We report on the formation of translationally cold NaCs molecules starting from a laser-cooled atomic vapor of Na and Cs atoms. Colliding atoms are transferred into bound molecular states in a two-step photoactivated process in which the atoms are first photoassociated by trap photons into an excited state molecular complex and then allowed to decay into a bound molecular ground state. Time-of-flight measurements show a translational temperature T = 260± 130 K that reflects the measured temperature of the initial atomic gas.

Non-pharmaceutical interventions (NPIs) are important to mitigate the spread of infectious diseases as long as no vaccination or outstanding medical treatments are available. We assess the effectiveness of the sets of non-pharmaceutical interventions that were in place during the course of the Coronavirus disease 2019 (Covid-19) pandemic in Germany. Our results are based on hybrid models, combining SIR-type models on local scales with spatial resolution. In order to account for the age-dependence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we include realistic prepandemic and recently recorded contact patterns between age groups. The implementation of non-pharmaceutical interventions will occur on changed contact patterns, improved isolation, or reduced infectiousness when, e.g., wearing masks. In order to account for spatial heterogeneity, we use a graph approach and we include high-quality information on commuting activities combined with traveling information from social networks. The remaining uncertainty will be accounted for by a large number of randomized simulation runs. Based on the derived factors for the effectiveness of different non-pharmaceutical interventions over the past months, we provide different forecast scenarios for the upcoming time.

We describe the realization of a DC electric field trap for ultracold polar molecules, the Thin WIre electroStatic Trap (TWIST). The thin wires that form the electrodes of the TWIST allow us to superimpose the trap onto a magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules in their electronic ground state are created in the MOT via photoassociation, achieving a continuous accumulation in the TWIST of molecules in low-field seeking states. Initial measurements show that the TWIST trap lifetime is limited only by the background pressure in the chamber.PACS numbers: 33.80. Ps, 32.80Pj, 33.15Kr, 34.50.Gb Recently, there has been a growing interest in the study of ultracold molecules. While the rich internal structure of molecules poses new challenges in terms of the methods used for cooling and trapping them, the possible applications of cold molecules are remarkable. This is especially true for strongly polar molecules [1,2,3,4,5,6]. Examples include experiments in superchemistry, tests of fundamental symmetries such as the search for a permanent dipole moment of the electron, quantum information processing and the realization of dipolar quantum gases such as polar Bose-Einstein Condensates. For most of these applications, both rovibrational state selectivity and robust trapping schemes are essential. Multiple approaches have been pursued to achieve these two goals simultaneously. For example, buffer gas cooling joined with magnetic trapping [7], Stark deceleration [8] and velocity selection [9] joined with electrostatic/electrodynamic (DC/AC) trapping [10,11,12] and photoassociation [13,14,15,16,17,18] joined with magnetic trapping [19] have all been realized and have attracted substantial interest. Each technique has its advantages as well as limitations, often involving trade-offs between stateselectivity and trapped molecule number, density and temperature.Photoassociation offers the unique starting point in terms of the formation of cold polar molecules because it transfers the initial ultracold temperature of the constituent atoms onto the molecules. This easily results in molecular kinetic temperatures of a few 100 µK and with only a little extra effort, much lower temperatures can be achieved by cooling the atoms beyond the Doppler limit with well established methods [20]. In terms of stateselectivity and control, pump-and-dump and STIRAP (STImulated Raman Adiabatic Passage) based methods have both been demonstrated recently [21,22]. However, to accumulate a sample of ultracold molecules via photoassociation a robust trap is needed that is compatible with the photoassociation process.The preferred starting point for photoassociation of cold polar molecules are bialkali atomic mixtures, cooled and trapped in a MOT. Cold dense samples of alkali atoms are readily created and the resulting polar molecules display strong dipole moments (typically several Debye) in the deeply bound levels of their X 1 Σ state [23]. It is important to note, however, that magnetic trapping of molecules ...

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The formation of electronic ground-state NaCs molecules from ultracold atoms by photoassociation is explored both experimentally and theoretically. We observe saturation of the photoassociation process as well as complete ionization of the molecular sample by resonant two-photon absorption. Measured absolute molecule formation rates are compared to theoretical calculations and shown to be in good agreement.

Non-pharmaceutical interventions (NPIs) are important to mitigate the spread of infectious diseases as long as no vaccination or outstanding medical treatments are available. We assess the effectiveness of the sets of non-pharmaceutical interventions that were in place during the course of the Coron-avirus disease 2019 (Covid-19) pandemic in Germany. Our results are based on hybrid models, combining SIR-type models on local scales with spatial resolution. In order to account for the age-dependence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we include realistic pre-pandemic and recently recorded contact patterns between age groups. The implementation of non-pharmaceutical interventions will occur on changed contact patterns, improved isolation, or reduced infectiousness when, e.g., wearing masks. In order to account for spatial heterogeneity, we use a graph approach and we include high-quality information on commuting activities combined with traveling information from social networks. The remaining uncertainty will be accounted for by a large number of randomized simulation runs. Based on the derived factors for the effectiveness of different non-pharmaceutical interventions over the past months, we provide different forecast scenarios for the upcoming time.Mathematics Subject Classification (2010) 00A72 · 65L05 · 68U20

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