Magnetic Flux Quanta in YBCO Thin Film Loop Controlled with Femtosecond Optical Pulses

Abstract

We have demonstrated a magnetic flux control in a YBCO thin film loop with femtosecond (fs) optical pulses. We employed a supercurrent modulation technique to control the magnetic flux quanta in the superconductive loop. The results revealed that the optical pulses can create and annihilate the flux quanta with the polarity controlled in the loop, and the amount of the flux can be controlled by the bias current. We discuss the mechanism for the readin of the magnetic flux quanta in the loop, and also report the visualization technique of the trapped magnetic flux with the THz radiation mapping.