EPJ Plus Highlight - Investigating charge transport in hybrid nanowires

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Published on 21 November 2025

Analysis reveals how electron-hole pairs are reflected and transmitted across the interfaces of a hybrid nanowire – featuring alternating sections of a normal conductor and a high-temperature superconductor.

High-temperature superconductors are quickly opening up new possibilities for nanoscale circuits, which are likely to become key building blocks of future quantum technologies. As this research advances, a deep understanding of how electrical currents flow through superconductors dominated by quantum effects is becoming increasingly important.

Through theoretical analysis detailed in EPJ Plus, Francisco Estrella and Linda Reichl at the University of Texas at Austin provide one of the most detailed descriptions to date of how electron-hole pairs behave within hybrid nanowires – made from alternating sections of normally conducting material and a high-temperature superconductor. Their results clarify how hybrid nanowires could become a reliable testbed for fundamental quantum phenomena and could help pave the way for their use in real-world quantum technologies.

High-temperature superconductors are a fast-developing class of materials that allow electrical currents to flow with zero resistance, without the ultra-cold temperatures required by more conventional superconductors. When formed into nanowires, electrons and their corresponding holes can travel through them more easily without being scattered by impurities, providing a more reliable platform for quantum phenomena to emerge.

In their study, Estrella and Reichl investigated this transport within a hybrid nanowire, where the high-temperature superconductor TBCCO is interfaced with a normally conducting material at regular intervals. Drawing from the latest theories of superconductivity, they determined the geometric and thermal conditions that enable TBCCO nanowires to maintain superconducting states within this structure. Using this framework, they then determined how electrons and holes are reflected and transmitted across the nanowire’s interfaces.

The duo’s results show that the process is strongly affected by ‘quasi-bound states’, which emerge when electrons and holes are temporarily trapped at the nanowire’s interfaces – impacting the overall flow of current. From here, they identified the energy ranges for these states at which reflection and transmission become equally likely, an insight that could help researchers better assess the capabilities and limitations of nanowires used in emerging quantum technologies.