08 Fakultät Mathematik und Physik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/9

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Open Access
An approach to quantum physics teaching through analog experiments
(2022) Aehle, Stefan; Scheiger, Philipp; Cartarius, Holger
With quantum physics being a particularly difficult subject to teach because of its contextual distance from everyday life, the need for multiperspective teaching material arises. Quantum physics education aims at exploring these methods but often lacks physical models and haptic components. In this paper, we provide two analog models and corresponding teaching concepts that present analogies to quantum phenomena for implementation in secondary school and university classrooms: While the first model focuses on the polarization of single photons and the deduction of reasoning tools for elementary comprehension of quantum theory, the second model investigates analog Hardy experiments as an alternative to Bell’s theorem. We show how working with physical models to compare classical and quantum perspectives has proven helpful for novice learners to grasp the abstract nature of quantum experiments and discuss our findings as an addition to existing quantum physics teaching concepts.
Open Access
Aufbau einer Messapparatur zur Laserkühlung und hochauflösende Rydberg-Spektroskopie an 87 Rb-Atomen
(2006) Grabowski, Axel; Pfau, Tilman (Prof. Dr.)
Die Entwicklung der Methoden zur Laserkühlung von Atomen hat in den letzten 15 Jahren vielfältige wissenschaftliche Fortschritte erzielt. Ein sich dabei in den letzten Jahren neu entwickelndes Feld ist die Kombination der Laserkühlung mit der zustandsselektiven Anregung von Atomen in Rydberg-Zustände. Ein solches System wird als "gefrorenes Rydberg-Gas" bezeichnet. Dieser Name reflektiert die Tatsache, dass die Experimente mit diesen gekühlten Atomen auf einer Zeitskala ablaufen, auf der die thermische Bewegung zu vernachlässigen ist und nur die Wechselwirkung der Atome untereinander relevant ist. Gelingt es, solche kalten Rydberg-Atome in periodischen Potentialen zu speichern, so ergeben sich Möglichkeiten, dieses System für die Quanteninformationsverarbeitung (QIV) zu nutzen. Zur Untersuchung solcher Systeme wurde im Rahmen dieser Arbeit ein neuer experimenteller Aufbau konzipiert und realisiert. Die dazu aufgebaute Apparatur wurde charakterisiert, indem Untersuchungen zur Laserkühlung von aus einem Dispenser emittierten 87Rb-Atomen in einer magneto-optischen Falle (MOT) durchgeführt wurden. Die hierbei gekühlten Atome wurden anschließend in eine Magnetfalle in Drahtfallengeometrie transferiert und konnten dort magnetisch gespeichert werden. Zur Speicherung von ultrakalten Atomensembles in periodischen Strukturen wurden die Möglichkeiten untersucht, aus periodisch angeordneten stromtragenden Leitern ein Gitter von zwei Magnetfallentypen (Quadrupol- und Ioffe-Pritchard-Fallen) zu konstruieren. Hierzu wurden aufbauend auf einzelnen Segmenten die Möglichkeiten der Konstruktion von Gittern untersucht. Diese Gitter erlauben es, drei verschiedene Grundkonfigurationen von Fallen mit unterschiedlichen Eigenschaften aufzubauen, die theoretisch erläutert werden. Dabei wird auch eine experimentelle Realisierung solcher Gitter mit Quadrupol-Fallen vorgestellt. Hierbei wurde ein Gitter von 4 MOTs experimentell realisiert und untersucht. Im letzten Teil der Arbeit werden Experimente zur 2-Photonen Rydberg-Anregung und hochauflösenden Rydberg-Spektroskopie von 87Rb-Atomen vorgestellt. Hierbei wird zunächst das verwendete Anregungs- und Detektionsschema der Atome erläutert, gefolgt von Untersuchungen zur Stabilität und Leistungsfähigkeit des Lasersytems zur Rydberg-Anregung. Hierzu wurden hochauflösende Spektren in der Umgebung der beiden 41D-Feinstrukturzustände von 87Rb in Abhängigkeit vom elektrischen Feld aufgenommen und die feldabhängige Aufspaltung der Zustände untersucht. Zur Realisierung der erläuterten Schemata zur QIV ist es nötig, einzelne oder Ensembles von Atomen gezielt orts- und zustandsselektiv in Rydberg-Zustände anregen zu können. Erste Demonstrationsexperimente hierzu werden präsentiert. Abschließend wird über die Messung der Rabifrequenz durch Untersuchung der Autler-Townes-Aufspaltung des an das Lichtfeld gekoppelten 5S1/2->5P3/2-Übergangs berichtet.
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, Tilman
The 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.
Open Access
Coherent interaction of atoms with a beam of light confined in a light cage
(2021) Davidson-Marquis, Flavie; Gargiulo, Julian; Gómez-López, Esteban; Jang, Bumjoon; Kroh, Tim; Müller, Chris; Ziegler, Mario; Maier, Stefan A.; Kübler, Harald; Schmidt, Markus A.; Benson, Oliver
Controlling coherent interaction between optical fields and quantum systems in scalable, integrated platforms is essential for quantum technologies. Miniaturised, warm alkali-vapour cells integrated with on-chip photonic devices represent an attractive system, in particular for delay or storage of a single-photon quantum state. Hollow-core fibres or planar waveguides are widely used to confine light over long distances enhancing light-matter interaction in atomic-vapour cells. However, they suffer from inefficient filling times, enhanced dephasing for atoms near the surfaces, and limited light-matter overlap. We report here on the observation of modified electromagnetically induced transparency for a non-diffractive beam of light in an on-chip, laterally-accessible hollow-core light cage. Atomic layer deposition of an alumina nanofilm onto the light-cage structure was utilised to precisely tune the high-transmission spectral region of the light-cage mode to the operation wavelength of the atomic transition, while additionally protecting the polymer against the corrosive alkali vapour. The experiments show strong, coherent light-matter coupling over lengths substantially exceeding the Rayleigh range. Additionally, the stable non-degrading performance and extreme versatility of the light cage provide an excellent basis for a manifold of quantum-storage and quantum-nonlinear applications, highlighting it as a compelling candidate for all-on-chip, integrable, low-cost, vapour-based photon delay.
Open Access
Collapse of dipolar Bose-Einstein condensates for different trap geometries
(2010) Metz, Jonas; Pfau, Tilman (Prof. Dr.)
We experimentally investigate how the collapse dynamics of a Cr-52 Bose-Einstein condensate depends on the external harmonic trap geometry. When the collapse is initiated by reducing the s-wave scattering length below its critical value, a complex dynamics is observed, involving a d-wave symmetric explosion. We find good agreement between our experiments and simulations of the Gross-Pitaevskii equation including 3-body losses. In order to probe the phase-coherence of collapsed condensates we induce the collapse in several condensates simultaneously and let them interfere.
Open Access
Continuous wave Doppler-free spectroscopy on the 𝐀 𝟐𝚺+ ← 𝐗 𝟐𝚷𝟑/𝟐 transition in thermal nitric oxide
(2022) Kaspar, Patrick; Pfau, Tilman (Prof. Dr.)
The framework of this thesis is given by the development of a laboratory prototype for a new kind of gas sensing scheme to detect smallest quantities of nitric oxide in a large background of other gases. This thesis presents the underlying concepts of the sensing principle and some of the technical aspects developed for its investigation. In addition, the technique of Doppler-free saturated absorption spectroscopy, which is a standard technique in atomic physics, was applied to thermal nitric oxide molecules. It enabled direct resolution of the hyperfine structure and the determination of the corresponding hyperfine constants for the involved excited state. The results show the capabilities of the application of this technique to thermal molecules and in addition prove that saturation on the investigated transition is possible. This is an important result in terms of the overall goal the development of the trace gas sensor prototype.
Open Access
D-state Rydberg electrons interacting with ultracold atoms
(2014) Krupp, Alexander Thorsten; Pfau, Tilman (Prof. Dr.)
This thesis was established in the field of ultracold atoms where the interaction of highly excited D-state electrons with rubidium atoms was examined. This work is divided into two main parts: In the first part we study D-state Rydberg molecules resulting from the binding of a D-state Rydberg electron to a ground state rubidium atom. We show that we can address specific rovibrational molecular states by changing our laser detuning and thus create perfectly aligned axial or antialigned toroidal molecules, in good agreement with our theoretical calculations. Furthermore the influence of the electric field on the Rydberg molecules was investigated, creating novel states which show a different angular dependence and alignment. In the second part of this thesis we excite single D-state Rydberg electrons in a Bose-Einstein condensate. We study the lifetime of these Rydberg electrons, the change of the shape of our condensate and the atom losses in the condensate due to this process. Moreover, we observe quadrupolar shape oscillations of the whole condensate created by the consecutive excitation of Rydberg atoms and compare all results to previous S-state measurements. In the outlook we propose a wide range of further experiments including the proposal of imaging a single electron wavefunction by the imprint of its orbit into the Bose-Einstein condensate.
Open Access
Dynamic processes in Rydberg-atom-ion systems
(2024) Berngruber, Moritz; Pfau, Tilman (Prof. Dr.)
In this thesis an ion microscope is used to study ion-Rydberg interactions in a cold quantum gas of rubidium atoms in real space. This allowed the observation of charged ultralong-range Rydberg molecules consisting of an ion and a Rydberg atom. The molecule is based on a charge-induced flipping dipole bond and shows a bond length of several micrometers. Due to the versatile nature of the ion microscope, the molecules could not only be studied by means of conventional spectroscopy and mass spectrometry, but could also be directly observed in real space images. Thus, the spatial alignment, caused by the laser polarization during the photoassociation, could be detected in situ. Furthermore, the response of the molecule to an external electric field was investigated, opening up the possibility to not only associate the molecule in an aligned, but also an orientated way. Owing to the exceptionally long bond length of these molecules, dynamical processes are slowed down drastically, which provides the possibility to observe the molecular vibrational motion directly. Finally, the onset of collision dynamics between an ion and a Rydberg atom in a purely attractive potential was analyzed. At sufficiently small distances, the charge-induced Stark shift leads to a large number of avoided crossings between an atomic Rydberg state and the adjacent hydrogenic manifold. These crossings open up additional fast collision channels whose population can be described by a Landau-Zener hopping process. For a certain energy regime this results in a counter-intuitive behavior, as initially slow particles predominantly occupy steep collision channels and therefore experience a drastic speed up in the collisional process.
Open Access
Electrical detection of Rydberg interactions in nitric oxide at room temperature
(2023) Munkes, Fabian; Pfau, Tilman (Prof. Dr.)
In this work I will present measurements of Rydberg states in nitric oxide (NO) at room temperature. The detection of the Rydberg states is realized by measuring the current of free charges resulting from collisions of the excited molecules. All measurements are performed using continuous-wave (cw) lasers in a sub-Doppler configuration, which together with a stabilization setup yield a frequency error of only 2𝜋 × 2.5 MHz. The full width at half maximum (FWHM) of a typical Rydberg state is only about 2𝜋 × 130 MHz. We take a look at the necessary theory of diatomic molecules first. Afterward, a thorough walkthrough of the experimental setup is given. The heart of our setup is a custom-designed measurement cell, which features readout electronics based on a transimpedance amplifier (TIA). As such I will also give an overview on the basics of operational amplifiers (OpAmps). When all prerequisites are introduced, we will take an in-depth look on the Stark effect in Rydberg states. To our knowledge, the presented resolution is unmatched, and may enable us to give a more precise value to the g–quantum defect in NO in the future. In a final experimental section I show the collisional broadening and shift of Rydberg states of NO due to an increasing background gas density. Such measurements have a long history in alkalis, yet to our knowledge, no such measurements in NO exist. The overall experiment is performed in the context of a trace-gas sensor for NO in a medical application. This work gives suitable density and electric field ranges for such a sensor.
Open Access
Energy as a source of preservice teachers’ conceptions about radioactivity
(2024) Prokop, Axel-Thilo; Nawrodt, Ronny
Open Access
Erzeugung eines Bose-Einstein-Kondensats in einer stark anisotropen Magnetfalle
(2003) Schoser, Jürgen; Pfau, Tilman (Prof. Dr.)
Im Rahmen dieser Arbeit wurde eine Apparatur zur Erzeugung eines Bose-Einstein-Kondensats mit Rubidium-Atomen in einer stark anisotropen Fallengeometrie konzipiert und im Labor realisiert. Die Bose-Einstein-Kondensation von verdünnten atomaren Gasen wird durch verschiedene Einfang- und Kühlmethoden erreicht. Abweichend von bisherigen Experimenten wurden hier bei den einzelnen experimentellen Stufen zum Teil neue Wege begangen: Ausgehend von der Dampfphase bei Raumtemperatur wird ein intensiver Strahl kalter Atome mittels zweidimensionaler magnetooptischer Kühlung erzeugt. Dieser ermöglicht es, eine großvolumige magnetooptische Atomfalle mit einer hohen Atomzahl zu laden. Mit der hohen optischen Dichte geht zwar eine geringe Kühleffizienz einher, was jedoch durch einen speziellen Kühlschritt, eine verstimmte magnetooptische Fallen-Phase, behoben wird, um Temperaturen im Bereich der Polarisationsgradientenkühlung zu erreichen. Das so präparierte Atomensemble wird in einer Magnetfalle durch Verdampfungskühlung in ein Bose-Einstein-Kondensat überführt. Hierbei wirkt sich besonders die anisotrope Fallengeometrie auf die Effizienz des letzten Kühlschritts aus. Die hier realisierte Apparatur erlaubt es, in das quasi-eindimensionale Regime entarteter Quantengase mit einer gut detektierbaren Atomzahl vorzudringen. Ein analytisches Modell rundet die theoretische Beschreibung der zweidimensionalen magnetooptischen Kühlung ab. Darüberhinaus werden erste Experimente von Bose-Einstein-Kondensaten in optischen Gittern vorgestellt und der Einfluss von interatomarer Wechselwirkung aufgrund von s-Wellen-Streuung auf die Materiewellenbeugung an optischen Stehwellen diskutiert.
Open Access
Imaging single Rydberg electrons in a Bose-Einstein condensate
(2015) Karpiuk, Tomasz; Brewczyk, Mirosław; Rzążewski, Kazimierz; Gaj, Anita; Balewski, Jonathan B.; Krupp, Alexander T.; Schlagmüller, Michael; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman
The quantum mechanical states of electrons in atoms and molecules are distinct orbitals, which are fundamental for our understanding of atoms, molecules and solids. Electronic orbitals determine a wide range of basic atomic properties, allowing also for the explanation of many chemical processes. Here, we propose a novel technique to optically image the shape of electron orbitals of neutral atoms using electron-phonon coupling in a Bose-Einstein condensate. To validate our model we carefully analyze the impact of a single Rydberg electron onto a condensate and compare the results to experimental data. Our scheme requires only well-established experimental techniques that are readily available and allows for the direct capture of textbook-like spatial images of single electronic orbitals in a single shot experiment.
Open Access
Interacting Rydberg atoms : coherent control at Förster resonances and polar homonuclear molecules
(2012) Nipper, Johannes Maximilian; Pfau, Tilman (Prof. Dr.)
Interactions between single atoms are fundamental to physics and to control them is an ultimate goal. The exaggerated properties of Rydberg atoms offer to met the technical challenges to isolate and control single interaction channels in ultracold gases. Here, I present experiments on two subjects related to interactions of Rydberg atoms in dense ultracold clouds. One subject concerns coherence in strongly interacting ensembles of atoms, where the interaction between Rydberg atoms is induced via Stark-tuned Förster resonances. Pulsed experiments, following the idea of Ramsey experiments, are used for high resolution spectroscopy of the Förster defect and phase sensitive detection. Coherent oscillations between pair states and an interaction-induced phase shift of Rydberg atoms are measured. These experiments are accompanied by calculations of the interaction strength and by simulations using the concept of a pair state interferometer. The simulations nicely reproduce the experimental findings and support the observation that the ensemble of atoms in the presence of interactions can be described and controlled coherently. The second subject of this thesis is the measurement of a permanent dipole moment in a homonuclear diatomic molecule that arises by the interaction between a Rydberg atom and a ground state atom. Usually parity symmetry prohibits a permanent dipole moment in diatomic molecules, but here the strong asymmetry between the constituents of the ultralong-range Rydberg molecule allows breaking parity symmetry. These molecules consist of one ground state atom bound inside the Rydberg electron wavefunction of a highly excited atom. Calculations predict dipole moments on the order of 1 Debye. Experimental proof is reported on the measurement of a linear Stark effect of these molecules, in excellent agreement with the calculations.
Open Access
Ions and electrons interacting with ultracold atoms : novel approaches based on Rydberg excitations
(2018) Kleinbach, Kathrin Sophie; Pfau, Tilman (Prof. Dr.)
In this thesis, the interaction of ions and electrons with ultracold atoms was investigated at the example of Rubidium-87. Thereto, a Rydberg atom was excited in a dense ultracold cloud. Both the interaction of the ionic core of the Rydberg atom and the Rydberg electron itself with neighboring neutral atoms was studied. Two main achievements were reported: First, photo-association of hybrid Trilobite Rydberg molecules was demonstrated. This is a special type of homonuclear molecules with a large electric dipole moment, which is bound by the electron-atom interaction. Second, it was shown for the first time that the ion-atom interaction between the Rydberg ionic core and the neutral atom can be accessed experimentally. The ion-atom interaction was observed at submicrokelvin temperature, once the nearest neighbor spacing in BEC is small and the electron-atom interaction is suppressed.
Open Access
Kohärente Rydberg-Spektroskopie in einer Rubidium Mikrozelle
(2012) Kübler, Harald; Pfau, Tilman (Prof. Dr.)
Diese Arbeit befasst sich mit den Wechselwirkungen der Rydbergatome mit den Glasoberflächen. Sind diese zu stark zerfallen die Rydbergatome oder die Kohärenzen zu schnell und damit sind auch die gespeicherten Informationen verloren. Zur spektroskopischen Untersuchung der Atome wurde in dieser Arbeit eine Glaszelle entwickelt und mit Rubidium befüllt. Es wurde eine Referenzspektroskopie für die Zweiphotonenanregung in den Rydbergzustand entwickelt, aufgebaut und charakterisiert. Die Rydbergatome in der Glaszelle wurden mit einer EIT-Spektroskopie untersucht [MJA07]. Während die meisten Zustände starke Wechselwirkungen mit der Wand zeigen, wurde in dieser Arbeit ein Zustand identifiziert, der bis zu Atom-Wandabständen unter einem Mikrometer nur sehr geringe Wechselwirkungseffekte zeigt. In Kapitel 2 werden die grundlegenden Eigenschaften von Rydbergatomen vorgestellt. Ausgehend vom einfachsten Fall des Wasserstoffatoms wird auf die energetische Lage der Rydbergzustände bei Rubidium und Cäsium eingegangen und die Quantendefekttheorie vorgestellt. Abschließend wird das Verhalten in elektrischen Feldern (Stark Effekt) beschrieben. Kapitel 3 liefert die theoretischen Grundlagen für die EIT-Spektroskopie. Zuerst wird anhand eines Zweiniveausystems mittels Dichtematrixformalismus die Absorption von Licht beschrieben. Es wird auf Verbreiterungen in thermischen Atomen eingegangen und das System dann durch ein drittes Niveau und einen zweiten Laser (Coupling-Laser) erweitert. Hier spielt es für die Absorptionsspektren nun eine Rolle, welcher der beiden Laser gescannt wird. Beachtet man noch den Doppler-Effekt in thermischen Atomen, so erhält man sogar unterschiedliche Spektren für unterschiedliche Verhältnisse der Laserwellenlängen der beiden Laser. In Kapitel 4 werden die Wechselwirkungen zwischen einem Atom und einer sich in der Nähe befindenden Wand beschrieben. Kapitel 5 beschreibt die allgemeinen Teile des Aufbaus. In Kapitel 6 wird auf die Frequenzreferenz für die Zweiphotonenanregung eingegangen. Nach der Beschreibung des Aufbaus werden die Auswirkungen des Dopplereffekts beschrieben. Die Zuverlässigkeit der Referenz wird daraufhin bei der Verwendung als Stabilisierung experimentell überprüft. Bei den folgenden Simulationen für die Scanreferenz werden zwei Fälle für verschiedene Wellenlängenverhältnisse der beteiligten Laser unterschieden. Eine Kombination entspricht einem möglichen Anregungsweg in Rubidium, die andere mit umgekehrtem Wellenlängenverhältnis einem in Cäsium. Anschließend wird die Übereinstimmung mit einem gemessenen Referenzspektrum gezeigt. Kapitel 7 beinhaltet den Aufbau für die Mikrozellen und die daran durchgeführten Messungen. Neben einer Abschätzung der zu erwartenden Linienbreiten ohne die Wandwechselwirkung werden Vergleichsmessungen zwischen verschiedenen Rydbergzuständen gezeigt. Es wird versucht, diese Spektren durch elektrische Felder und Polaritonen (Anregungen in den Wänden) zu erklären. In Kapitel 8 werden die Beobachtungen nochmals zusammengefasst, interpretiert und ein Ausblick auf weitere mögliche Schritte gegeben.
Open Access
Large bandwidth excitation of Rydberg atoms in thermal vapor : fast dynamics and strong interaction effects
(2016) Urvoy, Alban; Pfau, Tilman (Prof. Dr.)
Open Access
Laser cooling of a magnetically guided ultra cold atom beam
(2014) Aghajani-Talesh, Anoush; Pfau, Tilman (Prof. Dr.)
This thesis examines two complimentary methods for the laser cooling of a magnetically guided ultra-cold atom beam. If combined, these methods could serve as a starting point for high-through put and possibly even continuous production of Bose-Einstein condensates. First, a mechanism is outlined to harvest ultra cold atoms from a magnetically guided atom beam into an optical dipole trap. A continuous loading scheme is described that dissipates the directed kinetic energy of a captured atom via deceleration by a magnetic potential barrier followed by optical pumping to the energetically lowest Zeeman sublevel. The application of this scheme to the transfer of ultra cold chromium atoms from a magnetically guided atom beam into a deep optical dipole trap is investigated via numerical simulations of the loading process. Based on the results of the theoretical studies the feasibility and the efficiency of our loading scheme, including the realisation of a suitable magnetic field configuration, are analysed. Second, experiments were conducted on the transverse laser cooling of a magnetically guided beam of ultra cold chromium atoms. Radial compression by a tapering of the guide is employed to adiabatically heat the beam. Inside the tapered section heat is extracted from the atom beam by a two-dimensional optical molasses perpendicular to it, resulting in a significant increase of atomic phase space density. A magnetic offset field is applied to prevent optical pumping to untrapped states. Our results demonstrate that by a suitable choice of the magnetic offset field, the cooling beam intensity and detuning, atom losses and longitudinal heating can be avoided. Final temperatures below 65 µK have been achieved, corresponding to an increase of phase space density in the guided beam by more than a factor of 30.
Open Access
Laser cooling of barium monofluoride
(2024) Rockenhäuser, Marian; Pfau, Tilman (Prof. Dr.)
In this work, the first implementation of direct laser cooling of barium monofluoride (BaF) molecules using sub-Doppler forces is presented. This species is a promising candidate for parity violation measurements, the search for the electron’s permanent electric dipole moment and ultracold chemistry. However, due to its large mass, comparatively narrow linewidth and potential branching losses through an intermediate electronic state, this molecular species is notoriously difficult to cool. To achieve laser cooling, first, spectroscopic measurements of the relevant optical transitions were performed. This allowed for an improvement of the molecular constants by one order of magnitude. Next, Doppler-free spectroscopy was conducted on the cooling transition, which revealed a resolved hyperfine splitting in the excited state. Previous molecular laser cooling experiments employed sinusoidal sideband modulation to address such hyperfine structure states. Here, serrodyne modulation was used to create optimized optical spectra, resulting in significantly improved laser cooling. Finally, a Raman cycling scheme was implemented to achieve background-free imaging of the resulting cold molecular beam. In conclusion, an intense and transversally cold molecular beam of 138BaF was prepared, which paves the way for precision tests of fundamental symmetries using BaF.
Open Access
Laser cooling of barium monofluoride molecules using synthesized optical spectra
(2024) Rockenhäuser, Marian; Kogel, Felix; Garg, Tatsam; Morales-Ramírez, Sebastián A.; Langen, Tim
Open Access
Long-lived circular Rydberg qubits of alkaline-earth atoms in optical tweezers
(2024) Hölzl, Christian; Götzelmann, Aaron; Pultinevicius, Einius; Wirth, Moritz; Meinert, Florian