Condensed-matter occupies a large place in physics, and the theoretical concepts developed for these problems have often had an impact in other fields of physics. Likewise, the research carried out at the IPhT on condensed-matter systems has been tightly connected to other fields of theoretical physics, such as statistical physics, field theory, or integrable systems. In the last few years we focused on the following directions: topological states of matter, many-body problems, systems far from equilibrium, and disordered systems.
Quantum phases of matter with topological properties – subject of the 2016 Nobel Prize - represent a very active topic worldwide. Among these, systems supporting Majorana modes are actively studied, in part because they could be used in future device for quantum information processing.
Quantum many-body systems where the interactions between the particles play a central role, where non-perturbative (or beyond mean-field) effects need to be taken into account, are challenging problems. A prominent example is that of high-temperature (HT) cuprate superconductors. They have been studied theoretically and experimentally for several decades, but some key questions remain unsolved.
The field of quantum systems which are far from equilibrium has developed rapidly in the last decade, in part thanks to the advances on the experimental side (cold atoms, artificial light-matter systems, etc.). One way to set a system out-of-equilibrium is to perform a quantum quench. There, an isolated system is prepared in some simple state at time $t=0$ (not an eigenstate of the Hamiltonian) and then it evolves unitarily for $t>0$. Such protocols allow to address important questions about the equilibration or transport in isolated quantum systems, and to discuss the role played by interactions. We have also introduced a Quantum Monte Carlo (QMC) method for interacting systems far from equilibrium, the first diagrammatic QMC using an explicit sum of the Feynman diagrams in terms of an exponential number of determinants.
A new phase of matter has triggered a huge activity I the last few years. Dubbed many-body localization, it is the interacting counter part of the (single-particle) Anderson localization. Such disordered systems display many interesting anomalous properties, like the absence of thermalization.
|Juan Manuel Aguiar|
Our weekly seminar takes place every Monday at 14:00.
Postdoctoral positions are available each year in the Fall. Check this page or contact any staff member of the group.
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The full postal adress of IPhT is: Institut de Physique Théorique, CEA/Saclay, Bat 774 Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France.
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