Testing a state preparation and read-out protocol for the vortex qubit

A double-well potential for a Josephson vortex can be formed by applying an external magnetic field in the plane of a heart-shaped long Josephson junction. At low enough temperatures, such a system is expected to behave as a quantum two-state system and hence is a candidate for a qubit. We have designed a model system of such a vortex qubit and experimentally demonstrate here a protocol for the preparation and read-out of its states in the classical regime. The measurement results agree well with the theoretical analysis of the vortex dynamics.