40 years of the quantum Hall effect

The discovery of the quantum Hall effect (QHE) marked a turning point in condensed-matter physics. The measurement of the Hall resistance showed that electronic resistance could be defined precisely in terms of fundamental constants, even in a disordered and irregular sample. Over the past 40 years, the QHE has inspired new theories and led to experimental discoveries in a range of fields going beyond solid-state electronics to photonics and quantum entanglement. In this Viewpoint, physicists reflect on how the QHE has influenced their research. Over the past 40 years, the quantum Hall effect (QHE) has inspired new theories and led to experimental discoveries in a range of fields going beyond solid-state electronics to photonics and quantum entanglement. In this Viewpoint, physicists reflect on how the QHE has influenced their research. Klaus von Klitzing received the Nobel Prize in Physics in 1985 for discovering the quantum Hall effect, 5 years after the unexpected observation at the Grenoble High Magnetic Field Laboratory. His research focuses on electrical and optical measurements on low-dimensional electron systems. In 2018, he retired as director at the Max Planck Institute for Solid State Research in Stuttgart. Tapash Chakraborty is a retired professor of physics from the University of Manitoba, Canada. He was also the Canada Research Chair in Nanoscale Physics (2003–2017). He has worked on various aspects of the quantum Hall effect since the early days of the discovery. He has also worked on the electronic properties of quantum dots and various other nanoscale systems. In addition to numerous articles, he has authored books and book chapters. He is a fellow of the American Physical Society. Philip Kim is professor of physics at Harvard University. His group and Andre Geim’s group at Manchester University are the first who observed the half-integer shift in the quantum Hall effect in graphene in 2005, experimentally demonstrating the linear Dirac dispersion. The Kim group has actively been pursuing novel quantum transport in graphene and other 2D materials. Vidya Madhavan obtained her bachelor’s and master’s degrees from the Indian Institute of Technology in India. After obtaining her Ph.D. from Boston University in 2000, she held a postdoctoral appointment at the University of California, Berkeley, from 1999 to 2002. She joined the physics faculty at Boston College in 2002 and is currently a full professor at the University of Illinois, Urbana-Champaign. Xi Dai received his Ph.D. in 1999 at the Institute of Theoretical Physics, Chinese Academy of Sciences. He worked there for more than 10 years before he joined Hong Kong University of Science and Technology in 2017 as a chair professor in the physics department. James McIver received his Ph.D. from Harvard University in 2014. He subsequently did a postdoc at the Max Planck Institute for the Structure and Dynamics of Matter, where he is currently a research group leader. His research focuses on the electrical transport properties of optically driven quantum materials, including transport from topological Floquet states in graphene. Yoshinori Tokura graduated with a Ph.D. from the University of Tokyo in 1981. He is currently Distinguished University Professor of the University of Tokyo as well as the founding director of the RIKEN Center for Emergent Matter Science. He has been working on correlated and topological electron physics, including high-temperature superconductors, Mott transitions, colossal magnetoresistance oxides, multiferroics, skyrmion science and magnetic topological insulators. Lucile Savary received her Ph.D. from University of California, Santa Barbara, in 2014. After a postdoctoral position at MIT, she joined Ecole Normale Superior at Lyon as a permanent researcher. Her research focuses on exotic phenomena in real systems, with an emphasis on frustrated magnetism, and includes quantum spin liquids, the anomalous Hall effect and non-centrosymmetric superconductors. Daria Smirnova received her Ph.D. in Physics in 2016 from the Australian National University, where she currently holds a prestigious Discovery Early Career Research Fellow position supported by the Australian Research Council. Her research interests include topological photonics, nonlinear nanophotonics and multipolar electrodynamics. Ana Maria Rey received her Ph.D. from the University of Maryland at College Park in 2004. She is currently a JILA fellow, a NIST fellow and an adjoint professor in the physics department at the University of Colorado, Boulder. Rey’s research is on how to control and manipulate ultracold atomic systems for use as quantum simulators, precision measurements and quantum computation. Claudia Felser studied at the University of Cologne, completing her doctorate in physical chemistry in 1994. She is currently a director at the Max Planck Institute for Chemical Physics of Solids in Dresden. She is a fellow of the American Physical Society and the Institute of Physics, London, a member of the Leopoldina, the German National Academy of Sciences, and an International Member of the National Academy of Engineering, USA. In 2019, she received the American Physical Society James C. McGroddy Prize for New Materials together with Andrei Bernevig and Xi Dai. Johannes Gooth studied physics at the University of Hamburg and Lund University, completing his doctorate in physics in 2014. After two postdocs at IBM Research – Zurich and Harvard University, he became an independent research group leader at the Max Planck Institute for Chemical Physics of Solids in Dresden in 2018. Xiaoliang Qi received his Ph.D. from Tsinghua University in 2007, then moved to the United States for postdoctoral work. Since 2010, he has been a faculty member at Stanford University. His research interest is the interplay of quantum entanglement, quantum gravity and quantum chaos and he has also worked on topological states and topological phenomena in condensed-matter systems.