Phase-sensitive transport at a normal metal-superconductor interface close to a Josephson junction

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Phase- and voltage bias-sensitive quasiparticle transport at a double NIS₁IS₂ interface is considered. The barriers I range from tunnel to transparent, and the intermediate region S₁ has a width comparable to the superconducting coherence length. A phase difference φ is applied to the Josephson junction S₁IS₂. The normal and Andreev reflections at the NIS₁ interface become φ-sensitive, and transport is governed by interferences within the narrow S₁ region, both in the normal and anomalous channels. The subgap conductance is separately (energy E)- and (phase φ)- symmetric. Above the superconducting gap, the conductance is in general not symmetric even if (E,φ) is changed in (-E,-φ), but the symmetry is restored by averaging Fermi oscillations. The Tomasch oscillations are amplified by the phase difference. The subgap conductance exhibits a resonant structure at the energy of the Andreev bound states (ABS) of the S₁IS₂ junction, providing a side-spectroscopy of such states. Depending on the relative transparencies of the junctions, the resonance can increase or reduce the conductance, and it can even vanish for φ=π, featuring total reflection of quasiparticles at NS₁ by the ABS at S₁S₂.