HYPERFINE

Migratory birds may sense Earth's magnetic field through a short-lived pair of radicals inside the cryptochrome protein of the retina. Hyperfine lets you explore that idea directly. It computes the spin dynamics of a flavin–tryptophan radical pair on your device, in real time. SPIN LAB Set the field strength (0–100 µT) and inclination, and read out the singlet recombination yield Φₛ to six decimal places. This is the quantity a radical-pair compass would depend on. COHERENCE Watch singlet ⇄ triplet quantum beats on an oscillograph at 100 ns, 1 µs and 10 µs timescales. A frequency breakdown separates the hyperfine beats from the electron Larmor frequency. A polar plot shows how the yield changes with field direction, along with the compass contrast ΔΦₛ. TENSOR Edit the principal hyperfine values (Axx, Ayy, Azz), switch between ¹⁴N and ¹⁵N with correctly rescaled couplings, and set the radical-pair lifetime and coherence time. An animated diagram shows how electron transfer along the tryptophan chain creates the pair. ATLAS A small reference library of radical-pair systems: flavin N5 and N10, the tryptophan indole N1, an isotope-labelled variant, and an isotropic textbook model. Load any of them into the lab with one tap. DESIGNED FOR IPHONE DUO On the unfolded inner display, controls and results sit side by side in two independently scrolling panes. On the cover display and on standard iPhones, everything flows into a single column. THE MODEL Hyperfine calculates the spin Hamiltonian exactly for two electrons and one magnetic nucleus, using exponential recombination kinetics. Decoherence is approximated with a single dephasing time (T₂). Hyperfine values are representative literature-order figures. Hyperfine is a tool for learning and exploration, not a research-grade multi-nucleus simulation.