Parameter estimation in atomic spectroscopy using exceptional points

We suggest a method for accurate parameter estimation of atomic systems, employing the special properties of the exceptional points. The non-Hermitian degeneracies at the exceptional points emerge from the description of the spontaneous emission of the atomic system in the framework of an open quantum system, resulting in a non-Hermitian quantum master equation. The method is demonstrated for the atomic spectrum of S →P transitions of ⁸⁵Rb and ⁺⁴⁰Ca.