parallel, quasi-one-dimensional superconducting channels. These findings establish the magnetic field as a robust tuning parameter for QPS dynamics in scalable thin-film architectures, offering critical operational insights for the design of resilient, phase-slip-based superconducting quantum hardware.