From Traveling Waves to Synthetic Gauge Fields: A Field-Free Route to Superconducting Diode Effect

Abstract

The superconducting diode effect requires the forward and reverse bias currents to differ, a scenario achieved via inversion and time-reversal symmetries broken together. The latter, and the more crucial one, is inevitably achieved by a magnetic field. Here, we show that a spatio-temporally driven chemical potential of the form, $μ_j(t)=μ+V\cos(ωt+\kd j)$, achieves both at once. Applied to a helical Shiba chain, the drive transmutes a traveling Peierls phase via generating an odd-in-momentum term, equivalent to an imaginary next-nearest-neighbour Haldane-like hopping in real space. Remarkably, the protocol is spin-blind, which renders the time-reversal breaking via a synthetic gauge flux rather than an effective Zeeman field. The rectification is odd in the drive wavevector, with exact zeros at $\kd=nπ$ and an analytical optimum at $\kd=2π/3$. It is however, even in the exchange coupling, $J$ and persists even at $J=0$. Furthermore, the rectification scales inversely with the pair-breaking gap, yielding approximately $50\%$ rectification in the topological phase and $10\%$ in the trivial phase. Symmetry breaking is thus drive-controlled, allowing it to be switched on, tuned, and reversed without an external magnetic field.