The presence of interlayer coherence in bilayer quantum Hall states was examined by magnetotransport experiments. Two macroscopic quantum conjugate observables, the phase difference and the electron density difference between the two layers, are experimentally addressed by tilting the sample in a magnetic field and applying gate bias voltages. Results strongly indicate the presence of interlayer coherence at the filling factor $\nu =1\mathrm{}$ and 2.

• Received 16 March 1999

DOI:https://doi.org/10.1103/PhysRevB.59.14888