A Tiny Twist Sparks a Quantum Revolution in Superconductors

By RIKEN March 20, 2025

Collected at: https://scitechdaily.com/a-tiny-twist-sparks-a-quantum-revolution-in-superconductors/

Scientists have discovered a revolutionary way to control superconductivity by twisting ultra-thin layers of a superconducting material.

This method allows precise tuning of the superconducting gap, a crucial factor for making quantum devices more efficient. Unlike previous approaches that focused on physical positioning, this breakthrough achieves control in momentum space, opening new doors for material science. Their findings could lead to advancements in energy-efficient technology, quantum computing, and the design of superconductors with customized properties.

Twisting Layers to Control Superconductivity

Scientists at the RIKEN Center for Emergent Matter Science (CEMS) and their collaborators have discovered a new way to control superconductivity by twisting ultra-thin layers of material. This breakthrough could lead to more energy-efficient technologies and advancements in quantum computing. By adjusting the angle between these layers, researchers were able to precisely modify the “superconducting gap,” a key factor in how these materials behave. Their findings were published today (March 20) in Nature Physics.

The superconducting gap represents the energy needed to break apart Cooper pairs. These are pairs of electrons that enable superconductivity at low temperatures. A larger gap allows superconductivity to function at higher temperatures, making it more practical for real-world applications. Tuning this gap is also essential for optimizing Cooper pair interactions at the nanoscale, which enhances the performance of quantum devices.

Moving Beyond Traditional Methods

Until now, most efforts to control the superconducting gap have focused on “real space,” adjusting the physical arrangement of particles. However, controlling it in “momentum space,” which maps the energy states of the system, has remained a challenge. Achieving this level of precision is crucial for developing the next generation of superconductors and quantum technologies.

In an effort to achieve this, the group began working with ultrathin layers of niobium diselenide, a well-known superconductor, deposited on a graphene substrate. Using advanced imaging and fabrication techniques, such as spectroscopic-imaging scanning tunneling microscopy and molecular beam epitaxy, they precisely adjusted the twist angle of the layers. This modification produced measurable changes in the superconducting gap within momentum space, unlocking a novel “knob” for precisely tuning superconducting properties.

Surprising Patterns and New Possibilities

According to Masahiro Naritsuka of CEMS, the first author of the paper, “Our findings demonstrate that twisting provides a precise control mechanism for superconductivity by selectively suppressing the superconducting gap in targeted momentum regions. One surprising discovery was the emergence of flower-like modulation patterns within the superconducting gap that do not align with the crystallographic axes of either material. This underscores the unique role of twisting in shaping superconducting properties.”

Future Applications and Next Steps

Tetsuo Hanaguri of CEMS, the last author, added, “In the short term, our research deepens the understanding of superconducting systems and inter-layer interactions, advancing the design of superconductors with tailored properties. In the long term, it lays the foundation for developing energy-efficient technologies, quantum computing, and beyond. Next steps involve investigating whether magnetic layers can be integrated into the structure to enable both spin and momentum selectivity. These advances could unlock new research opportunities and pave the way for developing innovative materials and devices.”

Reference: “Superconductivity controlled by twist angle in monolayer NbSe2 on graphene” 20 March 2025, Nature Physics.
DOI: 10.1038/s41567-025-02828-6