Coalescence of two branch points in complex time marks the end of rapid adiabatic passage and the start of Rabi oscillations

0559105 - FZÚ 2023 RIV GB eng J - Journal Article
Kaprálová-Žďánská, Petra Ruth - Šindelka, Milan - Moiseyev, N.
Coalescence of two branch points in complex time marks the end of rapid adiabatic passage and the start of Rabi oscillations.
Journal of Physics A-Mathematical and Theoretical. Roč. 55, č. 28 (2022), č. článku 284001. ISSN 1751-8113. E-ISSN 1751-8121
R&D Projects: GA MŠMT LTT17015; GA ČR(CZ) GA20-21179S
Institutional support: RVO:68378271 ; RVO:61389021
Keywords : physics of exceptional points * Dyhkne-Davis-Pechukas formula * Rabi oscillations * rapid adiabatic passage * chirped laser pulses * coalescence of transition points * experimental proposal
OECD category: Fluids and plasma physics (including surface physics); Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) (UFP-V)
Impact factor: 2.1, year: 2022
Method of publishing: Limited access
https://doi.org/10.1088/1751-8121/ac76f7

We study theoretically the population transfer in two-level atoms driven by chirped lasers. It is known that in the Hermitian case, the rapid adiabatic passage (RAP) is stable for an above-critical chirp below which the final populations of states Rabi oscillate with varying laser power. We show that if the excited state is represented by a resonance, the separatrix marking this critical phenomenon in the space of the laser pulse parameters emanates from an exceptional point (EP). This critical phenomenon is neatly understood via extending the 'slow' time variable into the complex plane, uncovering a set of branch points which encode non-adiabatic dynamics, where the switch between RAP and Rabi oscillations is triggered by a coalescence of two such branch points. We assert that the intriguing interrelation between the two different singularities - the EP and the branch point coalescence in complex time plane - can motivate feasible experiments involving laser driven atoms.

Permanent Link: https://hdl.handle.net/11104/0332566