Andreev scattering in the asymmetric ladder with preformed bosonic pairs

We discuss the phase coherence that emanates from the ladderlike proximity effect between a weak superconductor with preformed bosonic pairs (here, a single-chain Luther-Emery liquid with superconducting correlations that decay approximately as x(-1)) and a Fermi ga's with unpaired fermions. Carefully studying tunneling mechanism(s), we show that them boson-mediated Cooper pairing between remaining unpaired electrons results in a quasi-long-range superconductivity: Superconducting correlations decay very slowly as x(-eta) with eta approximate to1/2. This process is reminiscent of the coupling of fermions to preformed bosonic pairs introduced in the context of high-T-c cuprates.