  We propose a way to control the Josephson energy of a single Josephson
junction embedded in one- dimensional superconducting metamaterial: an
inhomogeneous superconducting loop, made out of a superconducting nanowire or a
chain of Josephson junctions. The Josephson energy is renormalized by the
electromagnetic modes propagating along the loop. We study the behaviour of the
modes as well as of their frequency spectrum when the capacitance and the
inductance along the loop are spatially modulated. We show that, depending on
the amplitude of the modulation, the renormalized Josephson energy is either
larger or smaller than the one found for a homogeneous loop. Using typical
experimental parameters for Josepshon junction chains and superconducting
nanowires, we conclude that this mode-engineering can be achieved with
currently available metamaterials.
