Tunnel-coupled one-dimensional electron systems with large subband separations

One-dimensional (1D) ballistic electron transport is studied through nearly identical stacked 1D quantum conductors separated by a thin tunneling barrier. In contrast to previous works, the 1D electron systems are prepared to exhibit large 1D subband spacings of more than 10 meV. Degeneracies of 1D subbands of equal lateral mode index are lifted and show energy splittings of up to 5.4 meV between symmetric and antisymmetric states. This allows an unprecedented resolution in longitudinal magnetotransport spectroscopy which leads to the observation of an oscillatory mode-dependent variation in the anticrossings of 1D-subband edges of equal lateral mode index.