**The quantum Hall effect (QHE), which was previously known for two-dimensional (2-D) systems, was predicted to be possible for three-dimensional (3-D) systems by Bertrand Halperin in 1987, but the theory was not proven until recently by researchers from the Singapore University of Technology and Design (SUTD) and their research collaborators from around the globe.**

**The Hall effect, a fundamental technique for material characterization, occurs when a magnetic field deflects the flow of electrons sideways and leads to a voltage drop across the transverse direction. In 1980, researchers made a surprising observation when measuring the Hall effect for a two-dimensional (2-D) electron gas trapped in a semiconductor structure—the measured Hall resistivity showed a series of completely flat plateau, quantized to values with a remarkable accuracy of one part in 10 billion. This became known as the QHE.**

**QHE has since revolutionized the fundamental understanding of condensed matter physics, generating a vast field of physics research. Many new emerging topics, such as topological materials, can also be traced back to it.**

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