Exitation of atomic levels due to interaction with electromagnetic waves has been the subject of numerous works, both experimental and theoretical. This topic became of interest in accelerator physics in relation to high efficiency charge exchange injection into rings for high beam power applications. Taking equations of resonant atom-wave interaction equations as a basis, this paper shows that there exist some interesting phenomena which lead to the existence of trapped electomagnetic waves (photon traps) in a medium that consists of atoms with transition frequencies in proximity to the wave frequency. These traps may exist in random and periodic lattices, and may have very low loss rate. The atomic medium can serve as an excellent wavegiude or tool to form and transmit electromagnetic waves for applications to accelerators and to electromagnetic devices in general, where high pressure gas use is acceptable. In addition, such traps in gases may accumulate substantial energy for a long period of time, leading to the possibility of creating objects similar (or equivalent) to ball lightning.
Exitation of atomic levels due to interaction with electromagnetic waves has been the subject of numerous works, both experimental and theoretical. This topic became of interest in accelerator physics in relation to high efficiency charge exchange injection into rings for high beam power applications. Taking equations of resonant atom-wave interaction equations as a basis, this paper shows that there exist some interesting phenomena which lead to the existence of trapped electomagnetic waves (photon traps) in a medium that consists of atoms with transition frequencies in proximity to the wave frequency. These traps may exist in random and periodic lattices, and may have very low loss rate. The atomic medium can serve as an excellent wavegiude or tool to form and transmit electromagnetic waves for applications to accelerators and to electromagnetic devices in general, where high pressure gas use is acceptable. In addition, such traps in gases may accumulate substantial energy for a long period of time, leading to the possibility of creating objects similar (or equivalent) to ball lightning.
The excitation of atomic levels due to interaction with electromagnetic waves became of interest in accelerator physics in relation to high efficiency charge exchange injection into rings for high beam power applications. Usually, the beam density is so small that its influence on the wave is completely neglected. Here we consider the case of dense beams - the beam dimensions are large as compared to light reflection length. This paper shows that the waves can be trapped in the medium under these conditions. Moreover, the atoms with induced dipole moments start to interact strongly with each other, leading to possibility to create some atomic patterns when the medium is relatively cold.
This paper proposes a theoretical model in which the coupling between the electron and proton inside the hydrogen atom generates a confined electromagnetic field characterized by stable resonant modes. The model assumes that this field propagates at the speed of light and forms standing-wave structures confined within the atomic system. Unlike conventional interpretations that treat the electron purely as a probabilistic quantum object, the present approach considers the possibility that quantized atomic behavior emerges from resonant electromagnetic confinement.The study introduces a resonance-based framework capable of linking atomic stability to discrete electromagnetic frequencies associated with the hydrogen atom. Specific resonant frequencies and wavelength relations are derived and compared with known spectral transitions. The model further predicts the existence of internally confined electromagnetic patterns that may explain energy quantization from a wave-resonance perspective.In addition, the proposed framework offers potential reinterpretations of atomic transitions, field localization, and energy exchange mechanisms inside simple atomic systems. The work is presented as a preliminary theoretical foundation intended for further mathematical development, analytical derivation, and experimental examination.
We duscuss a resonant microwave trap for neutral atoms. Because of the long spontaneous radiation time this trap is remarkably different from the optical trap. It also has advantages over static magnetic traps that trap the excited spin state of the lowest electronic level, in that atoms predominantly in the spin ground state can be trapped. We analyze the relaxation-ejection lifetime of atoms in such a trap using the formalism of dressed atomic states. Results are appliedi to atomic hydrogen and the possibility of Bose-Einstein condensation is considered.
This dissertation presents a theoretical analysis of methods to manipulate and control the momentum state of coherent matter waves. Of particular interest is the coherent acceleration of a quantum-degenerate atomic system, which, as a direct consequence of the form of the de Broglie wavelength, results in tunable source of matter waves. Such sources are of considerable importance for a number of potential applications in the field of atom optics, including the development of highly sensitive gyroscopes, accelerometers, gravity gradiometers or atom lithography and holography, as well as for potential uses in integrated atom optics. Our basic setup consists of a Bose-Einstein condensate in a moving optical lattice created by a pair of frequency-chirped counterpropagating laser beams acting as a "conveyor belt'' for ultracold atoms. Whereas the acceleration of ultracold but non-condensed atoms in such a lattice was demonstrated earlier, we extend this scheme to the case of Bose-Einstein condensates. As a first step, we investigate the acceleration efficiency for various acceleration rates and nonlinear interaction strengths. We find parameter regimes where efficient acceleration is possible, i.e. all atoms are accelerated to the same velocity and the initially sharp momentum distribution and thus its monochromaticity is preserved. However, in general we identify switch-on effects of the lattice, dynamical loss and nonlinear effects to be responsible for deterioration of the monochromaticity of the condensate: On the one hand, switch-on effects and dynamical loss induce a coupling of the initially populated momentum mode to other modes, thereby distributing the momentum over several modes. On the other hand, the nonlinear release of mean field energy during the acceleration process causes the mode profile itself to broaden, also leading to a contamination of the initial monochromaticity. As a second step, we discuss ways to improve this scheme by removing the restriction of constant accelerations. We employ genetic algorithms to optimize the time-dependent motion of the lattice. We show that with such flexibility, it is possible to achieve a fast and highly efficient coherent acceleration of condensates, even when mean-field effects cannot be neglected. The same scheme also enables the creation of arbitrary coherent superposition states in momentum space. The technique is thus suitable for building highly efficient momentum state beam splitters. In addition to simply accelerating condensates, it is desirable for many potential applications to transport atomic wave packets without dispersion over large distances. This can be achieved by launching bright atomic solitons, where the effects of the nonlinearity counterbalance the dispersion. Placing a Bose-Einstein condensate with repulsive interactions in a lattice, one can create a negative effective mass. Under these circumstances bright and stable soliton solutions exist, so-called gap solitons. After a careful analysis of the soliton properties, we use the tools we developed for condensate acceleration and demonstrate two feasible schemes to excite the solitons. Experimental data released after publication of our results demonstrating the acceleration of Bose-Einstein condensates in moving lattices and the very recent observation of atomic gap solitons indicates that our theoretical analysis was timely and indeed experimentally feasible. As an outlook, we briefly comment on a new direction in the field of atom optics that holds promise for future applications: the use of quantum degenerate Fermi gases. In atomic as well as in optical physics one often encounters situations where there exists a coupling between several modes of a system. Here, we illustrate the "toy model'' of a fermionic coupler where transitions between two internal states are induced by Raman coupling. Due to Fermi statistics and interatomic interactions, this is a simple example of a nonlinear multimode coupler. Investigation of this system consisting of only a few fermions already clearly illustrates the basic differences between bosonic and fermionic dynamics and sheds light on the role of two-body collisions. Understanding the basic mechanisms of this system is a first step towards more sophisticated coherent control of fermionic systems.
Electromagnetic trapping of neutral atoms is a new branch of applied physics that has potential for use in very many areas, including metrology and high-resolution precision spectroscopy. It has the possibility of leading toward the spectroscopic ideal of an isolated atom at rest, available for interaction with electromagnetic field probes. We present an introduction to trapping in both dc magnetic fields and optical fields (laser beams). The basic ideas and fundamental limitations are discussed and the first successful experiments are reviewed.
In this habilitation-thesis a collection of 14 experiments is presented. In these experiments we have developed and used novel techniques to control ultracold gases on the quantum level. In brief, Bose-Einstein condensates (BEC) and degenerate Fermi gases of laser-cooled alkali atoms are subjected to specially designed optical and magnetic fields. The fields influence in a coherent way the behavior, properties and dynamics of the gases. On this basis we developed tools to prepare, coherently manipulate, and analyze pre-defined quantum states. With this high level of control, it was possible to investigate interesting physics phenomena, and we were able to achieve several breakthroughs in the field of ultracold atoms. Highlights of our experimental results include the demonstration of phase engineering of a BEC wavefunction where we created solitons in a BEC and studied their propagation. In another experiment we constructed a spatially resolved matter wave interferometer with which we mapped out the phase distribution on a condensate. Illuminating the BEC with a periodic pattern, i.e. an optical lattice, allowed us to study solid states physics phenomena. In a second set of experiments we demonstrated optically tuning of the interaction between atoms with optical Feshbach resonances. Employing either magnetically tunable Feshbach resonances or laser radiation, we were able to produce ground state molecules in well defined quantum states. This led to the production of the first molecular BEC. By tuning the coupling of atom pairs in a Fermi gas of atoms, we could for the first time investigate the so-called BEC-BCS crossover which describes the continuous change from a BEC superfluid to a Bardeen-Cooper Schrieffer (BCS) superfluid. Due to the excellent control on the quantum level, the developed cold atom techniques open up intriguing prospects for future applications and experiments. They represent a general tool box to investigate fundamental physical phenomena in a pure and undisturbed environment. In the future, cold atoms might serve as a testing ground for fundamental theories or as quantum simulators for complex systems.