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

Effect of irrigation-induced erosion on the degradation of soils in river valleys of the alpine Pamir

© 2015, Pleiades Publishing, Ltd. Results of a study were analzyed, which was conducted on the arable stony alpine soils in the Gunt River valley and the upper Panj River. Such soils are occurring in different regions of the Western Pamirs. The physicochemical properties of the soils were studied using conventional methods, and the degradation rate of the soil cover was determined using the radiocesium method. Low contents of humus (2–3° with furrow irrigation, is the main anthropogenic factor of soil degradation. The lower content of humus in the soils of the Panj River valley is due to the larger portion of slopes >3° with furrow irrigation, on which also maximum rates of irrigation-induced erosion (>30 ha/year) were observed

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

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

Effect of irrigation-induced erosion on the degradation of soils in river valleys of the alpine Pamir

© 2015, Pleiades Publishing, Ltd. Results of a study were analzyed, which was conducted on the arable stony alpine soils in the Gunt River valley and the upper Panj River. Such soils are occurring in different regions of the Western Pamirs. The physicochemical properties of the soils were studied using conventional methods, and the degradation rate of the soil cover was determined using the radiocesium method. Low contents of humus (2–3° with furrow irrigation, is the main anthropogenic factor of soil degradation. The lower content of humus in the soils of the Panj River valley is due to the larger portion of slopes >3° with furrow irrigation, on which also maximum rates of irrigation-induced erosion (>30 ha/year) were observed

Effect of irrigation-induced erosion on the degradation of soils in river valleys of the alpine Pamir

© 2015, Pleiades Publishing, Ltd. Results of a study were analzyed, which was conducted on the arable stony alpine soils in the Gunt River valley and the upper Panj River. Such soils are occurring in different regions of the Western Pamirs. The physicochemical properties of the soils were studied using conventional methods, and the degradation rate of the soil cover was determined using the radiocesium method. Low contents of humus (2–3° with furrow irrigation, is the main anthropogenic factor of soil degradation. The lower content of humus in the soils of the Panj River valley is due to the larger portion of slopes >3° with furrow irrigation, on which also maximum rates of irrigation-induced erosion (>30 ha/year) were observed