Controlled equilibration between an integer and a fractional counter-propagating edge modes

Edge reconstruction occurs at the edges of a two-dimensional electron gas placed at the hole-conjugate filling factor in the fractional quantum Hall effect regime. Such is the case of filling factor 2/3, predicted to realize as two counter propagating edges; downstream filling factor 1 edge-mode and an upstream 1/3 edge-mode. However, experiments have shown equilibration between the edges takes place leading to reconstruction of the edge density profile manifesting counter propagating edges of a downstream 2/3 current edge accompanied by an upstream neutral edge.
Here, we present a new and controlled approach for observing edge reconstruction between integer and fractional counter propagating edges, such as the case of the 2/3, as a function of the interaction strength. This novel platform is based on a carefully designed double-quantum-well structure in a GaAs heterostructure, hosting two electronic sub-bands; each tuned to the quantum Hall effect regime. By gating different areas of the structure, counter-propagating integer and fractional edge modes are formed, were the equilibration between the edges is controlled via temperature, bias and magnetic field.