We show that in the limit of zero temperature, double-layer quantum Hall systems exhibit a phenomenon called Hall drag, namely, a current driven in one layer induces a voltage drop in the other layer, in the direction perpendicular to the driving current. The two-by-two Hall resistivity tensor is quantized and proportional to the K matrix that describes the topological order of the quantum Hall state, even when the K matrix contains a zero eigenvalue, in which case the Hall conductivity tensor does not exist. The relation between the present work and previous ones is also discussed.

• Received 12 May 1998

DOI:https://doi.org/10.1103/PhysRevB.58.R4246