From vortices to genomics

摘要

A basic property of superconductors, besides their lack of electrical resistance, is the ability to exclude magnetic fields from their interior so long as the applied field does not exceed a critical value H_c. In the case of type-Ⅱ superconductors, which include the high-T_c materials, screening of external fields is only partial, with magnetic flux penetrating the interior in the form of vortex lines below a lower critical field H_(c1). Previous research in this area has focused on the collective behaviour of large numbers of vortex lines. Now, on page 43 of this issue, Bolle et al. report observations of the kinetics and thermodynamics of individual vortex lines threaded through a planar type-Ⅱ superconductor. A series of fascinating discrete 'events' is observed close to the lower critical field H_(c1), where a small number of vortex lines are present in the sample. The findings are comparable to 'mesoscopic' electronic systems (typically a micrometre or less in size), where interesting effects such as Coulomb blockade and universal conductance fluctuation occur when the quantization of electronic charge becomes important in a small volume.