OPTICS WITH QUANTUM HALL SKYRMIONS

A novel type of charged excitation, known as a Skyrmion, has recently been discovered in quantum Hall systems with filling factor near nu = 1. A Skyrmion - which can be thought of as a topological twist in the spin density of the electron gas - has the same charge as an electron, but a much larger spin. In this review we present a detailed theoreti cal investigation of the optical properties of Skyrmions. Our results provide means for the optical detection of Skyrmions using photolumine scence (PL) spectroscopy. We first consider the optical properties of Skyrmions in disordered systems. A calculation of the luminescence ene rgy reveals a special optical signature which allows us to distinguish between Skyrmions and ordinary electrons. Two experiments to measure the optical signature are proposed. We then turn to the optical proper ties of Skyrmions in pure systems. We show that, just like an ordinary electron, a Skyrmion may bind with a hole to form a Skyrmionic excito n. The Skyrmionic exciton can have a lower energy than the ordinary ma gnetoexciton. The optical signature of Skyrmions is found to be a robu st feature of the PL spectrum in both disordered and pure systems.