Critical current diffraction patterns for annular Josephson
junctions in dependence of the direction of the field

A.Kemp, A.Wallraff, Yu. Koval, M. Levitchev, M.V. Fistul and A.V. Ustinov

Detailed experimental investigation of critical current patterns for
annular Josephson junctions in dependence on the external magnetic
field is reported.  The in-plane field was applied in all possible
directions. Junction's states with and without fluxons have been
measured. Our ultimate goal is to engineer the magnetic field-induced
potential for a fluxon by shaping the junction and controlling the
magnetic field direction in its plane.  We expect to observe
distinctly different depinning currents that correspond to various
metastable fluxon states prepared in a controlled way. Once under
control, this technique can be used for performing a macroscopic
quantum coherence experiment with a single fluxon.