Ratchet Universality and optimal suppression of shot noise in biharmonically-driven tunnel junctions

This work discusses two retrodictions of the ratchet universality (RU) law which explain previous numerical and experimental findings concerning the diode effect in conventional superconducting tunnel-junctions (TJ) and the controlled suppression of electron-hole pair generation in a TJ, both under biharmonic driving fields. We demonstrate that the interplay between the RU law and the Heisenberg's uncertainty principle leads to a universal scenario of optimal quantum transport. Specifically, we demonstrate that the RU driving field maximizes the diode's efficiency while yielding a maximal rectification range for the supercurrent, on the one hand, and optimally reduces the excess quantum noise with respect to the dc noise level, thus allowing for the efficient production of nonclassical photonic states. These results suggest that the RU law seems essential for any optimal application of the ratchet effect, particularly in the contexts of superconducting integrated power electronics, electron quantum optics, and quantum computing.