Tunable pseudogaps due to nonlocal coherent transport in voltage-biased three-terminal Josephson junctions

We investigate the proximity effect in junctions between N=3 superconductors under commensurate voltage bias. The bias is chosen to highlight the role of transport processes that exchange multiple Cooper pairs coherently between more than two superconductors. Such nonlocal processes can be studied in the dc response, where local transport processes do not contribute. We focus on the proximity-induced normal density of states that we investigate in a wide parameter space. We reveal the presence of deep and highly tunable pseudogaps and other rich structures. These are due to a static proximity effect that is absent for N=2 and is sensitive to an emergent superconducting phase associated to nonlocal coherent transport. In comparison with results for N=2, we find similarities in the signature peaks of multiple Andreev reflections. We discuss the effect of electron-hole decoherence and of various types of junction asymmetries. Our predictions can be investigated experimentally using tunneling spectroscopy.