Abstract
We design, fabricate, and study a hole bilayer in a strained germanium double quantum well. Magnetotransport characterisation of double quantum well field-effect transistors as a function of gate voltage reveals the population of two hole channels with a high combined mobility of 3.34×10⁵ cm²/Vs and a low percolation density of 2.38×10¹⁰ cm⁻². We resolve the individual population of the channels from the interference patterns of the Landau fan diagram. At a density of 2.0×10¹¹ cm⁻² the system is in resonance and we observe an anti-crossing of the first two bilayer subbands characterized by a symmetric-antisymmetric gap of ∼0.69 meV, in agreement with Schr\"odinger-Poisson simulations.