Condensed Matter Seminar Series

Path Integral Studies of Quantized Conductance and Luttinger Liquid Behavior in GaAs Nanostructures

John Shumway

Arizona State University

Thursday February 12,  11:00 am,  Room 298,  Physics Building

Abstract: We are developing new quantitative tools for studying many-body transport in nanostructures. There is a real need for new theories for transport in nanostructures, since most practical calculations focus on single-particle transport, and field-theoretic ideas such as Luttinger liquid theory are more applicable to extended systems than nanostructures. We have used path integral Monte Carlo to simulate more than 100 interacting electrons in quantum wires and quantum point contacts at temperatures as low as 750 mK. We see different phases of electrons, corresponding to two-dimensional Fermi liquids and Wigner crystals and one-dimensional Luttinger liquids. Using the Kubo formalism, we see quantized conductance plateaus at multiples of the conductance quantum. From the same current-current correlation functions we measure different velocities for spin and charge waves. In quantum point contacts we simulate a reservoir of around a split-gate channel, and see spin and charge ordering within the channel as the gates pinch off. I will finish the talk with a summary of the strengths and weaknesses of this computational approach and challenges for ab initio calculations for molecular electronics.