China Advances Superconducting Diodes to High Temperatures

For the first time, researchers in China have demonstrated a high-temperature superconducting diode effect, allowing a supercurrent to flow in both directions. This breakthrough, published in Nature Physics, addresses the noisy signals that pose fundamental challenges in quantum computing.

Ding Zhang, a physicist at Tsinghua University and the Beijing Academy of Quantum Information Sciences, explained that most reported superconducting diodes operate at low temperatures around 10 Kelvin and often require an external magnetic field, but their work achieves diode efficiency at temperatures exceeding 77 Kelvin without needing a magnetic field.

The team utilized cuprate superconductors, known for their high critical temperatures, to create a Josephson junction, enabling control over superconducting voltages through a technique that induces asymmetry in the junction.

Their method allows toggling between zero and a discrete finite voltage by irradiating the junction with microwaves, depending on the direction of the applied supercurrent. This new 'quantum superconducting diode effect' ensures current is carried entirely by Cooper pairs in both directions, avoiding noise generated by electron scattering, which is prevalent in conventional current.

Zhang noted that this technique could apply to various superconductors and may lead to superconducting diode effects at even higher temperatures, potentially over 100 Kelvin. The implications for quantum computing are significant as this advancement might pave the way for more practical applications in the field.