Harvard’s high-temperature superconductor diode breakthrough

Physicists have been captivated by superconductors for decades, yet these materials, facilitating the flawless flow of electrons, typically unveil their quantum marvel only at temperatures near absolute zero, making practical applications challenging. Harvard’s Professor Philip Kim and his team have presented a groundbreaking approach, outlined in the journal Science, to create and manipulate a prominent class of higher-temperature superconductors known as cuprates. Their low-temperature device fabrication method led to a potential candidate for the world’s first high-temperature superconducting diode, crucial for industries like quantum computing.

Kim emphasizes the feasibility of high-temperature superconducting diodes without magnetic fields, heralding new avenues for exploring exotic materials. Cuprates, particularly bismuth strontium calcium copper oxide (BSCCO), defied expectations by exhibiting superconductivity at relatively “high” temperatures, such as -288 Fahrenheit (-177 Celsius). Overcoming the complexity of handling these materials, the team, led by S. Y. Frank Zhao, achieved a clean interface between ultra-thin BSCCO layers using a cryogenic crystal manipulation method.

Splitting BSCCO into layers one-thousandth the width of a human hair, Zhao stacked them with a 45-degree twist, preserving superconductivity at the delicate interface. The team observed different maximum supercurrents depending on the current’s direction, showcasing electronic control over the interfacial quantum state by reversing polarity.

This breakthrough allows for a switchable, high-temperature superconducting diode—an advancement with profound implications for quantum computing. Zhao emphasizes its significance as a starting point for exploring topological phases with quantum states resilient to imperfections.

Collaborating with researchers from the University of British Columbia and Rutgers University, the team benefited from theoretical predictions by Marcel Franz and Jed Pixley. The successful reconciliation of experimental observations and new theoretical developments by Pavel A. Volkov at the University of Connecticut marks a crucial step in advancing our understanding of high-temperature superconductors.

Source: Harvard University

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