Table of contents
Open questions in the quantum many-body problem
Guest editor: Yvan Castin; Carlos Sá de Melo
Yvan Castin is Senior Researcher at the CNRS. A theoretician, he has been working at the Laboratoire Kastler Brossel, École normale supérieure, Paris, since his doctoral thesis on laser cooling of atoms, carried out under the supervision of Jean Dalibard and Claude Cohen-Tannoudji from 1988 to 1992. Together with Klaus Mølmer and Jean Dalibard, he contributed to the development of the Monte Carlo wave function method. Since 1995, he has been working on gaseous atomic Bose-Einstein condensates in the "cold atom" group set up by Claude Cohen-Tannoudji, before adding strongly interacting fermion superfluids as a second string to his bow in 2004, following Christophe Salomon in the "ultracold Fermi gases" group, of which he is responsible for the theoretical part. He is responsible for several original results on the four-body Efimov effect and cluster expansion for the unitary fermion gas, spin squeezing limits and coherence time of a condensate in an isolated Bose gas, and collisionless sound damping in superfluids, in collaboration with Alice Sinatra, Ludovic Pricoupenko, Felix Werner, Shimpei Endo, and others. He received (with Laurent Lafforgue) the Jacques Herbrand prize from the Académie des Sciences in 2001, and in 2012 the Louis D. Foundation team prize, awarded to group leader Christophe Salomon.
Prof. Carlos A. R. Sá de Melo earned a PhD in theoretical physics at Stanford University (1991), specializing in quantum many-body physics, under the supervision of Prof. Sebastian Doniach (Bardeen Prize 2018), and was a postdoctoral fellow at the Science and Technology Center for Superconductivity in Illinois, mentored by Dr. Alexei Abrikosov (Nobel Prize 2003, deceased). After that he moved to the Georgia Institute of the Technology, where he is a professor of physics today. Prof. Sá de Melo is best known for his theoretical contributions to the evolution from Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) superfluidity in single- and two-band systems during the 1990’s and 2000’s, a phenomenon explored experimentally since the mid-2000’s. For his work on ultracold Fermi atoms and superfluids, he was awarded a two-year Visiting Fellow position at the Joint Quantum Institute (UMD-NIST) from 2006-2008, was elected Fellow of the American Physical Society in 2012, was granted a Simons Fellowship in 2017 for an extended visit to the Galileo Galilei Institute of Theoretical Physics (Florence, Italy), was presented the Fibonacci Prize in 2018 at the Quantum Complex Matter conference (Frascati, Italy), was elected Fellow of the American Association for the Advancement of Science in 2021, and was honored with a Mercator Fellowship by the German Research Foundation in 2024. His research on the crossover and quantum phase transitions from the BCS to the BEC regime in superfluids has influenced experimental and theoretical work not only in atomic, but also in nuclear and condensed matter physics.
