Exotic odd–even parity effects in transmission phase, (Andreev) conductance, and shot noise of a dimer atomic chain by topology

Abstract

We investigate the transport properties through a finite dimer chain connected to two normal leads or one normal and one superconductor (SC) leads. The dimer chain is described by the Su–Schrieffer–Hegger model and can be tuned into a topologically nontrivial phase with a pair of zero-energy edge states (ZEESs). We find that if the dimer chain is of nontrivial topology, (1) it will show opposite odd–even parity of the number of sites, in comparison with the topologically trivial and plain chains, in the (Andreev) transmission probability at the Fermi energy, the noise Fano factor in the zero bias limit, and even the transmission phase due to the coupled ZEESs; (2) the ZEES can determine appearance of the Andreev bound states at the site connected to the SC lead, and thereby induces a nonzero-bias-anomaly in the Andreev differential conductance of the hybrid junction; (3) the transmission phase of the normal junction has a unique 2π continuous phase variation at the zero-energy resonant peak that is also different from the usual phase shift in resonant point in usual systems.