Entanglement-enhanced probing of a delicate material system

Quantum metrology uses entanglement and other quantum effects to improve the sensitivity of demanding measurements. Probing of delicate systems demands high sensitivity from limited probe energy and has motivated the field's key benchmark-the standard quantum limit. Here we report the first entanglement-enhanced measurement of a delicate material system. We non-destructively probe an atomic spin ensemble by means of near-resonant Faraday rotation, a measurement that is limited by probe-induced scattering in quantum-memory and spin-squeezing applications. We use narrowband, atom-resonant NOON states to beat the standard quantum limit of sensitivity by more than five standard deviations, both on a per-photon and per-damage basis. This demonstrates quantum enhancement with fully realistic loss and noise, including variable-loss effects. The experiment opens the way to ultra-gentle probing of single atoms, single molecules, quantum gases and living cells.Comment: 7 pages, 8 figures; Nature Photonics, advance online publication, 16 December 201

Adsorption of Diclofenac and PFBS on Hair Keratin Dimer

Environmental pollution by man-made toxic and persistent organic compounds, found throughout the world in surface and groundwater, has various negative effects on aquatic life systems and even humans. Therefore, it is important to develop and improve water treatment technologies capable of removing such substances from wastewater or purifying drinking water. The two substances investigated are the widely used painkiller diclofenac and a member of the class of "forever chemicals", perfluorobutane sulfonate. Both are known to have serious negative effects on living organisms, especially under long-term exposure, and are detectable in human hair, suggesting adsorption to a part of the hair fiber complex. In this study, a human hair keratin dimer is investigated for its ability to absorb diclofenac and perfluorobutane sulfonate. Initial predictions for binding sites are obtained via molecular docking and subjected to molecular dynamics simulations for more than $1$ $\mathrm{\mu s}$. The binding affinities obtained by the linear interaction energy method are high enough to motivate further research on human hair keratins as a sustainable, low-cost, and easily allocatable filtration material.Comment: 19 pages, 8 figures, 2 table

Bright filter-free source of indistinguishable photon pairs

We demonstrate a high-brightness source of pairs of indistinguishable photons based on a type-II phase-matched doubly-resonant optical parametric oscillator operated far below threshold. The cavity-enhanced down-conversion output of a PPKTP crystal is coupled into two single-mode fibers with a mode coupling efficiency of 58%. The high degree of indistinguishability between the photons of a pair is demonstrated by a Hong-Ou-Mandel interference visibility of higher than 90% without any filtering at an instantaneous coincidence rate of 450 000 pairs/s per mW of pump power per nm of down-conversion bandwidth. For the degenerate spectral mode with a linewidth of 7 MHz at 795 nm a rate of 70 pairs/(s mW MHz) is estimated, increasing the spectral brightness for indistinguishable photons by two orders of magnitude compared to similar previous sources.Comment: 7 pages, 3 figure

Interaction-based quantum metrology showing scaling beyond the Heisenberg limit

Quantum metrology studies the use of entanglement and other quantum resources to improve precision measurement. An interferometer using N independent particles to measure a parameter X can achieve at best the "standard quantum limit" (SQL) of sensitivity {\delta}X \propto N^{-1/2}. The same interferometer using N entangled particles can achieve in principle the "Heisenberg limit" {\delta}X \propto N^{-1}, using exotic states. Recent theoretical work argues that interactions among particles may be a valuable resource for quantum metrology, allowing scaling beyond the Heisenberg limit. Specifically, a k-particle interaction will produce sensitivity {\delta}X \propto N^{-k} with appropriate entangled states and {\delta}X \propto N^{-(k-1/2)} even without entanglement. Here we demonstrate this "super-Heisenberg" scaling in a nonlinear, non-destructive measurement of the magnetisation of an atomic ensemble. We use fast optical nonlinearities to generate a pairwise photon-photon interaction (k = 2) while preserving quantum-noise-limited performance, to produce {\delta}X \propto N^{-3/2}. We observe super-Heisenberg scaling over two orders of magnitude in N, limited at large N by higher-order nonlinear effects, in good agreement with theory. For a measurement of limited duration, super-Heisenberg scaling allows the nonlinear measurement to overtake in sensitivity a comparable linear measurement with the same number of photons. In other scenarios, however, higher-order nonlinearities prevent this crossover from occurring, reflecting the subtle relationship of scaling to sensitivity in nonlinear systems. This work shows that inter-particle interactions can improve sensitivity in a quantum-limited measurement, and introduces a fundamentally new resource for quantum metrology

The potential of student narratives to enhance quality in higher education

University policies are increasingly developed with reference to students’ learning experiences, with a focus on the concept of the ‘student voice’. Yet the ‘student voice’ is difficult to define and emphasis is often placed on numerical performance indicators. A diverse student population has wide-ranging educational experiences, which may not be easily captured within the broad categories provided by traditional survey tools, which can drown out the rich, varied and gradual processes of individual development. There is no single tool that can be used to measure students’ experiences. This paper draws on findings from four narrative inquiry studies, carried out in the United Kingdom, Australia, South Africa and New Zealand, to illustrate how a narrative approach could be used to complement performance indicators. This provides a richer context for educators’ understanding of students’ experiences and for supporting and setting institutional agendas

Biological measurement beyond the quantum limit

Quantum noise places a fundamental limit on the per photon sensitivity attainable in optical measurements. This limit is of particular importance in biological measurements, where the optical power must be constrained to avoid damage to the specimen. By using non-classically correlated light, we demonstrated that the quantum limit can be surpassed in biological measurements. Quantum enhanced microrheology was performed within yeast cells by tracking naturally occurring lipid granules with sensitivity 2.4 dB beyond the quantum noise limit. The viscoelastic properties of the cytoplasm could thereby be determined with a 64% improved measurement rate. This demonstration paves the way to apply quantum resources broadly in a biological context

Detection of IL28B SNP DNA from Buccal Epithelial Cells, Small Amounts of Serum, and Dried Blood Spots

Background & Aims: Point mutations in the coding region of the interleukin 28 gene (rs12979860) have recently been identified for predicting the outcome of treatment of hepatitis C virus infection. This polymorphism detection was based on whole blood DNA extraction. Alternatively, DNA for genetic diagnosis has been derived from buccal epithelial cells (BEC), dried blood spots (DBS), and genomic DNA from serum. The aim of the study was to investigate the reliability and accuracy of alternative routes of testing for single nucleotide polymorphism allele rs12979860CC. Methods: Blood, plasma, and sera samples from 200 patients were extracted (400 mL). Buccal smears were tested using an FTA card. To simulate postal delay, we tested the influence of storage at ambient temperature on the different sources of DNA at five time points (baseline, 48 h, 6 days, 9 days, and 12 days) Results: There was 100 % concordance between blood, plasma, sera, and BEC, validating the use of DNA extracted from BEC collected on cytology brushes for genetic testing. Genetic variations in HPTR1 gene were detected using smear technique in blood smear (3620 copies) as well as in buccal smears (5870 copies). These results are similar to those for whole blood diluted at 1/10. A minimum of 0.04 mL, 4 mL, and 40 mL was necessary to obtain exploitable results respectively for whole blood, sera, and plasma. No significant variation between each time point was observed for the different sources of DNA. IL28B SNPs analysis at these different time points showed the same results using the four sources of DNA

Perceived managerial and leadership effectiveness in a Korean context: An indigenous qualitative study

Multinational corporations (MNCs) across the world have sent an increasing number of managers abroad to leverage unprecedented opportunities in the era of globalization. However, their failure rate has been above 33% for decades, resulting in substantial costs (Puck, Kittler, & Wright, 2008). One of the primary reasons for this failure is a lack of understanding of the national and organizational cultures within the host countries (Festing & Maletzky, 2011). For example, while a number of MNCs have entered the Korean market, several such as Yahoo, Motorola, and Walmart have failed and withdrawn due to the companies’ lack of adjustment to the Korean cultural context (Choe, 2006; Woo, 2013). In spite of the significance of culturally embedded practices, most researchers who have explored management and leadership in Asian countries, whether they were Western or indigenous researchers, have implemented studies using extant Western management and leadership theories derived within the Western cultural context (Leung, 2007; Tsui, 2006). Numerous scholars have claimed that this could be problematic because the findings of such studies may not be applicable to non-Western countries (Li, 2012; Liden & Antonakis, 2009), and may fail to provide insights and understanding of novel contexts or to reveal indigenous aspects of management and leadership (Tsui, 2007). Consequently, there have been increasing calls for indigenous management and leadership research within Asian countries (see Li et al., 2014; Lyles, 2009; Tsui, 2004; Wolfgramm, Spiller, & Voyageur, 2014). Over the past 30 years, managerial effectiveness and leadership effectiveness have been substantially neglected areas of management research (Noordegraaf & Stewart, 2000; Yukl, Gordon, & Taber, 2002). In addition, there has been little agreement on what specific behaviors distinguish effective managers from ineffective ones. Furthermore, more research is needed to examine the managerial and leadership behaviors that are critical for shaping the performance of individuals, groups and organizations (see Borman & Brush, 1993; Cammock, Nilakant & Dakin, 1995; Mumford, 2011; Noordegraaf & Stewart, 2000; Yukl et al., 2002). While most of the research related to managerial and leadership effectiveness has been conducted in the U.S., the few notable non-U.S. studies include that of Cammock et al. (1995) in New Zealand who developed a behavioral lay model of managerial effectiveness using the repertory grid technique. Another notable exception is the cumulative series of perceived managerial and leadership effectiveness studies conducted by Hamlin with various indigenous co-researchers in Western and non-Western countries (see Hamlin & Patel, 2012; Ruiz, Wang, & Hamlin, 2013) using Flanagan’s (1954) critical incident technique (CIT)