Physicists Push Superconducting Diodes to Higher Temperatures

Physicists in China have invented a high-temperature superconducting diode for the first time, which industry insiders mentioned will decrease noise in potential quantum computers. The device makes it possible to conduct supercurrent in different ways according to its direction, even at temperatures above the level of liquid nitrogen. Unlike previous generations that only operated at extreme cold, this new technique brings the superconducting diode a step closer to real-world use, one of several obstacles for quantum technologies to become more stable, scalable , and practical beyond laboratory setups.

High-Temperature Superconducting Diode Achieved Without Magnetic Fields

According to a Nature Physics report, the research team led by Ding Zhang of Tsinghua University used cuprate superconductors to create the diode effect without applying an external magnetic field. The study describes how pre-existing superconducting diode devices had operated only at, or near 10 Kelvin, and with poor efficiency, making them impractical for widespread use. The new result shows good diode action out to temperatures above 77 Kelvin, a great leap for superconducting electronics.
Superconductors transmit electricity without resistance at temperatures below a critical temperature through the formation of Cooper pairs, although most superconductors at very low temperatures, which makes them costly and cumbersome to use in practice.

Twisted Cuprate Josephson Junction Enables Noise-Free Superconducting Diode

To make this happen, the scientists stacked two thin flakes of cuprate and twisted them at specific angles relative to each other, creating something called a Josephson junction. Applying current pulses in a controlled way and adding microwave signals created an axial electrical asymmetry, for which the device changed between on-off states of the voltage with a strong diode effect at high stability that was entirely dominated by Cooper pairs.

This advance may benefit quantum computing by avoiding electron noise; the method works with many superconductors, potentially exceeding 100 Kelvin for practical quantum circuits.