Universität Stuttgart
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Item Open Access Cavity QED based on room temperature atoms interacting with a photonic crystal cavity : a feasibility study(2020) Alaeian, Hadiseh; Ritter, Ralf; Basic, Muamera; Löw, Robert; Pfau, TilmanThe paradigm of cavity QED is a two-level emitter interacting with a high-quality factor single-mode optical resonator. The hybridization of the emitter and photon wave functions mandates large vacuum Rabi frequencies and long coherence times; features that so far have been successfully realized with trapped cold atoms and ions, and localized solid-state quantum emitters such as superconducting circuits, quantum dots, and color centers Reiserer and Rempe (Rev Modern Phys 87:1379, 2015), Faraon et al. (Phys Rev 81:033838, 2010). Thermal atoms, on the other hand, provide us with a dense emitter ensemble and in comparison to the cold systems are more compatible with integration, hence enabling large-scale quantum systems. However, their thermal motion and large transit-time broadening is a major bottleneck that has to be circumvented. A promising remedy could benefit from the highly controllable and tunable electromagnetic fields of a nano-photonic cavity with strong local electric-field enhancements. Utilizing this feature, here we investigate the interaction between fast moving thermal atoms and a nano-beam photonic crystal cavity (PCC) with large quality factor and small mode volume. Through fully quantum mechanical calculations, including Casimir-Polder potential (i.e. the effect of the surface on radiation properties of an atom), we show, when designed properly, the achievable coupling between the flying atom and the cavity photon would be strong enough to lead to quantum interference effects in spite of short interaction times. In addition, the time-resolved detection of different trajectories can be used to identify single and multiple atom counts. This probabilistic approach will find applications in cavity QED studies in dense atomic media and paves the way towards realizing large-scale, room-temperature macroscopic quantum systems aimed at out of the lab quantum devices.Item Open Access Atomic beam splitters based on light(1993) Adams, Charles S.; Pfau, Tilman; Mlynek, JürgenIn this paper we review techniques to coherently split an atomic beam using the dipole force. We discuss the interaction of atoms with normal standing wave light field in the context of atomic beam splitters. The case where the atom enters the standing wave at a small angle such that Bragg diffraction and velocity selective resonances are observed is also considered. An alternative approach to realize a coherent beam splitter based on the optical Stem-Gerlach effect is discussed. Finally we consider the interaction of atoms with a magneto-optical potential formed by a polarization gradient light field and a static magnetic field. We show that the Stem-Gerlach effect and the magneto-optical potential produce a more effective beam splitting into states with high tranverse momentum than diffraction from a normal standing wave.Item Open Access Optical elements for atoms : a beamsplitter and a mirror(1993) Sigel, Martin; Pfau, Tilman; Adams, Charles S.; Kurtsiefer, Christian; Seifert, Werner; Heine, Claus; Mlynek, Jürgen; Kaiser, Robin; Aspect, AlainIn the first part of this article we attempt to provide a very brief introduction to atom optics. In the second and third part we report on recent experiments in our group on two specific atom-optical elements that may be useful in atom interferometers and atom cavities: the demonstration of a new beam splitter based on the diffraction of atomic matter waves from a "magneto-optical grating" and the investigation of a mirror based on the reflection of atoms from an evanescent light field.Item Open Access Diffraction of atoms from optical potentials(1994) Pfau, Tilman; Schnetz, Andreas; Adams, Charles S.; Kurtsiefer, Christian; Sigel, Martin; Mlynek, JürgenIn the first part of this article we attempt to provide a very brief introduction to atom optics. In the second part we report on a recent experiment in our group on an atom-optical element that may be useful in atom interferometers and atom cavities: the demonstration of a new beam splitter based on the diffraction of atomic matter waves from a "magneto-optical grating".Item Open Access Imaging and focusing of an atomic beam with a large period standing light wave(1992) Sleator, Tycho; Pfau, Tilman; Balykin, Victor; Mlynek, JürgenA novel atomic lens scheme is reported. A cylindrical lens potential was created by a large period ( 45 μm) standing light wave perpendicular to a beam of metastable He atoms. The lens aperture (25 μm) was centered in one antinode of the standing wave; the laser frequency was nearly resonant with the atomic transition 2 3 S 1 – 2 3 P 2 (lambda=1.083 μm) and the interaction time was significantly shorter than the spontaneous lifetime (100 ns) of the excited state. The thickness of the lens was given by the laser beam waist (40μm) in the direction of the atomic beam. Preliminary results are presented, where an atomic beam is focused down to a spot size of 4μm. Also, a microfabricated grating with a period of 8m was imaged. We discuss the principle limitations of the spatial resolution of the lens given by spherical and chromatic aberrations as well as by diffraction. The fact that this lens is very thin offers new perspectives for deep focusing into the nm range.Item Open Access Neue Entwicklungen in der Atomoptik(1994) Pfau, Tilman; Mlynek, JürgenKlassische refraktive Optik beschäftigt sich mit der Beeinflussung von Lichtstrahlen mit Hilfe von dielektrischer Materie. In der refraktiven Atomoptik werden "dielektrische" Atomstrahlen mit Hilfe von Lichtfeldern fokussiert, reflektiert und kohärent geteilt. Mit Hilfe dieser atomoptischen Elemente lassen sich optische Systeme realisieren, die vielfältige Anwendung finden können, beispielsweise als hochempfindliche interferometrische Präzisionsmeßgeräte, in der Atomlithographie oder in Grundlagenexperimenten der Quantenmechanik.Item Open Access Ultraviolet photodetectors and readout based on a‐IGZO semiconductor technology(2023) Schellander, Yannick; Winter, Marius; Schamber, Maurice; Munkes, Fabian; Schalberger, Patrick; Kuebler, Harald; Pfau, Tilman; Fruehauf, NorbertIn this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time tRES, and a good noise equivalent power value NEP.Item Open Access Interactions of atoms with a magneto-optical potential(1993) Adams, Charles S.; Pfau, Tilman; Kurtsiefer, Christian; Mlynek, JürgenA theoretical study of the coherent interaction of multilevel atoms with a magneto-optical potential is presented. The potential is formed by counterpropagating linearly polarized laser beams whose polarization vectors intersect at an angle cphi and a static magnetic field applied parallel to the laser propagation direction. For a particular ratio of the light and magnetic field amplitudes, the light shift at positions of purely circularly polarized light is equal to the Zeeman splitting. In this case, for a three-level atom, one of the eigenvalues has a triangular spatial form. The diffraction of atoms from this triangular phase grating is an efficient beam splitter. The splitting is symmetric for cphi=90° and asymmetric for cphi<90°. In addition we show that at well-defined positions in the light field, the atom undergoes nonadiabatic transitions and thus by using state-selective detection, one could observe an interference pattern produced by an array of double slits.Item Open Access Atom interferometry with mechanical structures(1992) Sleator, Tycho; Carnal, Olivier; Pfau, Tilman; Faulstich, Andreas; Takuma, Hiroshi; Mlynek, JürgenWe present results on an interferometer for atoms based on Young's double-slit experiment. We also discuss proposed experiments in which the effect of spontaneous emission on the visibility of the atomic fringe pattern, as well as the effect of coherent atom-light interactions on the phase of the atomic wavefunction could be measured.Item Open Access Magneto-optical beam splitter for atoms(1993) Pfau, Tilman; Kurtsiefer, Christian; Adams, Charles S.; Sigel, Martin; Mlynek, JürgenWe report an experimental demonstration of diffraction of He* atoms from a magneto-optical grating. The grating was produced by the interaction of three-level atoms with a light field of spatially varying polarization and a magnetic field. For a light shift matched to the Zeeman shift, a two-peaked diffraction pattern was observed, corresponding to a momentum splitting of 42ħk. The effect of changing the polarizations of the light field was investigated. The diffraction from the magneto-optical grating is compared directly with the diffraction of two-level atoms from a standing light wave and it is shown, that the magneto-optical interaction leads to more efficient coupling into high order momentum states.