Auf mehrartigen Wiesen die Futterauswahl von weidenden Milchkühen bestimmen. (Determining the choice of feed of grazing dairy cows on multi-species pastures)

Ziel der Studie war das Vorgehen zur Schätzung der Futterauswahl von weidenden Milchkühen zu untersuchen. Zusätzlich wurde nach Unterschieden bezüglich der Futterauswahl zwischen schweizerischen (HCH) und neuseeländischen Holsteinkühen (HNZ) gesucht. Die 16 Kuhpaare wurden gleichmässig auf zwei Messwochen aufgeteilt und weideten täglich 18 Stunden. Zur Schätzung der Futteraufnahme wurde die n-AlkanDoppelmarkermethode benutzt. Für die Berechnung der Futterauswahl wurden Alkane, langkettige Alkohole und langkettige Fettsäuren als Markergruppen herangezogen. Die Anteile an Lolium perenne, Dactylis glomerata, anderen Gräsern, Trifolium repens, Taraxacum officinale und andere Pflanzen wurden mit allen Kombinationen der Markergruppen berechnet. Zudem wurde das Fress- und Wiederkauverhalten sowie die Aktivität mit Pedometern aufgezeichnet. Weil die HCH grösser waren, nahmen sie tendenziell mehr Futter auf, ohne signifikant mehr energiekorrigierte Milch (ECM) zu produzieren als die HNZ. Es bestand kein Unterschied zwischen den zwei Kuhtypen im Verhältnis ECM pro Futter-Trockensubstanz. Ausser für die Fressdauer traten keine signifikanten Unterschiede zwischen den zwei Kuhtypen im Fressund Wiederkauverhalten sowie für die Aktivität auf. Die Berechnungen der Rationsanteile mit dem «nnls» Paket für R wurde mit Daten aus der Literatur überprüft. Die gewählte Vorgehensweise ergab in unserer Studie realistische Futteranteile nahe der botanischen Zusammensetzung. Dabei unterschieden sich die Rationsanteile je nach Markerkombination und je nach Kuh. Ohne Einfluss auf die Rationsanteile blieben der Kuhtyp, die Messwoche und die Interaktion Kuhtyp und Messwoche. Schliesslich eröffnen sich Fragen wie z.B. die Relation zwischen individueller Futterauswahl der Kühe zur ihrer Nährstoffverwertung ist und wie den Bedürfnissen der Milchkühe genauer angepasste Pflanzenbestände die Nährstoffverwertung verbessern würden

Characterizing the spin state of an atomic ensemble using the magneto-optical resonance method

Quantum information protocols utilizing atomic ensembles require preparation of a coherent spin state (CSS) of the ensemble as an important starting point. We investigate the magneto-optical resonance method for characterizing a spin state of cesium atoms in a paraffin coated vapor cell. Atoms in a constant magnetic field are subject to an off-resonant laser beam and an RF magnetic field. The spectrum of the Zeeman sub-levels, in particular the weak quadratic Zeeman effect, enables us to measure the spin orientation, the number of atoms, and the transverse spin coherence time. Notably the use of 894nm pumping light on the D1-line, ensuring the state F=4, m_F=4 to be a dark state, helps us to achieve spin orientation of better than 98%. Hence we can establish a CSS with high accuracy which is critical for the analysis of the entangled states of atoms.Comment: 12 pages ReVTeX, 6 figures, in v2 added ref. and corrected typo

Collapse and revival of oscillations in a parametrically excited Bose-Einstein condensate in combined harmonic and optical lattice trap

In this work, we study parametric resonances in an elongated cigar-shaped BEC in a combined harmonic trap and a time dependent optical lattice by using numerical and analytical techniques. We show that there exists a relative competition between the harmonic trap which tries to spatially localize the BEC and the time varying optical lattice which tries to delocalize the BEC. This competition gives rise to parametric resonances (collapse and revival of the oscillations of the BEC width). Parametric resonances disappear when one of the competing factors i.e strength of harmonic trap or the strength of optical lattice dominates. Parametric instabilities (exponential growth of Bogoliubov modes) arise for large variations in the strength of the optical lattice.Comment: 9 pages, 20 figure

Reversibility of continuous-variable quantum cloning

We analyze a reversibility of optimal Gaussian $1\to 2$ quantum cloning of a coherent state using only local operations on the clones and classical communication between them and propose a feasible experimental test of this feature. Performing Bell-type homodyne measurement on one clone and anti-clone, an arbitrary unknown input state (not only a coherent state) can be restored in the other clone by applying appropriate local unitary displacement operation. We generalize this concept to a partial LOCC reversal of the cloning and we show that this procedure converts the symmetric cloner to an asymmetric cloner. Further, we discuss a distributed LOCC reversal in optimal $1\to M$ Gaussian cloning of coherent states which transforms it to optimal $1\to M'$ cloning for $M'<M$. Assuming the quantum cloning as a possible eavesdropping attack on quantum communication link, the reversibility can be utilized to improve the security of the link even after the attack.Comment: 7 pages, 5 figure

Narrowband frequency tunable light source of continuous quadrature entanglement

We report the observation of non-classical quantum correlations of continuous light variables from a novel type of source. It is a frequency non-degenerate optical parametric oscillator below threshold, where signal and idler fields are separated by 740MHz corresponding to two free spectrum ranges of the parametric oscillator cavity. The degree of entanglement observed, - 3.8 dB, is the highest to-date for a narrowband tunable source suitable for atomic quantum memory and other applications in atomic physics. Finally we use the latter to visualize the Einstein-Podolsky-Rosen paradox.Comment: 11 pages, 9 figures, LaTe

CPT spectroscopy on low-temperature sealed MEMS rubidium vapour cells

In recent years there has been a strong effort to reduce the size and power consumption of vapour cell atomic clocks [1,2]. The progress in this direction is driven by several factors such as the use low power laser diodes (VCSEL), Coherent Population Trapping resonances (CPT), and micro-fabricated (MEMS) alkali-vapour cells. Here the micro-fabrication of vapour cells has proven a challenging task. All results reported on this task use anodic bonding at high-temperatures (>300°C) to seal the cell [3]. However, the low melting point and high vapour pressure of the alkali-metal combined with long bonding-times (>1hour) complicate this process. We have recently developed a low temperature (~150°C) sealing technique with fast process time (<1min) based on soldering [4]. We report here on the measurement of 85Rb σ+ CPT resonance in low temperature sealed MEMS-fabricated vapour cells containing natural rubidium and buffer gas. The resonance is recorded on the rubidium D1-line (795nm) using a circular polarized and current-modulated VCSEL. We record the resonance shift, linewidth and amplitude as function of several experimental parameters such as light intensity, cell-temperature, and buffer gas pressure- and mixture. In addition we perform noise measurements on the resonance signal to characterize the cell for clock-applications. Preliminary results show a contrast of 1.7% and linewidth of 900Hz for a 4mm long cell with 70mbar of nitrogen buffer gas. Finally we present and characterize two problems related to the application of 85Rb resonance in clock-applications. First, the low modulation frequency of the VCSEL (1.5GHz) leads to a strong asymmetry in the first order sideband spectrum due to the combined effect of AM- and FM modulation. Second, the buffer gas broadening of the absorption spectrum combined with the small separation between VCSEL carrier and sideband reduces the CPT contrast due to off-resonant absorption. We demonstrate that the impact of both these effects can be reduced by modulating the VCSEL at 3GHz and probing the CPT resonance with the carrier and first order sideband. We acknowledge support from the European Space Agency ESA (ESTEC contract number 20794/07/NL/GLC), the Conference Universitaire Suisse CUS (project CIMENT), the Swiss Space Office SSO, and SpectraTime SA (Neuchâtel, Switzerland)

The Shadows of the Past

We examined associations between two orientations based on historical group trauma, a form of enduring group victimhood (Perpetual Ingroup Victimhood Orientation [PIVO]) and the belief that one’s group might itself become a victimizer (Fear of Victimizing [FOV]), and attitudes, cognitions, and emotions related to intergroup conflicts. PIVO was positively and FOV was negatively related to aggressive attitudes and emotions toward the outgroup (Studies 1a-1c, Israeli–Palestinian conflict), and to the attribution of responsibility for a series of hostilities to the outgroup (Study 3, Israeli–Palestinian conflict). PIVO was negatively and FOV positively related to support for forgiveness and reconciliation (Study 2, Northern Ireland conflict). In Experimental Study 4, FOV predicted greater accuracy in remembering harm, regardless of victims’ group identity, whereas PIVO was associated with reduced accuracy only when victims were Palestinians (outgroup members). Taken together, these findings indicate that both orientations have a significant impact on intergroup conflicts and their resolution

Quantum memory for entangled two-mode squeezed states

A quantum memory for light is a key element for the realization of future quantum information networks. Requirements for a good quantum memory are (i) versatility (allowing a wide range of inputs) and (ii) true quantum coherence (preserving quantum information). Here we demonstrate such a quantum memory for states possessing Einstein-Podolsky-Rosen (EPR) entanglement. These multi-photon states are two-mode squeezed by 6.0 dB with a variable orientation of squeezing and displaced by a few vacuum units. This range encompasses typical input alphabets for a continuous variable quantum information protocol. The memory consists of two cells, one for each mode, filled with cesium atoms at room temperature with a memory time of about 1msec. The preservation of quantum coherence is rigorously proven by showing that the experimental memory fidelity 0.52(2) significantly exceeds the benchmark of 0.45 for the best possible classical memory for a range of displacements.Comment: main text 5 pages, supplementary information 3 page

A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard

The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agrees with that from free np scattering, we conclude that our investigation of the nn FSI done simultaneously and under identical conditions gives the correct value for a_nn. Our value for a_nn is in agreement with that obtained in pion-deuteron capture measurements but disagrees with values obtained from earlier nd breakup studies.Comment: 4 pages and 3 figure

Superfluid to Mott insulator transition in one, two, and three dimensions

We have created one-, two-, and three-dimensional quantum gases and study the superfluid to Mott insulator transition. Measurements of the transition using Bragg spectroscopy show that the excitation spectra of the low-dimensional superfluids differ significantly from the three-dimensional case