Multiphoton processes in the field of multimode pumping under conditions of two-photon resonance

T. U. Arslanbekov, N. B. Belone, Anatoly Viktorovich Masalov +2 more

Lü-Yun Cheng, Zi‐Liang Lan, Sai-Yun Ye +1 more

Abstract In this paper, we present a theoretical investigation of multiphoton processes between a single atom and a multimode optical or microwave field. At first, we examine two-photon excitation, which involves the simultaneous excitation of two photons in different cavity modes by a single atom. We demonstrate that when the transition frequency of an atom is equal to the sum of the frequencies of two cavity modes, there exists a resonant coupling between the atom and the two-mode cavity field, which leads to the simultaneous excitation of the two cavity photons with the atom initially in its excited state. Moreover, we found that this coupling is coherent and reversible, allowing the atom initially in the ground state to simultaneously absorb all the photons from the cavities and transit to its excited state. Finally, we also show that this coherent interaction, in principle, can be extended to describe multiphoton processes between a single atom and a multimode cavity field, such as a three-mode cavity. The parameters used in the numerical simulation are based on the experimentally demonstrated values in circuit quantum electrodynamics systems.

P. Zoller

The author presents a theory of resonant multiphoton ionisation by multimode laser light. He investigates N photon resonant N+1 photon ionisation for a high order bound-bound transition with the resonance dominated by the Stark shift. Two aspects of the problem are considered. He studies the bandwidth dependence for the resonant ionisation probability, approximating the multimode laser light by a chaotic field. Secondly, he investigates the effects of finite mode numbers of the multimode laser. Finally, the theory is compared with the recent experimental results of Lompre et al (1981).

A. T. Georges, P. Lambropoulos

Michele Crance

Viktor E. Peet, Sergei Shchemeljov

Two-color excitation by spatially coherent and incoherent laser beams has been used to study three-photon-resonant excitation and subsequent ionization of xenon in conditions, when internally generated sum-frequency field plays an important role in excitation of atomic resonances through interfering one-photon excitation pathway. We show that the incoherence in one of the pumping fields reduces the efficiency of generated sum-frequency field, and thus suppresses the interference between the three- and the one-photon excitation channels. The degree of suppression is controlled by varying the crossing angle between coherent and incoherent laser beams. We show that ionization profiles can be analyzed on the basis of the well-studied interference of one- and three-photon transition amplitudes, but with pumping field decomposed into multiple small-scale uncorrelated domains where coherent process of four-wave mixing occurs. The gain length for a coherent process in these domains depends on the coherence degree and excitation geometry. It gives a possibility of controlling the contribution of coherent processes to the excitation of multiphoton resonances.