PRICE, A.N. ... et al, 2010. Vortex qubit based on an annular Josephson junction containing a microshort. Physical Review B, 81 (014506), 12pp.
We report theoretical and experimental work on the development of a vortex qubit based on a microshort in
an annular Josephson junction. The microshort creates a potential barrier for the vortex, which produces a
double-well potential under the application of an in-plane magnetic field; the field strength tunes the barrier
height. A one-dimensional model for this system is presented, from which we calculate the vortex-depinning
current and attempt frequency as well as the interwell coupling. Implementation of an effective microshort is
achieved via a section of insulating barrier that is locally wider in the junction plane. Using a junction with this
geometry we demonstrate classical state preparation and readout. The vortex is prepared in a given potential
well by sending a series of “shaker” bias-current pulses through the junction. Readout is accomplished by
measuring the vortex-depinning current.