The tunnelling conductance G is plotted as a function of the dc-bias Vdc and in-plane magnetic field B perpendicular to the wires, for the regime of a single 1D subband filled, achieved by setting the wire–gate voltage to Vwg=−0.69 V. The electron density in the wires is n1D≅35 μm−1. The solid (dashed) green lines mark resonances corresponding to tunnelling between upper-well wire W (lead L) ground states and lower-well states; they reveal the dispersion of the elementary excitations in the 2D lower well, in the wire (lead) regions of the device. The dash-dotted green lines mark resonances corresponding to tunnelling between LW ground states and UW lead states; they reveal the dispersion of the elementary excitations in the 2D UW leads. The resonances marked by the black and white arrows correspond to tunnelling from LW ground states to UW wire states; they reveal dispersions of elementary excitations in the 1D UW wires: a holon band in the particle sector (h+), and spinon bands in the hole (s−) and particle (s+) sectors. The labels ±BW,L+ indicate specific magnetic field values at which W and L tunnelling resonances cross the Vdc=0 axis.