Condensed Matter Seminar Series

Y-junctions of quantum wires

Claudio Chamon

Boston University

Thursday October 16, 1:30 pm, Room 234, Physics Building

Abstract: The integration of nanometer-scale devices requires junctions of nanowires that distribute signals among the circuit components. In contrast to wire junctions at the millimeter and micron scale, quantum and electron interaction effects must be fully taken into account at the nano scale. This problem of quantum wire junctions is an extremely rich one, with many basic science issues and connections to other branches in Physics. Here we study a junction of three quantum wires enclosing a magnetic flux. This is the simplest problem of a quantum junction between Tomonaga-Luttinger liquids in which Fermi statistics enter in a non-trivial way. We present a direct connection between this problem and the dissipative Hofstadter problem, or quantum Brownian motion in two dimensions in a periodic potential and an external magnetic field, which in turn is connected to open string theory in a background electromagnetic field. We find non-trivial fixed points corresponding to a chiral conductance tensor leading to an asymmetric flow of the current.