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Project

Elementary excitations in Fermi systems: From cold atoms to condensed matter.

When cooling down a system made of many interacting particles, one encounters new states of matter that display unique properties. Superconductors are metals whose resistivity suddenly drops at low temperature; similarly, superfluids are liquids or gases whose viscosity is much lower than in normal fluids. These phenomena rely on the same physical mechanism: at low temperature, the particles, instead of being distinguishable little balls, gather in a condensate, a quantum wave as big as the whole system. In systems made of fermionic particles (that is particles that cannot occupy the same quantum state, which include electrons, neutrons, protons and many atom nuclei), condensation may occur only if the particles first pair up. This kind of pair condensates are found in many different fields of physics, from solid-state physics with superconductors, to astronomy with neutron stars, and their study is equally crucial to the understanding of the fundamental laws of physics, and to the development of new technologies. I will try to better understand how these fermionic condensates in superconductors react to external perturbations, for instance laser pulses, with a special focus on the case when the perturbation has enough energy to break the pairs. Understanding this behavior will help predict the properties of the system as a function of temperature, and may help explain why some materials maintain their superconducting properties at higher temperatures than others.
Date:1 Mar 2020 →  28 Feb 2023
Keywords:SUPERFLUIDITY, SUPERCONDUCTIVITY
Disciplines:Atomic physics, Magnetism and superconductivity, Degenerate quantum gases and atom optics