A Hot Topic in the Quantum Hall Effect

Jason Alicea
2018 Physics  
A round 40 years ago, physicists stumbled on an elegant recipe for creating exotic phases of matter: Pour electrons into a clean two-dimensional environment, add a magnetic field, and allow to cool. Out comes a dazzling variety of so-called fractional quantum Hall phases. Certain types of fractional quantum Hall phases, called non-Abelian, provide a potential platform for intrinsically error-resistant quantum computation. However, unambiguously identifying these phases poses a notorious
more » ... e for experimentalists, as measurements often do not uniquely pinpoint which of several candidate phases is present. Experiments published last month [1] provide direct evidence that a previously studied quantum Hall phase first observed long ago [2] is indeed non-Abelian. In a delightful surprise, the observations appear to rule out the two leading candidate phases that were expected from theory! Now David Mross and colleagues from the Weizmann Institute of Science in Israel [3] and Chong Wang and colleagues from Harvard University [4] describe a possible resolution: Because of disorder, the system might harbor patches of each of the two theoretically expected candidates, which combine to form a distinct non-Abelian phase compatible with observations. Further work is required to ascertain whether experiments conform to this scenario, but the idea of new phases emerging from hybrids of competing states could prove useful in the broader search for non-Abelian systems. physics.aps.org
doi:10.1103/physics.11.70 fatcat:vvh2kpx4h5getj47kymmbsbuha