Low-energy quasiparticle transport through Andreev levels

We measure the resistance of a normal mesoscopic sample with two Supercondu cting mirrors and find two regimes with qualitatively different behavior. A t temperatures below 90 mK peaks in the conductance were found when the pha se difference between the two superconductors is an odd multiple of rr. The peak heights increase with decreasing temperature. Above 100 mK the observ ed peaks give way to dips in the conductance. While the high-temperature be havior can be explained in terms of the thermal effect [Phys. Rev. Lett, 76 , 823 (1996)], we propose that the low-temperature behavior is: a manifesta tion of resonant transmission of low-energy quasiparticles through Andreev states. [S0163-1829(99)11641-2].