Exportkansen op de Franse biologische markt

De markt voor biologische producten groeit in Frankrijk. Dit kan kansen bieden voor de Nederlandse export. Export bestaat al wel, maar is nog beperkt. In een onderzoek is bekeken of en hoe Nederlandse toeleveranciers hun toegang tot de Franse markt kunnen vergroten

Vleesafzet van biologische beren : een opiniepeiling in Duitsland en het Verenigd Koninkrijk

The organic pig sector in the Netherlands wants to put an end to the castration of boar piglets as soon as possible. Since the Netherlands exports organic meat, it is important to be aware of the attitude of buyers abroad with regard to meat from intact male pigs. This small-scale opinion poll provides insight into this

An experimental proposal to study collapse of the wave function in travelling-wave parametric amplifiers

The read-out of a microwave qubit state occurs using an amplification chain that enlarges the quantum state to a signal detectable with a classical measurement apparatus. However, at what point in this process did we really `measure' the quantum state? In order to investigate whether the `measurement' takes place in the amplification chain, we propose to construct a microwave interferometer that has a parametric amplifier added to each of its arms. Feeding the interferometer with single photons, the visibility depends on the gain of the amplifiers and whether a measurement collapse has taken place during the amplification process. We calculate the interference visibility as given by standard quantum mechanics as a function of gain, insertion loss and temperature and find a magnitude of $1/3$ in the limit of large gain without taking into account losses. This number reduces to $0.26$ in case the insertion loss of the amplifiers is $2.2$ dB at a temperature of $50$ mK. We show that if the wave function collapses within the interferometer, we will measure a reduced visibility compared to the prediction from standard quantum mechanics once this collapse process sets in.Comment: 21 pages and 23 figures (including appendices and subfigures). v4: Abstract and introduction rewritten and note on stochasticity of quantum state collapse added to section 6. v5: no content changes w.r.t. v

Concurrentiekracht biologisch varkensvlees : een internationale vergelijking

Nederland is een sterke speler in de productie van biologisch varkensvlees in Noordwest-Europa. Het niveau van de productiekosten in de biologische varkenshouderij in Duitsland en Denemarken ligt lager dan in Nederland. Denemarken is een geduchte concurrent. Maar door een efficiënte organisatie van de productieketen is Nederland in staat rendabel te concurreren. Afzet naar Duitsland en het VK vergt een specifieke aanpak

Nanopositioning of a diamond nanocrystal containing a single NV defect center

Precise control over the position of a single quantum object is important for many experiments in quantum science and nanotechnology. We report on a technique for high-accuracy positioning of individual diamond nanocrystals. The positioning is done with a home-built nanomanipulator under real-time scanning electron imaging, yielding an accuracy of a few nanometers. This technique is applied to pick up, move and position a single NV defect center contained in a diamond nanocrystal. We verify that the unique optical and spin properties of the NV center are conserved by the positioning process.Comment: 3 pages, 3 figures; high-resolution version available at http://www.ns.tudelft.nl/q

A method for mechanical generation of radio frequency fields in nuclear magnetic resonance force microscopy

We present an innovative method for magnetic resonance force microscopy (MRFM) with ultra-low dissipation, by using the higher modes of the mechanical detector as radio frequency (rf) source. This method allows MRFM on samples without the need to be close to an rf source. Furthermore, since rf sources require currents that give dissipation, our method enables nuclear magnetic resonance experiments at ultra-low temperatures. Removing the need for an on-chip rf source is an important step towards a MRFM which can be widely used in condensed matter physics.Comment: 7 pages, 5 figures, to be submitted to Physical Review Applie

Determination of the complex microwave photoconductance of a single quantum dot

A small quantum dot containing approximately 20 electrons is realized in a two-dimensional electron system of an AlGaAs/GaAs heterostructure. Conventional transport and microwave spectroscopy reveal the dot's electronic structure. By applying a coherently coupled two-source technique, we are able to determine the complex microwave induced tunnel current. The amplitude of this photoconductance resolves photon-assisted tunneling (PAT) in the non-linear regime through the ground state and an excited state as well. The out-of-phase component (susceptance) allows to study charge relaxation within the quantum dot on a time scale comparable to the microwave beat period.Comment: 5.5 pages, 6 figures, accepted by Phys. Rev. B (Jan. B15 2001

Deterministic nano-assembly of a coupled quantum emitter - photonic crystal cavity system

The interaction of a single quantum emitter with its environment is a central theme in quantum optics. When placed in highly confined optical fields, such as those created in optical cavities or plasmonic structures, the optical properties of the emitter can change drastically. In particular, photonic crystal (PC) cavities show high quality factors combined with an extremely small mode volume. Efficiently coupling a single quantum emitter to a PC cavity is challenging because of the required positioning accuracy. Here, we demonstrate deterministic coupling of single Nitrogen-Vacancy (NV) centers to high-quality gallium phosphide PC cavities, by deterministically positioning their 50 nm-sized host nanocrystals into the cavity mode maximum with few-nanometer accuracy. The coupling results in a 25-fold enhancement of NV center emission at the cavity wavelength. With this technique, the NV center photoluminescence spectrum can be reshaped allowing for efficient generation of coherent photons, providing new opportunities for quantum science.Comment: 13 pages, 4 figure

Overwegingen bij alternatieve kadaverlogistiek in Nederland; Consequenties van het verruimen van de bewaarperiode van kadavers

Signalen uit de veehouderij geven aan dat het voor sommige veehouders aantrekkelijk zou kunnen zijn om de ophaalfrequentie van kadavers te verminderen. Het ministerie van EZ heeft het LEI daarom gevraagd om een oriëntatie van voor- en nadelen van langer koelen en invriezen van kadavers en kadavermateriaal en de consequenties daarvan te bestuderen ten aanzien van de risico's voor dier- en volksgezondheid, handhaafbaarheid, transportbewegingen, verbruik koelingsenergie, verwerkingsmogelijkheden van gekoeld en ingevroren materiaal. Doel van het onderzoek is het in kaart brengen van consequenties van het verruimen van de bewaarperiode van kadavers en kadavermateriaal. EZ heeft behoefte om de voordelen te concretiseren en af te wegen tegen de nadelen, ten behoeve van een eventuele toekomstige beleidskeuze. Het ministerie wil er zeker van zijn dat een nieuwe systematiek geen extra risico's met zich meebrengt voor dier- en volksgezondheid

Probing the magnetic moment of FePt micromagnets prepared by Focused Ion Beam milling

We investigate the degradation of the magnetic moment of a 300 nm thick FePt film induced by Focused Ion Beam (FIB) milling. A $1~\mu \mathrm{m} \times 8~\mu \mathrm{m}$ rod is milled out of a film by a FIB process and is attached to a cantilever by electron beam induced deposition. Its magnetic moment is determined by frequency-shift cantilever magnetometry. We find that the magnetic moment of the rod is $\mu = 1.1 \pm 0.1 \times 10 ^{-12} \mathrm{Am}^2$, which implies that 70% of the magnetic moment is preserved during the FIB milling process. This result has important implications for atom trapping and magnetic resonance force microscopy (MRFM), that are addressed in this paper.Comment: 4 pages, 4 figure