Topological Quantization in Superconducting Arrays

摘要: Two-dimensional arrays of superconducting grains, weakly coupled by Josephson junctions, provide interesting model systems for the study dynamical behaviors as well phase transitions [1], which are largely characterized vortex configuration and dynamics. In particular, junctions with small capacitances, where charging energy may not be neglected [1, 2], allow to quantum dynamics at macroscopic level; Here frustration can introduced only applying magnetic fields but also inducing external charges on leading vortices [3]. Such have been shown exhibit very dynamic responses applied currents: appropriate limits dc component voltage or that current quantized, displaying plateaus in current-voltage characteristics. Those plateaus, called giant Shapiro steps [4, 5] inverse steps, respectively, generalizations standard [6] Bloch oscillation [7, 8] previously considered a single junction. These together Hall effect, possibility has pointed out array [9], suggest three types quantization between current, voltage, their frequency.