The Evolution from BCS to BEC Superfluidity in Multiband Systems: Applications to Two-band Superconductors and Ultra-cold Fermi Gases

by Carlos A. R. Sa de Melo (Georgia Institute of Technology - Atlanta, GA, USA)

Tuesday 25 Feb 2020, 16:00 → 18:00 Europe/Rome

Sala Lauree (Dip. di Fisica - Edificio G. Marconi)

The Evolution from BCS to BEC Superfluidity in Multiband Systems: Applications to Two-band Superconductors and Ultra-cold Fermi Gases Abstract = I discuss the evolution from Bardeen-Cooper Schrieffer (BCS) to Bose-Einstein Condensate (BEC) superfluids in three-dimensional s-wave two-band superfluids with a possible Josephson coupling between bands. When the Josephson coupling is tuned from negative to positive values a quantum phase transition occurs, and population imbalances between the two bands can be created by tuning the band offset or intraband and interband interactions. Then, I obtain the resulting coupled Ginzburg-Landau equations and show that they reduce to coupled Gross-Pitaevskii equations for two types of bosons in the BEC limit. Lastly, I present results for two-dimensional d-wave two-band systems.