8E-17 fractional laser frequency instability with a long room-temperature cavity

We present a laser system based on a 48 cm long optical glass resonator. The large size requires a sophisticated thermal control and optimized mounting design. A self balancing mounting was essential to reliably reach sensitivities to acceleration of below $\Delta \nu / \nu$ < 2E-10 /g in all directions. Furthermore, fiber noise cancellations from a common reference point near the laser diode to the cavity mirror and to additional user points (Sr clock and frequency comb) are implemented. Through comparison to other cavity-stabilized lasers and to a strontium lattice clock an instability of below 1E-16 at averaging times from 1 s to 1000 s is revealed

Characterization of a 450-km Baseline GPS Carrier-Phase Link using an Optical Fiber Link

A GPS carrier-phase frequency transfer link along a baseline of 450 km has been established and is characterized by comparing it to a phase-stabilized optical fiber link of 920 km length, established between the two endpoints, the Max-Planck-Institut f\"ur Quantenoptik in Garching and the Physikalisch-Technische Bundesanstalt in Braunschweig. The characterization is accomplished by comparing two active hydrogen masers operated at both institutes. The masers serve as local oscillators and cancel out when the double differences are calculated, such that they do not constitute a limitation for the GPS link characterization. We achieve a frequency instability of 3 x 10^(-13) in 30 s and 5 x 10^(-16) for long averaging times. Frequency comparison results obtained via both links show no deviation larger than the statistical uncertainty of 6 x 10^(-16). These results can be interpreted as a successful cross-check of the measurement uncertainty of a truly remote end fiber link.Comment: 14 pages, 6 figure

Long range transport of ultra cold atoms in a far-detuned 1D optical lattice

We present a novel method to transport ultra cold atoms in a focused optical lattice over macroscopic distances of many Rayleigh ranges. With this method ultra cold atoms were transported over 5 cm in 250 ms without significant atom loss or heating. By translating the interference pattern together with the beam geometry the trap parameters are maintained over the full transport range. Thus, the presented method is well suited for tightly focused optical lattices that have sufficient trap depth only close to the focus. Tight focusing is usually required for far-detuned optical traps or traps that require high laser intensity for other reasons. The transport time is short and thus compatible with the operation of an optical lattice clock in which atoms are probed in a well designed environment spatially separated from the preparation and detection region.Comment: 14 pages, 6 figure

Efeito de um imunomodulador na qualidade do colostro e na incidência de doenças no pós-parto de vacas leiteiras

Dissertação de Mestrado Integrado em Medicina VeterináriaEste estudo analisou a eficácia do pegbovigrastim (ImrestorTM) na incidência de doenças no pós-parto de vacas leiteiras e o seu efeito na qualidade do colostro. Às vacas do grupo experimental foi administrado pegbovigrastim e às vacas do grupo controlo soro fisiológico. Não se observaram diferenças significativas no número de neutrófilos e macrófagos nos esfregaços de colostro. Contudo, os seus valores máximos foram superiores no colostro de vacas do grupo ImrestorTM. Verificou-se que no colostro não centrifugado das vacas tratadas com ImrestorTM o número de linfócitos foi tendencialmente superior (p=0,08). O colostro de vacas que receberam as duas doses de ImrestorTM teve uma média de 300 mil células/ml superior ao colostro do grupo controlo. A incidência de mastites, metrites e RP foi inferior no grupo experimental, comparativamente ao grupo controlo, contudo esta redução não foi estatisticamente significativa. O valor Brix foi semelhante entre os dois grupos em estudo. Não se observaram diferenças significativas entre os dois grupos na produção leiteira acumulada no primeiro mês após o parto. A percentagem de vacas com hipercetonémia foi 5,3% no grupo experimental e 8,2% no grupo controlo. É de todo o interesse que futuramente se desenvolvam mais estudos de modo a obter conclusões mais consolidadas.ABSTRACT - EFFECT OF AN IMMUNOMODULATOR IN THE QUALITY OF COLOSTRUM AND THE INCIDENCE OF DISEASES IN THE POSTPARTUM OF DAIRY COWS - This study examined the efficacy of pegbovigrastim (ImrestorTM) on the incidence of postpartum diseases in dairy cows and its effect on the quality of colostrum. Cows in the experimental group received pegbovigrastim and cows in the control group saline solution. No significant differences were observed in the number of neutrophils and macrophages in the colostrum. However, its maximum values were higher in colostrum of the ImrestorTM group. It was found that in the non-centrifuged colostrum of cows treated with ImrestorTM the number of lymphocytes was tendentially higher (p=0,08). The colostrum of cows that received the two doses of ImrestorTM was an average of 300,000 cells/ml higher than colostrum in the control group. The incidence of mastitis, metritis and RP was lower in the experimental group, compared to the control group, but this reduction was not statistically significant. The Brix value was similar between the two groups under study. There were no significant differences between the two groups in milk production accumulated in the first month after calving. The percentage of cows with hyperketonemia was 5.3% in the experimental group and 8.2% in the control group. It is of great interest that more studies are carried out in the future in order to obtain more consolidated conclusions.Fonte de Leite Exploração Agrícola e Pecuária, S.A.N/

Geodesy and metrology with a transportable optical clock

partially_open24openGrotti, Jacopo; Koller, Silvio; Vogt, Stefan; Häfner, Sebastian; Sterr, Uwe; Lisdat, Christian; Denker, Heiner; Voigt, Christian; Timmen, Ludger; Rolland, Antoine; Baynes, Fred N.; Margolis, Helen S.; Zampaolo, Michel; Thoumany, Pierre; Pizzocaro, Marco; Rauf, Benjamin; Bregolin, Filippo; Tampellini, Anna; Barbieri, Piero; Zucco, Massimo; Costanzo, Giovanni A.; Clivati, Cecilia; Levi, Filippo; Calonico, DavideGrotti, Jacopo; Koller, Silvio; Vogt, Stefan; Häfner, Sebastian; Sterr, Uwe; Lisdat, Christian; Denker, Heiner; Voigt, Christian; Timmen, Ludger; Rolland, Antoine; Baynes, Fred N.; Margolis, Helen S.; Zampaolo, Michel; Thoumany, Pierre; Pizzocaro, Marco; Rauf, Benjamin; Bregolin, Filippo; Tampellini, Anna; Barbieri, Piero; Zucco, Massimo; Costanzo, Giovanni A.; Clivati, Cecilia; Levi, Filippo; Calonico, David

Neuartige Konzepte zur Detektion und Kontrolle der Carrier-Envelope Phasendrift ultrakurzer Laserimpulse

Diese Arbeit beschäftigt sich mit der Carrier-Envelope Phasendrift modengekoppelter Laser sowie Maßnahmen zu deren aktiver und passiver Stabilisierung. Das restliche Phasenrauschen wird in verschiedenen Messaufbauten im Hinblick auf physikalische Ursachen und mögliche Optimierungen untersucht. Dazu werden einführend verschiedene Interferometeranordnungen zur Messung der CEP Drift von Ti:Saphir Oszillatoren systematisch auf ihr Eigenrauschen hin untersucht. In einem Vergleichsexperiment wird die Überlegenheit kompakter Interferometeraufbauten demonstriert. Zusätzlich wird eine einfache Anordnung vorgestellt, welche die Bestimmung der Phase eines spektralen Interferenzmusters. Das analoge Verfahren wird zur Einzelschussanalyse der CEP Drift von Verstärkerimpulsen verwendet. Hiermit werden erstmals schnelle Rauschbeiträge aufgedeckt. Ergänzend wird ein Konzept zur orthogonalen Kontrolle der CEP Drift mithilfe einer speziellen Kompensatoreinheit diskutiert. Der Kompensator besteht aus zwei Keilprismen, hergestellt aus unterschiedlichen optischen Materialien, die als Einheit verschoben werden. Durch geeignete Wahl der Materialien werden Effekte auf die Gruppenlaufzeit oder deren Dispersion gleichzeitig eliminiert. Darüber hinaus wird ebenfalls erstmalig ein lineares Messverfahren demonstriert, das die CEP Drift auch für ps-Oszillatoren erschließt. Zur linearen Detektion wird die spektrale Interferenz aufeinander folgender Impulse eines Impulszuges aufgelöst, die mit einem Ringresonator überlagert werden. Abschließend wird ein neues Verfahren präsentiert, das einen Impulszug generiert, dessen Einzelimpulse eine identische Feldstruktur aufweisen. Dazu das Messsignal direkt an ein externes Rückstellelement übergeben ohne eine zusätzliche Regelschleife zu benötigen. Auf diese Weise können Bandbreitenprobleme der Regelschleife vermieden werden. Da Rückstellelement und Laser voneinander getrennt sind, bleibt der Laser in seinem Betrieb ungestört.This work discusses the carrier-envelope phase drift of mode-locked lasers as well as techniques for its active and passive stabilization. In order to reveal the physical origin of the drift, the investigations focus on the analysis of residual phase noise. From the analysis, potential improvements are developed. For this purpose, in a first experimental approach, different interferometer configurations for CEP drift detection of Ti:sapphire oscillators are compared. Comparative studies clearly reveal the superiority of compact interferometer set-ups in terms of noise. In a second series of experiments, a simple assembly is introduced for the direct extraction of the phase from spectral interference patterns. The analog method is demonstrated with single-shot measurements and utilized for stabilization of the CEP drift of an amplifier system, thereby enabling monitoring of additional fast noise contributions for the first time. Moreover, a concept for orthogonal control of the CEP drift by a specially designed compensator assembly is discussed. This assembly consists of two thin wedge prisms made from different optical materials. By choosing an appropriate material group delay and its dispersion are eliminated synchronously. Furthermore, a linear method is presented that provides access to the CEP drift of ps-oscillators for the first time. The newly introduced much more general linear approach relies on resolving the spectral interference of subsequent pulses from a pulse train, which are superimposed utilizing a ring resonator. Finally, a technique is demonstrated that generates a pulse train consisting of single pulses with identical field structure. Particularly, the heterodyne signal is directly fed forward to the external feedback element, replacing the classical servo loop. Therefore, servo bandwidth limitations are eliminated. Since feedback element and laser oscillator are decoupled, the laser performance is not corrupted by side effects from the feedback