Fig. 1. Model of the 4D Quantum Hall lattice and its circuit implementation.

a Schematic of the 4D tight-binding model. Each unit cell consists of four sites labelled A–D. Hollow and filled circles respectively denote positive (m) and negative (−m) on-site masses, while yellow solid lines and blue dashes respectively denote positive (J) and negative (−J) hoppings. b Photographs of the circuit. c Schematic of the circuit; positive (negative) masses are realised by capacitors (inductors) connecting the sites to ground, and hoppings are realised using capacitors or inductors connecting different sites. The components shown here are C₀ = 1 nF (yellow lines), L₀ = 2 mH (blue dashes), $C^{\prime }=2\mathrm{nF}$ (purple curves), $L^{\prime }=1\mathrm{mH}$ (green curves), and C_m = 2mC₀ (grey dashes). Each site is grounded by a set of additional circuit components (see Supplementary Note 2); for clarity, only the grounding components for two sites (in the dashed red box) are depicted.