Oliver E. Buckley Condensed Matter Physics Prize (2021)

Researchers’ Paradise: The quantum Hall Effect
From the very beginning of my career, I appreciated the importance of high-quality materials. Studying the art of MBE growth, and later inheriting it to colleagues, enabled me the flexibility to dream. I recall the excitement in obtaining my first one-million-mobility 2DEG in GaAs, leading to distinct, marvelous, fractional states in the Quantum Hall Effect (QHE). The amazing features of the QHE, which became more abundant and distinct over time, were captivating. In the past 40 years, the QHE offered an unbelievable plethora of effects, many unexpected, providing a ‘play-ground’ for theorists and experimentalists alike. With the 2D bulk insulating, the edge is full of life. Mirroring the nature of the bulk, gapless 1D-like currents and heatwaves coexist, carrying fractional charged and chargeless quasiparticles, which obey abelian and non-abelian statistics. Applying my engineering background, I toyed with mesoscopic structures that forced the edge modes to obey external manipulations. Constructing artificial potential barriers led to charge partitioning and shot noise, revealing the quasiparticles charge and even its absence. Interfering the modes taught us of their wave-nature and their phase evolution in mesoscopic structures. Particles’ statistics became apparent when a two-particle interferometer was demonstrated. And recently, novel measurements of the thermal conductance provided a smoking gun for non-abelian fractional states. There is still plenty to discover.