axionbloch
Bloch-equation-based simulations for axion-induced spin dynamics.
The interaction of ultralight bosonic dark matter with nuclear spins can be interpreted as a pseudomagnetic field acting on ordinary matter. axionbloch models such interactions — together with the usual magnetic interactions — using the spin-evolution (Bloch) equations, providing a numerical tool for deriving axion signal signatures that are crucial for designing experimental searches and data analysis.
The package interface is implemented in Python for simplicity and readability; the underlying RK4 numerical integration is implemented in C++ (exposed via pybind11) for computational efficiency. All inputs and outputs use SI units via astropy, making results directly comparable to experimental parameters and observables.
axionbloch supports the following axion field configurations:
Milky Way axion halo — stochastic axion wind from the Standard Halo Model, with analytical lineshapes and Monte-Carlo amplitude spectra.
Earth-bound axion halo — axions gravitationally trapped by the Earth, solved as bound states of the radial Schrödinger equation (TISE).
The package is also useful for general NMR simulations: pulse sequences, free decay, spin echoes, and CW excitation can all be configured and visualized, making axionbloch suitable for educational purposes as well.
The package is documented here and available at github.com/Yuzhe98/AxionBloch.
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