Dispersion of the Excitations of Fractional Quantum Hall States

Abstract

Getting Below the Surface Two-dimensional electron systems have proved to be a productive area for the study of low-dimensional transport. Despite decades of intense effort, the actual dispersion of the electronic excitations—how their energy behaves as a function of momentum as the they move through their two-dimensional space—have eluded experiments. This elusiveness is due to the samples being thin and buried. Kukushkin et al. (p. 1044; published online 30 April; see the Perspective by Simon ) now introduce a technique based on launching surface acoustic waves through the sample. The excitations “ride” these waves, with their energy and momentum mapped out using pulses of laser light. The technique should also be applicable to other hard-to-get-at electronic systems.