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arXiv · 2608.09562

Conditional non-Hermitian acceleration of multiphoton atomic transitions

Marcos V. S. de Paula·Alexandre P. Costa·A. V. Dodonov
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Abstract

Continuous monitoring can convert a dissipative channel into a resource for accelerating otherwise slow multiphoton transitions. We consider a three-level atom in a $\Lambda$ configuration and condition the evolution on the absence of photon emission through an auxiliary monitored decay channel. The resulting no-jump dynamics is governed by a non-Hermitian Rabi-type Hamiltonian. Using Floquet theory and Brillouin--Wigner projection-operator perturbation method, we derive effective two-state descriptions of odd-multiphoton resonances in the semiclassical and quantum Rabi models. The effective population-transfer rate, defined as the inverse of the time required for the first complete transfer between the atomic states, is maximized at an exceptional point, where its enhancement factor approaches $\pi/2$, corresponding to an approximately $57\%$ increase over the Hermitian value. Numerical results for three- and five-photon resonances closely reproduce the analytical transition times and yield non-negligible postselection probabilities. By contrast, the complete unconditioned dissipative evolution does not exhibit the same population-transfer enhancement. These results demonstrate a speed--success trade-off for measurement-conditioned multiphoton state transfer.

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Marcos V. S. de Paula, Alexandre P. Costa, A. V. Dodonov. 2026-08-10. Conditional non-Hermitian acceleration of multiphoton atomic transitions. https://arxiv.org/abs/2608.09562

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