Tunneling spectroscopy in vertically coupled quantum wires

Tunneling between independently contacted weakly coupled quantum wires provides insight into the nature of interactions in one-dimensional systems. The double quantum wires used here are defined using a combination of gates both above and below an electron bilayer to create and make separate contact with the wires. This split-gate technique has the advantage of independent control over the density of each of the quantum wires. Tunneling measurements are performed as a function of both a voltage bias between the wires as well as an in-plane magnetic field. These external parameters alter the energy and momentum of the tunneling electron, and therefore provide complete spectroscopic information about tunneling events in 1D. Evidence for tunneling between wires with multiple subbands is presented. Our results can be well described using a model of non-interacting tunneling in 1D.