4.

(a, b) Experimentally measured transconductance versus B _⊥ of two QPCs in a WSe₂/BLG heterostructure (sample A) at 10 mK. The left QPC (a) is the same device shown in Figure . The right QPC (b) is located on the same heterostructure stack but exhibits a different subband spectrum, likely due to differences in applied gate voltages and possible device-to-device variations. (c, d) Single-particle calculations of QPC energy levels in a BLG/WSe₂ heterostructure using DFT SOC parameters from ref with a QPC width of L = 30 nm (left) and L = 50 nm (right). The measured subband evolution, with the states of the first subband highlighted, shows good agreement with theoretical calculations. A notable deviation from the theoretical prediction is marked by an orange circle, indicating a strong bending of the 1K^– ↓ mode when crossing the 1K⁺ ↓ mode.