Room T Quantum Topological State
STM Evidence of Room T Quantum Spin Hall State
Realizing robust quantum phases at room temperature has long been a holy grail in physics. Here we used advanced scanning tunneling microscopy with variable temperature and magnetic field control to uncover a room-temperature quantum spin Hall (QSH) edge state in the material Bi₄Br₄, a higher-order topological insulator.
This study provides microscopic, spectroscopic evidence of a gapless, topologically protected edge state at an atomically sharp step edge—an unmistakable signature of QSH physics. The insulating bulk exhibits a large energy gap exceeding 200 meV, and the edge state's response to magnetic fields confirms its protection by time-reversal symmetry.
The findings not only visualize the fundamental building blocks of higher-order topological phases but also open the door to room-temperature applications in quantum information and energy-efficient electronics. This marks a major step toward realizing practical quantum devices powered by topological physics.
Q MIND Lab explores how quantum materials like Bi₄Br₄ are reshaping our understanding of the quantum world—at temperatures we encounter every day.
Quantum Transport of Topological Hinge Modes in Bi4Br4 Nano Device
Topological materials are best known for their conducting surface states surrounding an insulating bulk—but some host even more exotic features. We have discovered quantum transport along one-dimensional hinge states in the topological insulator Bi₄Br₄, revealing an entirely new quantum phase in action. Using magnetoresistance measurements, the team observed Aharonov–Bohm oscillations, a hallmark of quantum phase coherence, as electrons travel along these hinge modes. These oscillations, periodic in h/e, confirm that the hinge states support coherent quantum transport.
This study marks the first demonstration of quantum interference in topological hinge modes—proof that these one-dimensional edge states not only exist, but also carry quantum phase information. This bring us closer to designing low-power, topologically protected quantum devices that harness the unique properties of hinge-bound electron flow. Q MIND Lab will explore how these "quantum highways" could reshape the future of electronics.
Looking Ahead
Q MIND is developing monolayer Bi₄Br₄ devices to realize the quantum spin Hall effect at room temperature. Achieving topological transport, i.e., dissipationless electron flow, at room temperature will lay the foundation for ultra energy-efficient electronics built on topologically protected edge states.