[en] The multiphoton ionization of hydrogen by a laser with a short temporal pulse and a high peak intensity is calculated using the Strong Field Approximation method. Both circular and linear polarizations of the laser are considered, and energy spectra and photoionization yields are presented. Calculations are made for pulses as short as a single wave period of the laser

No abstract available

[en] We discuss a comment recently made by C F Lo concerning validity of one of the examples used in our paper (2013 J. Phys. A: Math. Theor. 46 235301). While we agree with Lo’s statement regarding inapplicability of the example to the proposed schema, we disagree with the claim concerning mathematical correctness of that example. We are not convinced by Lo’s arguments leading to the conclusion that the model is mathematically ill-defined. (reply)

[en] We obtain the exact analytical results of all the eigenvalues and eigenstates for three kinds of models describing N-mode multiphoton process without using the assumption of the Bethe ansatz. The exact analytical results of all the eigenstates and eigenvalues are in terms of a parameter λ for three kinds of models describing N-mode multiphoton process. The parameter is shown to be determined by the roots of a polynomial and is solvable analytically or numerically. Moreover, these three kinds of models can be processed with the same procedure.

[en] Highlights: • IRMPD of C2, C3 and C4 nitroalkanes and alkyl nitrites is studied. • DC slice imaging is used as state-resolved probe of NO product. • Trends in translational energy are correlated to NO J level for nitro systems. • Distinct behavior is seen for C4 systems vs. C2 and C3. • Roaming-mediated isomerization is suggested as the mechanism for C2 and C3 case. We present a DC slice imaging study of the decomposition of C2, C3 and C4 nitroalkanes and alkyl nitrites, focusing on the NO elimination channel, possibly a minor pathway. Infrared multiphoton dissociation (IRMPD) is used to induce dissociation on the ground electronic state under collisionless conditions. The channels that produced NO as a product were studied and compared among the target molecules to gain a better understanding of the isomerization of the nitroalkanes prior to dissociation. Trends in the total translational energy and NO rotational temperatures obtained from the images are discussed.

[en] We investigate the squeezing properties of the cavity field in the degenerate two-photon Jaynes-Cummings model. Compared with the one-photon Jaynes-Cummings model, the squeezing is more pronounced in the case of two-photon Jaynes-Cummings model under certain conditions.

[en] Motivated by recent results in multiphoton interferometry, we expand a result of Kostant on immanants of an arbitrary m × m unitary matrix $T\in <!--\; ???\; -->\mathrm{S}\mathrm{U}(m)$ to the submatrices of T. Specifically, we show that immanants of principal submatrices of a unitary matrix T are a sum ${{\displaystyle \sum <!--\; ???\; -->}}_t{D}_{tt}^{(\mathrm{\lambda <!--\; ??\; -->})}(\mathrm{\Omega <!--\; ??\; -->})$ of the diagonal D-functions of group element Ω, with t determined by the choice of submatrix, and the irrep (λ) determined by the immanant under consideration. We also provide evidence that this result extends to some submatrices that are not principal diagonal, and we discuss how this result can be extended to cases where T carries an SU(m) representation that is different from the defining representation. (letter)

[en] A nonperturbative treatment of the multiphoton ionization of the hydrogen atom based on the S matrix and devised for nonresonant strong-field situations is analyzed in the weak-field limit. Comparisons are presented with other S matrices as well as other nonperturbative approaches. Our treatment is found to perform generally better than similar S-matrix treatments. The usual perturbative results are recovered provided that the photon wavelengths are sufficiently short and are off resonance with the atomic transitions. Important indications are obtained as to the role of the atomic structure, the relevance of the gauge consistency, and the reliability and improvement of the present nonperturbative treatment. The results represent a significant step toward an assessment of the S-matrix-based treatments of multiphoton ionization

[en] Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement.

[en] A system of a three-level atom interacting with single mode cavity field through multi-photon transition in the presence of a Kerr-like medium is proposed, and its pseudo-invariant eigen-operator (PIEO) and energy-level gap are presented under one-order approximation