Proposed Design of a Josephson Diode

We propose a new type of Josephson junction formed by two superconductors close to the superconductor–Mott-insulator transition, one of which is doped with holes and the other is doped with electrons. A self-organized Mott-insulating depletion region is formed at the interface between two superconductors, giving rise to an asymmetric response of current to the external voltage. The collective excitations of the depletion region result in a novel phase dynamics that can be measured experimentally in the noise spectrum of the Josephson current.

Figure 1

The mean-field phase diagram of the Bose-Hubbard model. The left (right) side of the junction corresponds to the states at point A(B).

Figure 2

The sketch of the junction: (a) the spatial distribution of chemical potential before equilibrium is formed, (b) the Mott-insulating depletion region and charge distribution in equilibrium, (c) the potentials $V_h$ and $V_d$ for the holons and doublons across the junction, respectively.

Figure 3

The length of Mott-insulating depletion region $D$ and the Josephson coupling strength $J$ as a function of the external voltage $V_{\mathrm{ex}}$ (arbitrary unit for the vertical axis).