Persistent Edge Current In the Fractional Quantum Hall Effect

We study the persistent edge current in the fractional quantum Hall effect. We give the grand partition functions for edge excitations of hierarchical states coupled to an Aharanov-Bohm flux and derive the exact formula of the persistent edge current. For $m$-th hierarchical states with $m>1$, it exhibits anomalous oscillations in its flux dependence at low temperatures. The current as a function of flux goes to the sawtooth function with period $\phi_0/m$ in the zero temperature limit. This phenomenon provides a new evidence for exotic condensation in the fractional quantum Hall effect. We propose experiments of measuring the persistent edge current to confirm the existence of the hierarchy.