Brandon's Semiconductor Simulator (opens in new tab)

I don't pretend to know what this simulation is doing, but for the record, electromagnetism works just fine in 2D. You might be thinking "but magnetic fields are intimately tied to cross products, which only work in three dimensions." But you can set up the equations of electromagnetism just fine either using differential forms or bivector magnetism (https://arxiv.org/abs/2309.02548), and it works in any dimension you'd like. (The cross product version is really a narrow and sometimes misleading special case.)

Possibly related: there are options to "View B" and "View H" in the scalar dropdown, not in the vector one. That may be closely related to the fact that in two dimensions, the magnetic field has just a single component. Whether you describe is as a 2-form or a bivector, the magnetic field is an antisymmetric rank-2 tensor: an antisymmetric matrix. In 3D, that means 3 independent components, and there's a one-to-one mapping to vectors (more or less). But in 2D, an antisymmetric matrix has just one independent component. (And in 4D, it's got six: this is precisely the relativistic electromagnetic field tensor, that in 3D splits into an electric part and a magnetic part. My paper has more details.)

cefFlashbrowser can do it better

Brandon here. I was very much inspired by Falstad's applets. I had him take a look at my simulation and he generously offered to make a JS port.

Thanks, quite the useful simulator; I hadn't found that page yet. Additional considerations for circuit simulators:

What does the simulator say about signal delay and/or propagation in electronic circuits and their fields? How long does it take for a lightbulb to turn on after a switch is thrown, given the length of the circuit and the real distance between points in it?

(I learned this gap in our understanding of electron behavior from this experiment, which had never been done FWIU: "How Electricity Actually Works" (2022) https://www.youtube.com/watch?v=oI_X2cMHNe0 )

FWIW, additionally:

Hall Effect and Quantum Anomalous Hall Effect;

"Tunable superconductivity and Hall effect in a transition metal dichalcogenide" (2025) https://news.ycombinator.com/item?id=43347319

ScholarlyArticle: "Moiré-driven topological electronic crystals in twisted graphene" (2025) https://www.nature.com/articles/s41586-024-08239-6

NewsArticle: "Anomalous Hall crystal made from twisted graphene" (2025) https://physicsworld.com/a/anomalous-hall-crystal-made-from-...

From "Single-chip photonic deep neural network with forward-only training" https://news.ycombinator.com/item?id=42314581 :

"Fractional quantum anomalous Hall effect in multilayer graphene" (2024) https://www.nature.com/articles/s41586-023-07010-7

"Coherent interaction of a-few-electron quantum dot with a terahertz optical resonator" (2023) https://arxiv.org/abs/2204.10522 .. https://news.ycombinator.com/item?id=39365579

> "Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework" (2024) https://www.science.org/doi/10.1126/sciadv.adi3147

Electrons (and photons and phonons and other fields of particles) are more complex than that though.