2026/07/29 by Aida Shiroyan, Genko S. Vasilev, Nikolay V. Vitanov
Physics and Astronomy · #quant-ph
14 pages, 5 figures
arxiv created 2026/07/29 · arxiv updated 2026/07/31
We study the coherent excitation of a two-state quantum system by a field with a Lorentzian temporal envelope and constant carrier frequency. The associated differential equation admits an exact local representation in terms of confluent Heun functions. For the transition probability we develop a Dykhne-Davis-Pechukas (DDP) description based on the two relevant complex transition points and their interference. The DDP action is analyzed directly in the weak- and strong-coupling limits, yielding explicit asymptotic expressions for the oscillation phase, oscillation envelope, far-detuned line shape, and near-resonant behavior. In particular, the strong-coupling asymptotics imply a linewidth proportional to the inverse peak Rabi frequency for resonant odd-π pulses, thereby exhibiting the power-narrowing characteristic of the Lorentzian pulse.