All-electrically controlled topological Josephson diode in quantum anomalous Hall insulator−superconductor hybrids

We propose and investigate an all-electrically controlled Josephson diode effect in a hybrid junction consisting of a quantum anomalous Hall insulator (QAHI) sandwiched between two topological superconductors (TSCs). Due to the spatial separation of two paired electrons from the chiral edge states, a transverse electric field applied across the two TSC leads imposes different energies on two paired electrons and modifies the spectrum of chiral Andreev bound states, consequently generating a sizable nonreciprocal supercurrent without the need for external magnetic fields. We further demonstrate two additional electrical control mechanisms: (i) tuning the chemical potential enhances the diode response by separating the superconducting gap from finite-size-induced gaps; and (ii) applying asymmetric electric fields to the two TSC leads enables precise and continuous modulation of the diode efficiency while preserving its polarity. The induced diode effect is shown to be robust against moderate disorders. Our results establish electrostatic gating as a powerful and practical approach to engineer and control nonreciprocal superconducting transport, providing a general framework for realizing electrically tunable topological Josephson diodes.