Since its inception about two centuries ago thermodynamics has sparkled continuous interest and fundamental questions. According to the second law no heat engine working between two heat reservoirs at temperatures T1>T2 can have an efficiency larger than Carnot's efficiency η^c=1−T2/T1. The latter can be achieved by the Carnot engine, which however ideally operates in infinite time, hence delivers null power. A question that is currently in the limelight of current investigation is whether the Carnot efficiency can be achieved at finite power. I focus on quantum Otto engines and show that when the working substance is at the verge of a second order phase transition diverging energy fluctuations can enable the asymptotic approach towards the Carnot point at finite power. The rate of such approach is dictated by the critical indices, thus showing the universal character of our analysis.

Prof. Rosario Fazio obtained his PhD degree from the University of Catania in 1989, where he became Assistant Professor in 1990 and Associate Professor in 1998. He moved in 2001 to the Scuola Normale Superiore in Pisa, and in 2005 became full Professor in SISSA, Trieste. He returned to the Scuola Normale Superiore in 2008, of which he is still Professor of Condensed Matter Physics. In 2016 he became the Head of the Condensed Matter and Statistical Physics Sector of ICTP. Currently, he is also a Visiting Professor at the Center for Quantum Technologies, National University of Singapore. His main research interests are on quantum transport in nanostructures, superconductivity (Josephson junction arrays, superconducting nanocircuits), quantum simulators (cold atoms in optical lattices, QED-arrays), non-equilibrium dynamics of many-body systems, and quantum information processing.