Quantum superconducting diode effect with perfect efficiency above liquid-nitrogen temperature

Abstract: The superconducting diode is an emergent device that juggles between the Cooper-paired state and the resistive state with unpaired quasiparticles. Here, we report a quantum version of the superconducting diode, which operates solely between Cooper-paired states. This type of quantum superconducting diode takes advantage of quantized Shapiro steps for digitized outputs. The devices consist of twisted high-temperature cuprate superconductors, and exhibit the following distinguished characteristics: (1) a non-reciprocal diode behavior can be simply initiated by current training without applying an external magnetic field; (2) perfect diode efficiency is achieved under microwave irradiations at a record-high working temperature; (3) the quantized nature of the output offers high resilience against input noises. These features open up unprecedented opportunities toward developing practical dissipationless quantum circuits.