Symposium 4: Food innovations to promote nutritional wellbeing Probiotics for infants and young children

The intestinal microflora has an important impact on life and has important implications for health in every human being. Probiotics are life micro-organisms that might have, after consumption in specific quantities, an impact on human health. The mechanisms by which probiotics confer their health effects in general terms will be discussed. Specific reports on the probiotics Bifidobacterium animalis and Lactobacillus paracasei consistently contain statements that both shortterm and long-term feeding of these probiotics to children aged 1-3 years, infants aged 0-12 months, and even to pre-term infants is not associated with differences in growth, stooling/ defecation patterns, behavioural aspects or history of illness compared to control groups. With regard to beneficial clinical effects with probiotics in general, the consistent and world-wide emergence of data that indicate beneficial clinical effects of some probiotic strains like Bifidobacterium animalis and Lactobacillus paracasei in infants and children cannot be ignored. Especially their potential benefit in preventing or ameliorating gastrointestinal inflammation and diarrhoea appears to be a realistic notion. First, inflammatory effects should translate into enhanced immunity, diminishment of existing unresponsive inflammation and correction of existing immunological defects. Second, enzymatic activities of probiotic bacteria might correct functional deficits induced by infectious diseases. Although it is unclear what the relevance is at this moment in time, some probiotics strains clearly show immune modulating effects in infants

Detection and control of individual nuclear spins using a weakly coupled electron spin

We experimentally isolate, characterize and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multi-pulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused by the rest of the spin bath. We are able to address nuclear spins with interaction strengths that are an order of magnitude smaller than the electron spin dephasing rate. Our results provide a route towards tomography with single-nuclear-spin sensitivity and greatly extend the number of available quantum bits for quantum information processing in diamond

Adiabatic dynamical-decoupling-based control of nuclear spin registers

The use of the nuclear spins surrounding electron spin qubits as quantum registers and long-lived memories opens the way to new applications in quantum information and biological sensing. Hence, there is a need for generic and robust forms of control of the nuclear registers. Although adiabatic gates are widely used in quantum information, they can become too slow to outpace decoherence. Here, we introduce a technique whereby adiabatic gates arise from the dynamical decoupling protocols that simultaneously extend coherence. We illustrate this pulse-based adiabatic control for nuclear spins around NV centers in diamond. We obtain a closed-form expression from Landau-Zener theory and show that it reliably describes the dynamics. By identifying robust Floquet states, we show that the technique enables polarization, one-shot flips, and state storage for nuclear spins. These results introduce a control paradigm that combines dynamical decoupling with adiabatic evolution

One-second coherence for a single electron spin coupled to a multi-qubit nuclear-spin environment

Single electron spins coupled to multiple nuclear spins provide promising multi-qubit registers for quantum sensing and quantum networks. The obtainable level of control is determined by how well the electron spin can be selectively coupled to, and decoupled from, the surrounding nuclear spins. Here we realize a coherence time exceeding a second for a single electron spin through decoupling sequences tailored to its microscopic nuclear-spin environment. We first use the electron spin to probe the environment, which is accurately described by seven individual and six pairs of coupled carbon-13 spins. We develop initialization, control and readout of the carbon-13 pairs in order to directly reveal their atomic structure. We then exploit this knowledge to store quantum states for over a second by carefully avoiding unwanted interactions. These results provide a proof-of-principle for quantum sensing of complex multi-spin systems and an opportunity for multi-qubit quantum registers with long coherence times

Robust quantum-network memory using decoherence-protected subspaces of nuclear spins

The realization of a network of quantum registers is an outstanding challenge in quantum science and technology. We experimentally investigate a network node that consists of a single nitrogen-vacancy (NV) center electronic spin hyperfine-coupled to nearby nuclear spins. We demonstrate individual control and readout of five nuclear spin qubits within one node. We then characterize the storage of quantum superpositions in individual nuclear spins under repeated application of a probabilistic optical inter-node entangling protocol. We find that the storage fidelity is limited by dephasing during the electronic spin reset after failed attempts. By encoding quantum states into a decoherence-protected subspace of two nuclear spins we show that quantum coherence can be maintained for over 1000 repetitions of the remote entangling protocol. These results and insights pave the way towards remote entanglement purification and the realisation of a quantum repeater using NV center quantum network nodes

Directional emission of light from a nano-optical Yagi-Uda antenna

The plasmon resonance of metal nanoparticles can enhance and direct light from optical emitters in much the same way that radio frequency (RF) antennas enhance and direct the emission from electrical circuits. In the RF regime, a typical antenna design for high directivity is the Yagi-Uda antenna, which basically consists of a one-dimensional array of antenna elements driven by a single feed element. Here, we present the experimental demonstration of directional light emission from a nano-optical Yagi-Uda antenna composed of an array of appropriately tuned gold nanorods. Our results indicate that nano-optical antenna arrays are a simple but efficient tool for the spatial control of light emission.Comment: 4 pages, including 4 figure