David Pekker

(University of Pittsburgh)

 Mesoscopics with attractive electrons

I will describe two mesoscopic systems in which attractive electron-electron interaction result in two unusual, and perhaps unexpected, features: Andreev blockade and Pascal-liquid phases.

The first system, is a double quantum dot systems with one normal metal lead and one superconducting lead. This system can support electron transport via Andreev tunneling, in which an electron from the double quantum-dot system is reflected as a hole and a Cooper pair is formed in the superconducting lead. As Cooper pairs are spin-singlets, a low energy spin-triplet state on the double quantum dot system cannot undergo Andreev reflection, resulting in a new type of blockade phenomenon which we call Andreev blockade.

The second system, is a quasi-one dimensional electron waveguide (sketched into LAO/STO heterostructure) with attractive electron electron interactions. Experimental conductance data shows a series of conductance plateaus at {1, 3, 6, 10, …}e^2/h (second diagonal of the Pascal triangle). We show, using DMRG calculations, that these plateaus can be naturally associated with quantum liquids of electrons, electron pairs, electron trions, etc.