Nature Physics January Issue

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TABLE OF CONTENTS January 2016 Volume 12, Issue 1 Editorial Correspondence Commentaries Thesis Books and Arts Research Highlights News and Views Letters Articles Measure for Measure Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement An open access, online-only, multidisciplinary research journal dedicated to publishing the most important scientific advances in the life sciences, physical sciences, and engineering fields that are facilitated by spaceflight and analogue platforms. Explore the benefits of submitting your next research article.    Focus on Thermometry The concept of temperature pervades the laws of physics. This Focus highlights various aspects of thermometry, from the (re)definition of the kelvin to ways of measuring temperature — from pK to MK — documenting some compelling physics along the way. Focus Thermometry Editorial Top Focus on Thermometry The art of measurement   p1 doi:10.1038/nphys3640 With a dedicated monthly column, Nature Physics draws attention to metrology. And a set of Commentaries in this issue focuses on various aspects of thermometry. Correspondence Top Questioning universal decoherence due to gravitational time dilation   p2 Yuri Bonder, Elias Okon and Daniel Sudarsky doi:10.1038/nphys3573 See also: Correspondence by Pikovski et al. Reply to 'Questioning universal decoherence due to gravitational time dilation'   pp2 - 3 Igor Pikovski, Magdalena Zych, Fabio Costa and Časlav Brukner doi:10.1038/nphys3650 See also: Correspondence by Bonder et al. Commentaries Top Focus on Thermometry The new system of units   pp4 - 7 Joachim Fischer and Joachim Ullrich doi:10.1038/nphys3612 The redefinition of several physical base units planned for 2018 requires precise knowledge of the values of certain fundamental physical constants. Scientists are working hard to meet the deadlines for realizing the ultimate International System of Units. Focus on Thermometry Advances in thermometry   pp7 - 11 Michael R. Moldover, Weston L. Tew and Howard W. Yoon doi:10.1038/nphys3618 The past 25 years have seen tremendous progress in thermometry across the moderate temperature range of 1 K to 1,235 K. Various primary thermometers, based on a wide range of different physics, have uncovered errors in the International Temperature Scale of 1990, and set the stage for the planned redefinition of the kelvin. Focus on Thermometry Physics at its coolest   pp11 - 14 Juha Tuoriniemi doi:10.1038/nphys3616 In the quest for ever-lower temperatures, making new discoveries and overcoming technical challenges go hand in hand - and push the limits of thermometry standardization. Focus on Thermometry As hot as it gets   pp14 - 17 Didier Mazon, Christel Fenzi and Roland Sabot doi:10.1038/nphys3625 Sustaining and measuring high temperatures in fusion plasmas is a challenging task that requires different heating systems and diagnostic tools. Information on the spatial distribution of temperature is one of the key elements for improving and controlling plasma performance. Thesis Top Transition to turbulence   p18 Mark Buchanan doi:10.1038/nphys3630 Books and Arts Top Cosmology in the dark   p19 Yiannis Tsamis reviews The Unknown Universe: A New Exploration of Time, Space, and Modern Cosmology by Stuart Clark doi:10.1038/nphys3623 Research Highlights Top Quantum mechanics: The lone traveller | Cosmology: X marks the spot | Topological phases: Call the tune | Biomaterials: Shell stress | Cerenkov radiation: Quantum matters News and Views Top Quantum engineering: Turn to the dark side   pp21 - 22 Yuimaru Kubo doi:10.1038/nphys3582 Coherent population trapping in 'dark states', a well-known and much-used phenomenon in atomic physics, can also be observed in a superconducting qubit and a single nuclear spin in diamond. See also: Article by Novikov et al. High-temperature superconductivity: A conventional conundrum   pp22 - 24 Ivan Božović doi:10.1038/nphys3626 High-temperature superconductivity in ultrathin films of iron selenide deposited on strontium titanate has been attributed to various exotic mechanisms. New experiments indicate that it may be conventional, with broader implications. See also: Letter by Shiogai et al. Fluid spintronics: Cause a stir   pp24 - 25 Igor Žutić and Alex Matos-Abiague doi:10.1038/nphys3572 The rotational motion of liquids can induce a flow of electron spins, and could enable ultra-small spin-hydrodynamic generators that operate with liquid metals. See also: Letter by Takahashi et al. Metastable skyrmions: Beat the heat   pp25 - 26 Dong Liang, Matthew J. Stolt and Song Jin doi:10.1038/nphys3547 Magnetic skyrmion lattices can be stabilized outside the narrow region where they are thermodynamically favoured by exploiting their topological protection. See also: Letter by Oike et al. nphys JOBS of the week More Science jobs from nphys EVENT The XXVII International Conference on Neutrino Physics and Astrophysics 03.07.16 London, UK More science events from Letters Top Cavity-mediated coupling of mechanical oscillators limited by quantum back-action   pp27 - 31 Nicolas Spethmann, Jonathan Kohler, Sydney Schreppler, Lukas Buchmann and Dan M. Stamper-Kurn doi:10.1038/nphys3515 Coupling two mechanical objects becomes tricky when they are quantum and can interact only through photons. An experiment now demonstrates such an optomechanical system with two separate atomic ensembles in the same optical cavity. Evidence of an odd-parity hidden order in a spin-orbit coupled correlated iridate   pp32 - 36 L. Zhao, D. H. Torchinsky, H. Chu, V. Ivanov, R. Lifshitz et al. doi:10.1038/nphys3517 The Mott insulator Sr2IrO4 is intensively studied because of its electronic similarity to the high-temperature cuprate superconductor La2CuO4. Now, spectroscopic experiments reveal evidence for a hidden order with odd-parity symmetry in this system. See also: Letter by Kim et al. Observation of a d-wave gap in electron-doped Sr2IrO4   pp37 - 41 Y. K. Kim, N. H. Sung, J. D. Denlinger and B. J. Kim doi:10.1038/nphys3503 Sr2IrO4 bears a striking electronic resemblance to the cuprate superconductors, except the iridate is an insulator. Introducing electrons into Sr2IrO4 leads to a d-wave gap, suggesting superconductivity or something equally exotic. See also: Letter by Zhao et al. Electric-field-induced superconductivity in electrochemically etched ultrathin FeSe films on SrTiO3 and MgO   pp42 - 46 J. Shiogai, Y. Ito, T. Mitsuhashi, T. Nojima and A. Tsukazaki doi:10.1038/nphys3530 Electric-field-induced superconductivity in samples of ultrathin FeSe grown on SrTiO3 and MgO substrates shows that the superconductivity is not an interfacial effect but is rather related to a charge imbalance of electrons and holes. See also: News and Views by Bozovic Thermodynamic signature of a magnetic-field-driven phase transition within the superconducting state of an underdoped cuprate   pp47 - 51 J. B. Kemper, O. Vafek, J. B. Betts, F. F. Balakirev, W. N. Hardy et al. doi:10.1038/nphys3502 Specific heat measurements up to 35 T provide thermodynamic evidence for a magnetic-field-driven phase transition within the superconducting dome of a copper-oxide-based superconductor. Spin hydrodynamic generation   pp52 - 56 R. Takahashi, M. Matsuo, M. Ono, K. Harii, H. Chudo et al. doi:10.1038/nphys3526 Magnetohydrodynamic generators use magnetic fields to convert the kinetic energy of conducting fluids into electricity. Fluid motion is now shown to generate spin currents, which can induce electric voltages without applying magnetic fields. See also: News and Views by Zutic & Matos-Abiague Remotely induced magnetism in a normal metal using a superconducting spin-valve   pp57 - 61 M. G. Flokstra, N. Satchell, J. Kim, G. Burnell, P. J. Curran et al. doi:10.1038/nphys3486 A switchable induced magnetic moment in a non-magnetic metal that is separated from a ferromagnet by a thick superconducting layer contradicts existing models. Interplay between topological and thermodynamic stability in a metastable magnetic skyrmion lattice   pp62 - 66 Hiroshi Oike, Akiko Kikkawa, Naoya Kanazawa, Yasujiro Taguchi, Masashi Kawasaki et al. doi:10.1038/nphys3506 Topological protection can stabilize states of matter, but for how long? By creating metastable magnetic skyrmion lattices, the interplay between topological and thermodynamic stability has now been probed experimentally. See also: News and Views by Liang et al. Brownian Carnot engine   pp67 - 70 I. A. Martínez, É. Roldán, L. Dinis, D. Petrov, J. M. R. Parrondo et al. doi:10.1038/nphys3518 Despite the simplicity of the Carnot cycle, realizing it at the microscale is complicated by the difficulty in implementing adiabatic processes. A clever solution subjects a charged particle to a noisy electrostatic force that mimics a thermal bath. Advertisement Have you read the following key article from npj Quantum Information?  Replicating the benefits of Deutschian closed timelike curves without breaking causality  npj Quantum Information is an online-only, open access journal providing important updates on quantum information research and theory, including quantum computing and communications. Visit www.nature.com/npjqi to explore latest research and to sign up to receive free article e-alerts.   Articles Top Entangling atomic spins with a Rydberg-dressed spin-flip blockade   pp71 - 74 Y.-Y. Jau, A. M. Hankin, T. Keating, I. H. Deutsch and G. W. Biedermann doi:10.1038/nphys3487 Tunable interactions in quantum many-body systems have practical applications in quantum technologies. The effective spin-dependent long-range interaction known as Rydberg dressing is now exploited to entangle a pair of ultracold neutral atoms. Raman coherence in a circuit quantum electrodynamics lambda system   pp75 - 79 S. Novikov, T. Sweeney, J. E. Robinson, S. P. Premaratne, B. Suri et al. doi:10.1038/nphys3537 Using an artificial three-level lambda system realized in a superconducting transmon qubit in a microwave cavity one can observe coherent population trapping, electromagnetically induced transparency and superluminal pulse propagation. See also: News and Views by Kubo Microscopic theory and quantum simulation of atomic heat transport   pp80 - 84 Aris Marcolongo, Paolo Umari and Stefano Baroni doi:10.1038/nphys3509 Heat transport is well described by the Green-Kubo formalism. Now, the formalism is combined with density-functional theory, enabling simulations of thermal conduction in systems that cannot be adequately modelled by classical interatomic potentials. Long-range p-d exchange interaction in a ferromagnet-semiconductor hybrid structure   pp85 - 91 V. L. Korenev, M. Salewski, I. A. Akimov, V. F. Sapega, L. Langer et al. doi:10.1038/nphys3497 Exchange interactions are typically short-ranged as they depend on wavefunction overlap, but a long-ranged exchange is now seen in a hybrid ferromagnet-semiconductor system, which may be mediated by elliptically polarized phonons. Characterization of collective ground states in single-layer NbSe2   pp92 - 97 Miguel M. Ugeda, Aaron J. Bradley, Yi Zhang, Seita Onishi, Yi Chen et al. doi:10.1038/nphys3527 What happens to correlated electronic phases - superconductivity and charge density wave ordering - as a material is thinned? Experiments show that both can remain intact in just a single layer of niobium diselenide. Transmission of torque at the nanoscale   pp98 - 103 Ian Williams, Erdal C. Oğuz, Thomas Speck, Paul Bartlett, Hartmut Löwen et al. doi:10.1038/nphys3490 A study of a composite soft-matter nanomechanical system consisting of a rotating ring of optically trapped colloidal particles confining a set of untrapped colloids demonstrates the possibility of gearwheel-like torque transmission on the nanoscale. Advertisement All content now open access including archives! Nature Communications is an open access journal that publishes high-quality research from all areas of the natural sciences. Papers published by the journal represent important advances of significance to specialists within each subject area including physics. Visit the website to explore ALL the content available within your field.    Measure for Measure Top Focus on Thermometry Rethinking the kelvin   p104 Michael de Podesta doi:10.1038/nphys3617 Michael de Podesta discusses the current definition of the kelvin - and why it is worth changing one last time. Top Natureevents is a fully searchable, multi-disciplinary database designed to maximise exposure for events organisers. The contents of the Natureevents Directory are now live. The digital version is available here. Find the latest scientific conferences, courses, meetings and symposia on natureevents.com. For event advertising opportunities across the Nature Publishing Group portfolio please contact natureevents@nature.com More Nature Events

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