We present an experimental study of the spectra produced by optical/radio-frequency double resonance in which resonant linearly polarized laser light is used in the optical pumping and detection processes. We show that the experimental spectra obtained for cesium are in excellent agreement with a very general theoretical model developed in our group and we investigate the limitations of this model. Finally, the results are discussed in view of their use in the study of relaxation processes in aligned alkali vapors.
We review on the theoretical status of intense laser orientation and alignment. The evolution of the rotational wave packet and its dynamics leading to orientation and alignment is the topic of the present discussion. The major part of the article basically presents an overview on recent theoretical progress in controlling the orientation and alignment dynamics of a molecule by means of shaped laser pulses. The various theoretical approaches that lead to orientation and alignment ranging from static electrostatic field in combination with laser field(s), combination of orienting and aligning f…
We report on a simple and robust technique to generate a dispersive signal which serves as an error signal to electronically stabilize a monomode cw laser emitting around an atomic resonance. We explore nonlinear effects in the laser beam propagation through a resonant vapor by way of spatial filtering. The performance of this technique is validated by locking semiconductor lasers to the cesium and rubidiumD2 line and observing long-term reduction of the emission frequency drifts, making the laser well adapted for many atomic physics applications.
A thermal atomic ensemble-based laser source with superior frequency stability is proposed that relies on the accumulated contributions from an abundance of nonzero-transverse-velocity atomic ensembles. Compared with the traditional case in which only atoms with near-zero transverse velocities are utilized, the amplitude of the optical Ramsey fringes for a thermal calcium beam can be dramatically enhanced by three orders of magnitude or more, thus, the signal-to-noise ratio can be improved 33-fold. Based on the recent results of atomic interferometry-based laser stabilization, a quantum projec…
We have studied the temporal behavior of the atomic absorption signal under resonant excitation with a continuous-wave laser radiation. Measurements done for D2 line of 85Rb with ~ 1 ns temporal resolution have shown irregular oscillatory behavior of the transmission signal, which becomes well pronounced for high laser power, and disappears when the laser is tuned off-resonance. Application of the fast Fourier transform analysis of the transmission signal reveals power-dependent frequency peaks, which are shown to be associated with Rabi frequency. Possible linkage of the observed results with…
We present a technique for simultaneous laser frequency stabilization on transitions of multiple atomic species with a single optical setup. The method is based on modulation transfer spectroscopy and the signals are separated by modulating at different frequencies and electronically filtered. As a proof of concept, we demonstrate simultaneous spectroscopy of the potassium D$_1$, D$_2$ and rubidium D$_2$ transitions. The technique can easily be extended to other atomic species and allows the development of versatile and compact frequency reference modules.
We report a robust method of stabilizing a laser to the frequency of an atomic transition using a hollow cathode lamp. In contrast to the standard dichroic atomic vapor laser lock (DAVLL) method, which uses dichroism induced by a longitudinal magnetic field, we employ birefringence induced by a transversal magnetic field. We applied this method to the $(5s^2)\ {}^{1}S_{0} - (5s5p)\ {}^{1}P_{1}$ transition (461 nm) of Sr. Although the hollow cathode is made of ferromagnetic material, we successfully applied a magnetic field of sufficient strength to obtain an error signal with a theoretical max…
It is generally assumed that for ionization processes, which occur in slow atomic collisions, the coupling of the colliding system to the quantum radiation field is irrelevant. Here we show, however, that -- contrary to expectations -- such a coupling can strongly influence ionization of a beam of atomic species A slowly traversing a gas of atomic species B excited by a weak laser field. Moreover, this coupling becomes even more important when the collision velocity increases, getting comparable or exceeding the typical electron orbiting velocities in A and B. Our results imply furthermore tha…
We observe bimodal fluorescence patterns from atoms in a fast atomic beam when the laser excitation occurs in the presence of a magnetic field and the atoms sample only a portion of the laser profile. The behavior is well explained by competition between the local intensity of the laser, which tends to generate a coherent-population-trapping (CPT) dark state in the $J=1$ to $J'=0$ system, and the strength of an applied magnetic field that can frustrate the CPT process. This work is relevant for understanding and optimizing the detection process for clocks or other coherent systems utilizing th…
The frequency stability achieved by an optical atomic clock ultimately depends on the coherence of its local oscillator. Even the best ultrastable lasers only allow interrogation times of a few seconds, at present. Here we present a universal measurement protocol that overcomes this limitation. Engineered dynamic decoupling of laser phase noise allows any optical atomic clock with high signal-to-noise ratio in a single interrogation to reconstruct the laser's phase well beyond its coherence limit. A compound clock is then formed in combination with another optical clock of any type, allowing t…
Photoelectron emission from excited states of laser-dressed atomic helium is analyzed with respect to laser intensity-dependent excitation energy shifts and angular distributions. In the two-color XUV (exteme ultra\-violet) -- IR (infrared) measurement, the XUV photon energy is scanned between \SI{20.4}{\electronvolt} and the ionization threshold at \SI{24.6}{\electronvolt}, revealing electric dipole-forbidden transitions for a temporally overlapping IR pulse ($\sim\!\SI{e12}{\watt\per \centi\meter\squared}$). The interpretation of the experimental results is supported by numerically solving t…
Electron's anomalous magnetic moment effects on laser assisted ionization of atomic hydrogen by electronic impact
本文研究了在电子反常磁矩（AMM）作用下氢原子的电子碰撞电离。本文给出了Y. Attaourti和S. Taj [Phys.Rev.A69，063411（2004）]用于检查当异常$κ$取为零时我们的计算的一致性。我们表明，即使在第一玻恩近似中，包含AMM效应的项的贡献也具有重要的贡献，因此必须将其包括在任何可靠的分析中。给出了TDCS的全解析计算。
In this study we explored the possibilities for observing the angular momentum alignment-to-orientation conversion (AOC) in the ground state of various alkali metals: K, Rb, Cs. For theoretical analysis we used a model that is based on the Optical Bloch equations for the density matrix. Our model includes the interaction of all neighboring hyperfine levels with laser radiation, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. Additionally we simulated signals where the ground- or the excited-state …
We investigated experimentally and theoretically angular momentum alignment-to-orientation conversion created by the joint interaction of laser radiation and an external magnetic field with atomic rubidium at room temperature. In particular we were interested in alignment-to-orientation conversion in atomic ground state. Experimentally the laser frequency was fixed to the hyperfine transitions of $D_1$ line of rubidium. We used a theoretical model for signal simulations that takes into account all neighboring hyperfine levels, the mixing of magnetic sublevels in an external magnetic field, the…
We study ionization dynamics of aligned diatomic molecules N$_2$ in strong elliptical laser fields experimentally and theoretically. The alignment dependence of photoelectron momentum distributions (PMDs) of N$_2$ measured in experiments is highlighted with comparing to Ar measured synchronously. Our results show that the PMDs of N$_2$ depend strongly on the alignment of the molecule, relative to the main axis of the laser ellipse. In particular, the most-probable electron-emission angle which is often used in attosecond measurement, differs remarkably when changing the molecular alignment. We…
We propose a new type of superradiant laser based on a hot atomic beam traversing an optical cavity. We show that the theoretical minimum linewidth and maximum power are competitive with the best ultracoherent clock lasers. Also, our system operates naturally in continuous wave mode, which has been elusive for superradiant lasers so far. Unlike existing ultracoherent lasers, our design is simple and rugged. This makes it a candidate for the first widely accessible ultracoherent laser, as well as the first to realize sought-after applications of ultracoherent lasers in challenging environments.
Hyperfine and Zeeman Optical Pumping and Transverse Laser Cooling of a Thermal Atomic Beam of Dysprosium Using a Single 421 nm Laser
Johannes Gutenberg-Universität Mainz（约翰内斯·古腾堡美因茨大学）；Helmholtz-Institut Mainz, GSI Helmholtzzentrum für Schwerionenforschung（亥姆霍兹美因茨研究所，GSI重离子研究中心）；Department of Physics, Indian Institute of Technology Tirupati（蒂鲁帕蒂印度理工学院物理系）；Korea National University of Education（韩国国立教育大学）；Department of Physics, University of California, Berkeley（加州大学伯克利分校物理系）
In situ accurate determination of the zero time delay between two independent ultrashort laser pulses by observing the oscillation of an atomic excited wave packet
