# Population transfer at exceptional points in spectra of the hydrogen atom in parallel electric and magnetic fields. (arXiv:1802.01443v1 [quant-ph])

time-dependent loop around exceptional points in spectra of the hydrogen atom

in parallel electric and magnetic fields. Exceptional points are well-suited

for population transfer mechanisms, since a closed loop around these in

parameter space commutes eigenstates. We address the question how shape and

duration of the dynamical parameter loop affects the transferred population, in

order to optimize the latter. Since the full quantum dynamics of the expansion

coefficients is time-consuming, we furthermore present an approximation method,

based on a $2\times 2$ matrix.