Wohlergehen von Bioschweinen und Umweltwirkungen – (k)ein Widerspruch? Haltungssysteme der Bio-Schweine in Europa im Vergleich

Das Haltungssystem hat Einfluss auf Gesundheit, Wohlergehen und Umweltauswirkungen von Bioschweinen; Freilandhaltung ist grundsätzlich vorteilhaft für das Tierwohlergehen und teilweise Freilandhaltung hinsichtlich Umweltwirkung. Durch gutes Management können jedoch grundsätzlich in jedem System gute Ergebnisse erzielt werden. Die Ergebnisse der Studie können als Basis der Weiterentwicklung der Bioschweinehaltungssysteme in Europa dienen. Sofern die Voraussetzungen am Betrieb gegeben sind (z.B. ausreichend Flächen) und gutes Management gewährleistet ist, können Stallhaltungsbetriebe das Tierwohlergehen steigern, indem beispielsweise die Sauen saisonal im Freiland gehalten werden. Andererseits kann die Umweltwirkung mancher Freilandbetriebe voraussichtlich reduziert werden, indem Mastschweine teilweise im Stall gehalten werden. Das Haltungssystem sollte jedenfalls den Möglichkeiten des Betriebes entsprechen

Quantitative modeling of superconducting planar resonators with improved field homogeneity for electron spin resonance

We present three designs for planar superconducting microwave resonators for electron spin resonance (ESR) experiments. We implement finite element simulations to calculate the resonance frequency and quality factors as well as the three-dimensional microwave magnetic field distribution of the resonators. One particular resonator design offers an increased homogeneity of the microwave magnetic field while the other two show a better confinement of the mode volume. We extend our model simulations to calculate the collective coupling rate between a spin ensemble and a microwave resonator in the presence of an inhomogeneous magnetic resonator field. Continuous-wave ESR experiments of phosphorus donors in $^\mathrm{nat}$Si demonstrate the feasibility of our resonators for magnetic resonance experiments. We extract the collective coupling rate and find a good agreement with our simulation results, corroborating our model approach. Finally, we discuss specific application cases for the different resonator designs

Maser threshold characterization by resonator Q-factor tuning

Whereas the laser is nowadays an ubiquitous technology, applications for its microwave analog, the maser, remain highly specialized, despite the excellent low-noise microwave amplification properties. The widespread application of masers is typically limited by the need of cryogenic temperatures. The recent realization of a continuous-wave room-temperature maser, using NV− centers in diamond, is a first step towards establishing the maser as a potential platform for microwave research and development, yet its design is far from optimal. Here, we design and construct an optimized setup able to characterize the operating space of a maser using NV− centers. We focus on the interplay of two key parameters for emission of microwave photons: the quality factor of the microwave resonator and the degree of spin level-inversion. We characterize the performance of the maser as a function of these two parameters, identifying the parameter space of operation and highlighting the requirements for maximal continuous microwave emission

Nonlinear magnon polaritons

We experimentally and theoretically demonstrate that nonlinear spin-wave interactions suppress the hybrid magnon-photon quasiparticle or "magnon polariton" in microwave spectra of an yttrium iron garnet film detected by an on-chip split-ring resonator. We observe a strong coupling between the Kittel and microwave cavity modes in terms of an avoided crossing as a function of magnetic fields at low microwave input powers, but a complete closing of the gap at high powers. The experimental results are well explained by a theoretical model including the three-magnon decay of the Kittel magnon into spin waves. The gap closure originates from the saturation of the ferromagnetic resonance above the Suhl instability threshold by a coherent back reaction from the spin waves.Comment: 6 page

Spin resonance linewidths of bismuth donors in silicon coupled to planar microresonators

Ensembles of bismuth donor spins in silicon are promising storage elements for microwave quantum memories due to their long coherence times which exceed seconds. Operating an efficient quantum memory requires achieving critical coupling between the spin ensemble and a suitable high-quality factor resonator -- this in turn requires a thorough understanding of the lineshapes for the relevant spin resonance transitions, particularly considering the influence of the resonator itself on line broadening. Here, we present pulsed electron spin resonance measurements of ensembles of bismuth donors in natural silicon, above which niobium superconducting resonators have been patterned. By studying spin transitions across a range of frequencies and fields we identify distinct line broadening mechanisms, and in particular those which can be suppressed by operating at magnetic-field-insensitive `clock transitions'. Given the donor concentrations and resonator used here, we measure a cooperativity $C\sim 0.2$ and based on our findings we discuss a route to achieve unit cooperativity, as required for a quantum memory

High cooperativity in coupled microwave resonator ferrimagnetic insulator hybrids

We report the observation of strong coupling between the exchange-coupled spins in gallium-doped yttrium iron garnet and a superconducting coplanar microwave resonator made from Nb. The measured coupling rate of 450 MHz is proportional to the square-root of the number of exchange-coupled spins and well exceeds the loss rate of 50 MHz of the spin system. This demonstrates that exchange coupled systems are suitable for cavity quantum electrodynamics experiments, while allowing high integration densities due to their extraordinary high spin densities. Our results furthermore show, that experiments with multiple exchange-coupled spin systems interacting via a single resonator are within reach.Comment: 5 pages, 3 figure

Strain in heterogeneous quantum devices with atomic layer deposition

Abstract: We investigated the use of dielectric layers produced by atomic layer deposition (ALD) as an approach to strain mitigation in composite silicon/superconductor devices operating at cryogenic temperatures. We show that the addition of an ALD layer acts to reduce the strain of spins closest to silicon/superconductor interface where strain is highest. We show that appropriately biasing our devices at the hyperfine clock transition of bismuth donors in silicon, we can remove strain broadening and that the addition of ALD layers left T 2 (or temporal inhomogeneities) unchanged in these natural silicon devices