The Josephson effect through the BCS-BEC crossover
speaker: Andrea Spuntarelli (UNICAM - Università di Camerino - Italy)abstract: We study the stationary Josephson effect for a system of neutral fermions with a mutual attractive interaction, that ranges from weak to strong coupling across the BCS-BEC crossover, by solving numerically the Bogoliubov-de Gennes equations for several types of barriers with an imposed current at zero temperature. Implementing self-consistency in the calculation proves essential, especially on the BEC side of the crossover where we recover a description of composite bosons in terms of the Gross-Pitaevskii equation. We show that the maximum Josephson current as a function of coupling occurs for all barriers at about unitarity. In addition, in the limit of vanishing barrier height, this maximum approaches the value obtained by the Landau criterion which, depending on the coupling, is determined by either pair-breaking or sound-mode excitations. An experiment is suggested to identify the evolution of this maximum value through the crossover. Approx. duration
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