One driving-field rule optimizes both supercurrent and quantum noise

By applying a 'ratchet universality' law to biharmonically-driven tunnel junctions, the authors show that one specific waveform shape simultaneously maximizes supercurrent rectification in superconducting diodes and minimizes excess quantum (shot) noise. The optimal drive pushes noise so low it enables production of nonclassical photon states. The finding retroactively explains earlier puzzling experimental results and points toward a single design principle for superconducting electronics and quantum computing hardware.