Vitaly Efimov and Rudolf Grimm win inaugural Faddeev Medal

The Faddeev medal was inaugurated in 2016 by the Topical Group on Few-Body Systems & Multiparticle Dynamics (GFB) of the American Physical Society and the European Research Committee on Few-Body Problems in Physics (ERCFBP) to recognize distinguished achievement in Few-Body Physics. It is named in honor of our distinguished colleague Ludwig Faddeev. The medal is awarded every three years to a scientist (or scientists) who advanced the field of few-body physics significantly — either through ground-breaking research or due to crucial progress achieved over the course of a career.

An international panel of experts, chaired by G. Orlandini (Trento), has selected the winners of the 2018 award. They are:

Vitaly Efimov:For the theoretical discovery of a series of weakly-bound three-body quantum states known as Efimov states.

Rudolf Grimm: “In recognition of his ground-breaking experiments confirming the Efimov effect.

The prize consists of US$1250 for each of the winners, a medal, and an invitation to the 22nd International Conference on Few-body Problems in Physics in Caen, France, next July, to participate in a special session there, devoted to the presentation of the medals. (For more details on FB22, please see

In the early 1970s Vitaly Efimov was studying the binding of the three-nucleon system and realized that the two-nucleon system has a near-threshold bound state. Efimov showed that, if a two-body interaction generates a bound state at threshold then the corresponding three- body system has an infinite number of three-body bound states, all of which are copies of one another, related via magnification by a specific factor which he calculated. Efimov also computed the impact that finite two-body binding energy would have on his prediction. This remarkable result was followed by an intensive search for systems that manifested this behavior, but no nuclear systems could be firmly established as candidates for the “Efimov effect”.

This is one of the most counterintuitive quantum phenomena present in a system of just a few particles, but it is also a very general result. The universality of the phenomenon predicted by Efimov led to a search for its signatures in various branches of physics, and the hope that it could provide a more profound insight into strongly-correlated systems.

For approximately three decades, the Efimov effect remained largely a purely theoretical curiosity; nature seemed to not co-operate by producing the conditions necessary for its occurrence. This changed in 2006 when a team led by Rudolf Grimm, from the University of Innsbruck, Austria, used the unique properties of ultracold quantum gases to control interatomic interactions in a gas of Cesium atoms. They produced the first Efimov resonance in a sample of Cesium atoms at temperatures of 10’s of nano-Kelvin. This observation brought to life the Efimov effect, and initiated a new, highly active, research field dedicated to probing its intimate properties. Today, the Efimov effect has been verified by several other groups triggering an evergrowing number of opportunities to explore new physics associated with it in different fields, including atomic, nuclear, hadronic, chemical, and condensed matter physics.

GFB and the ERCFBP are delighted to have two such distinguished recipients of the inaugural Faddeev medal. We also want to express our gratitude to Springer and to FB22, for financial support that made this award possible.

The next Faddeev medal will be awarded at the 23rd International Few-body Conference in 2021. It is anticipated that nominations will open in Summer 2019.