Final Activity Report Summary - EDUG (Effects of disorder in ultra-cold gases)
This project was devoted to the study of ultra-cold atomic gases subject to random potentials. We have considered both the case of bosonic and fermionic atoms. In the presence of attractive interactions fermionic atoms can bind in Cooper pairs and become superfluids. When the interaction strength is enhanced (by tuning the scattering length near a Feshbach resonance), these pairs progressively transform into artificial molecules following Bose statistics and can therefore undergo Bose-Einstein condensation.
An important goal of my project was then to investigate how disorder affects superfluidity and condensation of pairs as the interaction strength is enhanced and molecules are formed. The main results of this study have been published in a first class international journal. There I showed that Fermi superfluids with resonant interactions are the most stable against disorder. Moreover, I explicitely showed that the superfluid order parameter is affected by impurities as the interaction strength increases, pointing out that Anderson's celebrated theorem is only valid for sufficiently weak interactions.
The problem of disorder in interacting Bose gases is also extremely rich and interesting. A considerable effort has been devoted to build a theory describing the localisation of Bogoliubov excitations induced by the disorder. This allows me to systematically compute measurable correlations functions, which is my final goal.
In the framework of an international collaboration, I have also obtained new exact results for the energy absorption spectrum of disordered one dimensional bosons in a periodically modulated optical lattice.
An important goal of my project was then to investigate how disorder affects superfluidity and condensation of pairs as the interaction strength is enhanced and molecules are formed. The main results of this study have been published in a first class international journal. There I showed that Fermi superfluids with resonant interactions are the most stable against disorder. Moreover, I explicitely showed that the superfluid order parameter is affected by impurities as the interaction strength increases, pointing out that Anderson's celebrated theorem is only valid for sufficiently weak interactions.
The problem of disorder in interacting Bose gases is also extremely rich and interesting. A considerable effort has been devoted to build a theory describing the localisation of Bogoliubov excitations induced by the disorder. This allows me to systematically compute measurable correlations functions, which is my final goal.
In the framework of an international collaboration, I have also obtained new exact results for the energy absorption spectrum of disordered one dimensional bosons in a periodically modulated optical lattice.