Chirp asymmetry in Zeeman electromagnetically induced transparency

The simplest three-level system exhibiting electromagnetically induced transparency (EIT) exhibits an effective conjugation symmetry as well as a transposition symmetry. Breaking the conjugation symmetry leads to a distinct chirp asymmetry, i.e., the differential response to a frequency increase versus a frequency decrease. The dynamic range of the many tunable optical parameters of the Hanle–Zeeman EIT resonance makes it an ideal platform for testing the chirp asymmetry’s dependence on the CP-breaking parameter and broadening. We describe the theory and compare it to an experiment using 87 Rb in a buffer gas cell. In contrast with earlier multi-photon chirp asymmetry work, this present effort explores the asymmetry at nearly one-billionth the earlier chirp rate and fully explores its universal features. The chirp asymmetry may have metrological consequences for understanding systematic dependence on modulation/demodulation parameters.