# Yoseph Imry

Wolf Prize Laureate in Physics 2016

**Yoseph Imry**

#### Affiliation at the time of the award:

**The Weizmann Institute of Science, Israel**

#### Award Citation:

**“For pioneering studies of the physics of mesoscopic and random systems”.**

#### Prize Share:

**None**

Prof. Yoseph Imry is the primary founding father of mesoscopic physics, the study of systems that are much smaller than everyday (macroscopic) objects but significantly larger than atoms. Imry originated and led the development of the principal concepts of this discipline, which is the foundation of nanoscience and nanotechnology.

Nanotechnology is not just a technical achievement – it brings in important quantum effects. On the macroscopic scale quantum effects are seen only in superconductors and superfluids. Imry predicted that at mesoscopic scales quantum effects would be observed also in ordinary materials. For instance, at macroscopic scales the electric resistance of a normal conductor takes on continuously varying values; at small scales it can be only a well-defined multiple of e2/h, where e is the electron charge and h is Planck’s constant. In addition, a spontaneous electric current – a current without the need for an energy source like a battery – may exist in small rings made of normal conductors. This current is not simply characterized by its amplitude, but also by a phase, reflecting its quantum nature. On macroscopic scales such a current exists only in superconductors. The phase leads to conductance oscillations as a function of the magnetic flux flowing through the circuit and measured in units of h/e (the Aharonov-Bohm effect). Furthermore, both the amplitude and phase of the current are subject to quantum fluctuations. Imry’s predictions of persistent currents and of the resulting quantum effects in mesoscopic systems were originally met with skepticism, but were confirmed by subsequent experiments. The observed currents turned out to be unexpectedly large, a puzzle that baffled scientists for 20 years, until Imry resolved it by taking superconducting fluctuations into account.

Prof. Imry has also provided pioneering insights into the physics of phase transitions. His work on phase transitions in finite systems and low dimensions is crucial for mesoscopic physics. His theory of phase transitions in random fields with K.S. Ma is a seminal contribution, which has influenced the whole statistical physics community. Similarly, his analysis of the metal-insulator transition, including the derivation of experimentally testable scaling laws, has had a profound influence on the condensed matter community. His discussion of Bose condensation in solid He4 came three decades before the explosion of research on supersolids.

Prof. Imry is a physicist with impressive foresight, often well ahead of his time, who has spearheaded several fields of physics. For all these reasons he has been awarded the 2016 Wolf prize in Physics.