Si:P as a laboratory analogue for hydrogen on high magnetic field white dwarf stars

Laboratory spectroscopy of atomic hydrogen in a magnetic flux density of 105 T (1 gigagauss), the maximum observed on high-field magnetic white dwarfs, is impossible because practically available fields are about a thousand times less. In this regime, the cyclotron and binding energies become equal. Here we demonstrate Lyman series spectra for phosphorus impurities in silicon up to the equivalent field, which is scaled to 32.8 T by the effective mass and dielectric constant. The spectra reproduce the high-field theory for free hydrogen, with quadratic Zeeman splitting and strong mixing of spherical harmonics. They show the way for experiments on He and H2 analogues, and for investigation of He2, a bound molecule predicted under extreme field conditions. Measuring atomic spectra in high magnetic fields is important for understanding astrophysical objects such as white dwarfs, but laboratory fields are too small to do so. Murdin et al. study the analogous spectra of phosphorous-doped silicon, whose material properties scale the equivalent field to far lower values.