Topologically protected refraction of robust kink states in valley photonic crystals Nat. Phys. (IF 22.806) Pub Date : 2017-11-13 Fei Gao, Haoran Xue, Zhaoju Yang, Kueifu Lai, Yang Yu, Xiao Lin, Yidong Chong, Gennady Shvets, Baile Zhang
Topologically protected refraction of robust kink states in valley photonic crystals Topologically protected refraction of robust kink states in valley photonic crystals, Published online: 13 November 2017; doi:10.1038/nphys4304 NatureArticleSnippet(type=short-summary, markup= A photonic crystal can realize an analogue of a valley Hall insulator, promising more flexibility than in condensed-matter systems to explore these exotic topological states. , isJats=true)
How drops start sliding over solid surfaces Nat. Phys. (IF 22.806) Pub Date : 2017-11-06 Nan Gao, Florian Geyer, Dominik W. Pilat, Sanghyuk Wooh, Doris Vollmer, Hans-Jürgen Butt, Rüdiger Berger
How drops start sliding over solid surfacesHow drops start sliding over solid surfaces, Published online: 06 November 2017; doi:10.1038/nphys4305NatureArticleSnippet(type=short-summary, markup=A liquid droplet is shown to slide across a solid surface subject to friction forces analogous with those between two solids. The phenomenon is generic, and closes a gap in our understanding of liquid–solid friction., isJats=true)
Phase ordering of charge density waves traced by ultrafast low-energy electron diffraction Nat. Phys. (IF 22.806) Pub Date : 2017-11-06 S. Vogelgesang, G. Storeck, J. G. Horstmann, T. Diekmann, M. Sivis, S. Schramm, K. Rossnagel, S. Schäfer, C. Ropers
Phase ordering of charge density waves traced by ultrafast low-energy electron diffractionPhase ordering of charge density waves traced by ultrafast low-energy electron diffraction, Published online: 06 November 2017; doi:10.1038/nphys4309NatureArticleSnippet(type=short-summary, markup=A tracing of the phase-ordering kinetics of a charge density wave system demonstrates the potential of ultrafast low-energy electron diffraction for studying phase transitions and ordering phenomena at surfaces and in low-dimensional systems., isJats=true)
Unconventional mass enhancement around the Dirac nodal loop in ZrSiS Nat. Phys. (IF 22.806) Pub Date : 2017-11-06 S. Pezzini, M. R. van Delft, L. M. Schoop, B. V. Lotsch, A. Carrington, M. I. Katsnelson, N. E. Hussey, S. Wiedmann
The topological properties of fermions arise from their low-energy Dirac-like band dispersion and associated chirality. Initially confined to points, extensions of the Dirac dispersion to lines, and even loops, have now been uncovered, and semimetals hosting such features have been identified. However, experimental evidence for the enhanced correlation effects predicted to occur in these topological semimetals has been lacking. Here, we report a quantum oscillation study of the nodal-loop semimetal ZrSiS in high magnetic fields that reveals significant enhancement in the effective mass of the quasiparticles residing near the nodal loop. Above a threshold field, magnetic breakdown occurs across gaps in the loop structure with orbits that enclose different windings around its vertices, each winding accompanied by an additional π Berry phase. The amplitudes of these breakdown orbits exhibit an anomalous temperature dependence. These findings demonstrate the emergence of novel, correlation-driven physics in ZrSiS associated with the Dirac-like quasiparticles.
Soft matter: Sticky fingers Nat. Phys. (IF 22.806) Pub Date : 2017-11-02 Federico Levi
Soft matter: Sticky fingersSoft matter: Sticky fingers, Published online: 02 November 2017; doi:10.1038/nphys4313
Many-body localization: Going long Nat. Phys. (IF 22.806) Pub Date : 2017-11-02 Andrea Taroni
Many-body localization: Going longMany-body localization: Going long, Published online: 02 November 2017; doi:10.1038/nphys4317
Ripples in spacetime Nat. Phys. (IF 22.806) Pub Date : 2017-11-02
Ripples in spacetimeRipples in spacetime, Published online: 02 November 2017; doi:10.1038/nphys4321NatureArticleSnippet(type=standfirst, markup=The 2017 Nobel prize in Physics has been awarded to Rainer Weiss, Barry C. Barish and Kip S. Thorne “for decisive contributions to the LIGO detector and the observation of gravitational waves”., isJats=true)
Quantum anomalous hall effect: Honeycomb recipe Nat. Phys. (IF 22.806) Pub Date : 2017-11-02 Luke Fleet
Quantum anomalous hall effect: Honeycomb recipeQuantum anomalous hall effect: Honeycomb recipe, Published online: 02 November 2017; doi:10.1038/nphys4319
Celebrate the scientific hierarchy Nat. Phys. (IF 22.806) Pub Date : 2017-11-02 George Ellis, David Sloan
Celebrate the scientific hierarchyCelebrate the scientific hierarchy, Published online: 02 November 2017; doi:10.1038/nphys4300NatureArticleSnippet(type=standfirst, markup=The validity of our scientific descriptions of reality does not hinge on their emergence from a more fundamental theory., isJats=true)
When lost in a multiverse Nat. Phys. (IF 22.806) Pub Date : 2017-11-02 Andre Geim
When lost in a multiverseWhen lost in a multiverse, Published online: 02 November 2017; doi:10.1038/nphys4310NatureArticleSnippet(type=standfirst, markup=Wonder material graphene makes metrology practical and relaxed, says Andre Geim., isJats=true)
Gas detection: Sensor extraordinaire Nat. Phys. (IF 22.806) Pub Date : 2017-11-02 Andreas H. Trabesinger
Gas detection: Sensor extraordinaireGas detection: Sensor extraordinaire, Published online: 02 November 2017; doi:10.1038/nphys4316
Biomechanics: Split sites Nat. Phys. (IF 22.806) Pub Date : 2017-11-01 Abigail Klopper
Biomechanics: Split sitesBiomechanics: Split sites, Published online: 02 November 2017; doi:10.1038/nphys4320
Quantum imaging with incoherently scattered light from a free-electron laser Nat. Phys. (IF 22.806) Pub Date : 2017-10-30 Raimund Schneider, Thomas Mehringer, Giuseppe Mercurio, Lukas Wenthaus, Anton Classen, Günter Brenner, Oleg Gorobtsov, Adrian Benz, Daniel Bhatti, Lars Bocklage, Birgit Fischer, Sergey Lazarev, Yuri Obukhov, Kai Schlage, Petr Skopintsev, Jochen Wagner, Felix Waldmann, Svenja Willing, Ivan Zaluzhnyy, Wilfried Wurth, Ivan A. Vartanyants, Ralf Röhlsberger, Joachim von Zanthier
Quantum imaging with incoherently scattered light from a free-electron laser Nature Physics, Published online: 30 October 2017; doi:10.1038/nphys4301 The intensity correlations in incoherently scattered X-rays from a free-electron laser can be exploited to image 2D objects with a resolution close to or below the diffraction limit.
Anomalous dispersion of microcavity trion-polaritons Nat. Phys. (IF 22.806) Pub Date : 2017-10-30 S. Dhara, C. Chakraborty, K. M. Goodfellow, L. Qiu, T. A. O’Loughlin, G. W. Wicks, Subhro Bhattacharjee, A. N. Vamivakas
Anomalous dispersion of microcavity trion-polaritons Nature Physics, Published online: 30 October 2017; doi:10.1038/nphys4303 A study of the strong coupling of different exciton species in two-dimensional molybdenum diselenide in a cavity uncovers the rich many-body physics and may lead to new devices.
The physics of quantum materials Nat. Phys. (IF 22.806) Pub Date : 2017-10-30 B. Keimer, J. E. Moore
The physical description of all materials is rooted in quantum mechanics, which describes how atoms bond and electrons interact at a fundamental level. Although these quantum effects can in many cases be approximated by a classical description at the macroscopic level, in recent years there has been growing interest in material systems where quantum effects remain manifest over a wider range of energy and length scales. Such quantum materials include superconductors, graphene, topological insulators, Weyl semimetals, quantum spin liquids, and spin ices. Many of them derive their properties from reduced dimensionality, in particular from confinement of electrons to two-dimensional sheets. Moreover, they tend to be materials in which electrons cannot be considered as independent particles but interact strongly and give rise to collective excitations known as quasiparticles. In all cases, however, quantum-mechanical effects fundamentally alter properties of the material. This Review surveys the electronic properties of quantum materials through the prism of the electron wavefunction, and examines how its entanglement and topology give rise to a rich variety of quantum states and phases; these are less classically describable than conventional ordered states also driven by quantum mechanics, such as ferromagnetism.
A scientist walks into a bar Nat. Phys. (IF 22.806) Pub Date : 2017-10-23 Nina Meinzer
A scientist walks into a bar Nature Physics, Published online: 23 October 2017; doi:10.1038/nphys4307
Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB6 Nat. Phys. (IF 22.806) Pub Date : 2017-10-23 M. Hartstein, W. H. Toews, Y.-T. Hsu, B. Zeng, X. Chen, M. Ciomaga Hatnean, Q. R. Zhang, S. Nakamura, A. S. Padgett, G. Rodway-Gant, J. Berk, M. K. Kingston, G. H. Zhang, M. K. Chan, S. Yamashita, T. Sakakibara, Y. Takano, J.-H. Park, L. Balicas, N. Harrison, N. Shitsevalova, G. Balakrishnan, G. G. Lonzarich, R. W. Hill, M. Sutherland, Suchitra E. Sebastian
Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB6 Nature Physics, Published online: 23 October 2017; doi:10.1038/nphys4295 Experimental study of the Kondo insulator SmB6 provides an alternative route to realize a Fermi surface in the absence of a conventional Fermi liquid.
Quantum gas microscopy of an attractive Fermi–Hubbard system Nat. Phys. (IF 22.806) Pub Date : 2017-10-23 Debayan Mitra, Peter T. Brown, Elmer Guardado-Sanchez, Stanimir S. Kondov, Trithep Devakul, David A. Huse, Peter Schauß, Waseem S. Bakr
Quantum gas microscopy of an attractive Fermi–Hubbard system Nature Physics, Published online: 23 October 2017; doi:10.1038/nphys4297 The simplest lattice model that allows the investigation of superconductivity with attractive interactions is realized using ultracold quantum gas. The experimental observation provides a lower bound on the strength of s-wave pairing correlations.
Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySe Nat. Phys. (IF 22.806) Pub Date : 2017-10-23 Zengyi Du, Xiong Yang, Dustin Altenfeld, Qiangqiang Gu, Huan Yang, Ilya Eremin, Peter J. Hirschfeld, Igor I. Mazin, Hai Lin, Xiyu Zhu, Hai-Hu Wen
Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySe Nature Physics, Published online: 23 October 2017; doi:10.1038/nphys4299 A scanning tunnelling microscopy study of an intercalated iron selenide-based superconductor reveals a sign change in its superconducting gap function, providing indirect evidence for the origin of the pairing mechanism in this system.
Curvature-induced defect unbinding and dynamics in active nematic toroids Nat. Phys. (IF 22.806) Pub Date : 2017-10-23 Perry W. Ellis, Daniel J. G. Pearce, Ya-Wen Chang, Guillermo Goldsztein, Luca Giomi, Alberto Fernandez-Nieves
Curvature-induced defect unbinding and dynamics in active nematic toroids Nature Physics, Published online: 23 October 2017; doi:10.1038/nphys4276 Topological defects in a turbulent active nematic on a toroidal surface are shown to segregate in regions of opposite curvature. Simulations suggest that this behaviour may be controlled — or even suppressed — by tuning the level of activity.
Experimentally probing topological order and its breakdown through modular matrices Nat. Phys. (IF 22.806) Pub Date : 2017-10-16 Zhihuang Luo, Jun Li, Zhaokai Li, Ling-Yan Hung, Yidun Wan, Xinhua Peng, Jiangfeng Du
Experimentally probing topological order and its breakdown through modular matrices Nature Physics, Published online: 16 October 2017; doi:10.1038/nphys4281 Fundamental fingerprints of topological orders may be characterized uniquely and purely by experimental means. Here the authors provide a proof of principle demonstration using interferometric measurement in a two-dimensional lattice system.
Symmetry breaking by quantum coherence in single electron attachment Nat. Phys. (IF 22.806) Pub Date : 2017-10-16 E. Krishnakumar, Vaibhav S. Prabhudesai, Nigel J. Mason
Symmetry breaking by quantum coherence in single electron attachment Nature Physics, Published online: 16 October 2017; doi:10.1038/nphys4289 Resonant electron attachment and subsequent dissociation of diatomic molecules is shown to exhibit spatial asymmetry as a consequence of coherent excitation and subsequent interference between reaction pathways.
Molecular physics: Breaking up is hard to do Nat. Phys. (IF 22.806) Pub Date : 2017-10-16 Daniel S. Slaughter, Thomas N. Rescigno
Molecular physics: Breaking up is hard to do Nature Physics, Published online: 16 October 2017; doi:10.1038/nphys4308 Dissociating hydrogen gas seems like it should be as easy as pulling apart two identical atoms. But resonant electron-impact experiments reveal that quantum interference induces a fundamental asymmetry in the process.
Nobel reactions Nat. Phys. (IF 22.806) Pub Date : 2017-10-04
The Nobel Prize, for all its shortcomings and imperfections, remains unmatched when it comes to the kind of emotions it generates.
Optomechanical nonreciprocity Nat. Phys. (IF 22.806) Pub Date : 2017-10-04 Ewold Verhagen, Andrea Alù
The two-way symmetry of electromagnetic wave propagation can be broken effectively in optomechanical systems, enabling new devices that route photons in unconventional ways.
Soft materials: A remedy for thinning hair Nat. Phys. (IF 22.806) Pub Date : 2017-08-21 Mitul Luhar
Vast beds of 'hair' coat many living systems, and usually exhibit shear-thinning behaviour — their flow resistance lessens with speed. But with geometric tweaks, such beds can also show shear-thickening and asymmetric ratchet-like behaviour.
Structural and quantum-state phase transition in van der Waals layered materials Nat. Phys. (IF 22.806) Pub Date : 2017-07-17 Heejun Yang, Sung Wng Kim, Manish Chhowalla, Young Hee Lee
With diverse polymorphisms and phase transitions that can be triggered using many methods, layered transition metal dichalcogenides are attractive materials for realizing novel topological states, as well as for a range of other applications.
Organic spintronics: Window of opportunity Nat. Phys. (IF 22.806) Pub Date : 2017-10-04 Christoph Boehme
A crystalline organic semiconductor that combines the long spin-relaxation times of organic semiconductors with the high charge-carrier mobilities typically found in inorganic semiconductors provides unprecedented prospects for organic spintronics.
Testing sub-gravitational forces on atoms from a miniature in-vacuum source mass Nat. Phys. (IF 22.806) Pub Date : 2017-07-03 Matt Jaffe, Philipp Haslinger, Victoria Xu, Paul Hamilton, Amol Upadhye, Benjamin Elder, Justin Khoury, Holger Müller
Atomic interferometry measurements of the gravitational force on free-falling atoms provide improved constraints on certain scalar field theories trying to explain dark energy.
Goldstone mode and pair-breaking excitations in atomic Fermi superfluids Nat. Phys. (IF 22.806) Pub Date : 2017-06-26 Sascha Hoinka, Paul Dyke, Marcus G. Lingham, Jami J. Kinnunen, Georg M. Bruun, Chris J. Vale
Bragg spectroscopy shows the evolution of gapless Goldstone modes and single-particle-like excitations in an atomic Fermi superfluid as it crosses from a Bardeen–Cooper–Schrieffer superfluid to the Bose–Einstein condensate regime.
Tracing the phase of focused broadband laser pulses Nat. Phys. (IF 22.806) Pub Date : 2017-07-10 Dominik Hoff, Michael Krüger, Lothar Maisenbacher, A. M. Sayler, Gerhard G. Paulus, Peter Hommelhoff
In different applications the Gouy phase is used to describe broadband lasers, but new 3D measurements of the spatial dependence of a focused laser pulse show serious deviations from the Gouy phase.
Dispersive charge density wave excitations in Bi2Sr2CaCu2O8+δ Nat. Phys. (IF 22.806) Pub Date : 2017-06-12 L. Chaix, G. Ghiringhelli, Y. Y. Peng, M. Hashimoto, B. Moritz, K. Kummer, N. B. Brookes, Y. He, S. Chen, S. Ishida, Y. Yoshida, H. Eisaki, M. Salluzzo, L. Braicovich, Z.-X. Shen, T. P. Devereaux, W.-S. Lee
Ultrahigh-resolution resonant inelastic X-ray scattering shows how dispersive charge density wave excitations influence the charge and lattice degrees of freedom in a high-Tc cuprate, pointing to a connection to the mysterious pseudogap state.
Stripes developed at the strong limit of nematicity in FeSe film Nat. Phys. (IF 22.806) Pub Date : 2017-07-17 Wei Li, Yan Zhang, Peng Deng, Zhilin Xu, S.-K. Mo, Ming Yi, Hao Ding, M. Hashimoto, R. G. Moore, D.-H. Lu, Xi Chen, Z.-X. Shen, Qi-Kun Xue
A hidden stripe-type charge ordering in multilayer iron selenide films on strontium titanate, resembling that in high-temperature cuprate superconductors, could help to explain the complex behaviour of this unusual iron-based superconductor.
4-spin plaquette singlet state in the Shastry–Sutherland compound SrCu2(BO3)2 Nat. Phys. (IF 22.806) Pub Date : 2017-07-17 M. E. Zayed, Ch. Rüegg, J. Larrea J., A. M. Läuchli, C. Panagopoulos, S. S. Saxena, M. Ellerby, D. F. McMorrow, Th. Strässle, S. Klotz, G. Hamel, R. A. Sadykov, V. Pomjakushin, M. Boehm, M. Jiménez–Ruiz, A. Schneidewind, E. Pomjakushina, M. Stingaciu, K. Conder, H. M. Rønnow
A detailed neutron scattering study of the Shastry–Sutherland material SrCu2(BO3)2 verifies the existence of a 4-spin plaquette singlet phase in this system.
Charge density wave quantum critical point with strong enhancement of superconductivity Nat. Phys. (IF 22.806) Pub Date : 2017-07-10 Thomas Gruner, Dongjin Jang, Zita Huesges, Raul Cardoso-Gil, Gerhard H. Fecher, Michael M. Koza, Oliver Stockert, Andrew P. Mackenzie, Manuel Brando, Christoph Geibel
An experimental study of the rare-earth intermetallic system LuPt2In reveals a strong enhancement of superconductivity near the charge density wave quantum critical point. This represents an unusual counter-example to cuprates, in which superconductivity and charge density waves tend to compete.
Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating Nat. Phys. (IF 22.806) Pub Date : 2017-06-19 Ye. O. Kazakov, J. Ongena, J. C. Wright, S. J. Wukitch, E. Lerche, M. J. Mantsinen, D. Van Eester, T. Craciunescu, V. G. Kiptily, Y. Lin, M. Nocente, F. Nabais, M. F. F. Nave, Y. Baranov, J. Bielecki, R. Bilato, V. Bobkov, K. Crombé, A. Czarnecka, J. M. Faustin, R. Felton, M. Fitzgerald, D. Gallart, L. Giacomelli, T. Golfinopoulos, A. E. Hubbard, Ph. Jacquet, T. Johnson, M. Lennholm, T. Loarer, M. Porkolab, S. E. Sharapov, D. Valcarcel, M. Van Schoor, H. Weisen
We describe a new technique for the efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed ‘three-ion’ scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of the method on the world-largest plasma magnetic confinement device, JET (Joint European Torus, Culham, UK), and the high-magnetic-field tokamak Alcator C-Mod (Cambridge, USA). The obtained results demonstrate efficient acceleration of 3He ions to high energies in dedicated hydrogen–deuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast 3He ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space-plasma environments, in particular, 3He-rich solar flares.
Magnetic-tunnelling-induced Weyl node annihilation in TaP Nat. Phys. (IF 22.806) Pub Date : 2017-07-10 Cheng-Long Zhang, Su-Yang Xu, C. M. Wang, Ziquan Lin, Z. Z. Du, Cheng Guo, Chi-Cheng Lee, Hong Lu, Yiyang Feng, Shin-Ming Huang, Guoqing Chang, Chuang-Han Hsu, Haiwen Liu, Hsin Lin, Liang Li, Chi Zhang, Jinglei Zhang, Xin-Cheng Xie, Titus Neupert, M. Zahid Hasan, Hai-Zhou Lu, Junfeng Wang, Shuang Jia
Weyl nodes are topological objects in three-dimensional metals. Whereas the energy of the lowest Landau band of a conventional Fermi pocket increases with magnetic field due to the zero-point energy (1/2ω), the lowest Landau band of Weyl cones stays at zero energy unless a strong magnetic field couples Weyl fermions of opposite chirality. In the Weyl semimetal TaP, which possesses two types of Weyl nodes (four pairs of W1 and eight pairs of W2 nodes), we observed such a magnetic coupling between the electron pockets arising from the W1 Weyl fermions. As a result, their lowest Landau bands move above the chemical potential, leading to a sharp sign reversal in the Hall resistivity at a specific magnetic field corresponding to the separation in momentum space of the W1 Weyl nodes, . By contrast, annihilation is not observed for the hole pocket because the separation of the W2 Weyl nodes is much larger. These findings reveal the nontrivial topology of Weyl fermions in high-field transport measurements and demonstrate the observation of Weyl node annihilation, which is a unique topological phenomenon associated with Weyl fermions.
Long-distance spin transport in a disordered magnetic insulator Nat. Phys. (IF 22.806) Pub Date : 2017-07-03 Devin Wesenberg, Tao Liu, Davor Balzar, Mingzhong Wu, Barry L. Zink
Spin transport through magnetic insulators via magnons has been explored for a variety of crystalline materials. Here we show dramatic effects of spin transport through an amorphous magnetic insulator, which is both magnetically and structurally disordered. We observe spin flow though amorphous yttrium-iron-garnet (a-YIG) thin films in a non-local geometry by use of the spin Hall and inverse spin Hall effects in platinum strips separated by ten or more micrometres. By comparing a-YIG grown on suspended micromachined thermal isolation platforms to the same film on bulk substrates, we show strong effects of in-plane thermal gradients on spin transport in the disordered film. The resulting signals are orders of magnitude larger than those seen in crystalline magnetic insulators, and easily measurable even for distances greater than 100 μm. In analogy to heat transport in glasses, where a range of vibrational excitations can allow large thermal conductivities, we suggest that efficient spin transport in disordered systems can occur via a similar spectrum of excitations that relies on strong local exchange interactions and does not require long-range order. This opens a new area for experimental and theoretical studies of spin transport, and sets a new direction in materials science for magnonic and spintronic devices.
Coexistence of ultra-long spin relaxation time and coherent charge transport in organic single-crystal semiconductors Nat. Phys. (IF 22.806) Pub Date : 2017-07-31 Junto Tsurumi, Hiroyuki Matsui, Takayoshi Kubo, Roger Häusermann, Chikahiko Mitsui, Toshihiro Okamoto, Shun Watanabe, Jun Takeya
Coherent charge transport can occur in organic semiconductor crystals thanks to the highly periodic electrostatic potential—despite the weak van der Waals bonds. And as spin–orbit coupling is usually weak in organic materials, robust spin transport is expected, which is essential if they are to be exploited for spintronic applications. In such systems, momentum relaxation occurs via scattering events, which enables an intrinsic mobility to be defined for band-like charge transport, which is >10 cm2 V−1 s−1. In contrast, there are relatively few experimental studies of the intrinsic spin relaxation for organic band-transport systems. Here, we demonstrate that the intrinsic spin relaxation in organic semiconductors is also caused by scattering events, with much less frequency than the momentum relaxation. Magnetotransport measurements and electron spin resonance spectroscopy consistently show a linear relationship between the two relaxation times over a wide temperature range, clearly manifesting the Elliott–Yafet type of spin relaxation mechanism. The coexistence of an ultra-long spin lifetime of milliseconds and the coherent band-like transport, resulting in a micrometre-scale spin diffusion length, constitutes a key step towards realizing spintronic devices based on organic single crystals.
Contact enhancement of locomotion in spreading cell colonies Nat. Phys. (IF 22.806) Pub Date : 2017-07-03 Joseph d’Alessandro, Alexandre P. Solon, Yoshinori Hayakawa, Christophe Anjard, François Detcheverry, Jean-Paul Rieu, Charlotte Rivière
The dispersal of cells from an initially constrained location is a crucial aspect of many physiological phenomena, ranging from morphogenesis to tumour spreading. In such processes, cell–cell interactions may deeply alter the motion of single cells, and in turn the collective dynamics. While contact phenomena like contact inhibition of locomotion are known to come into play at high densities, here we focus on the little explored case of non-cohesive cells at moderate densities. We fully characterize the spreading of micropatterned colonies of Dictyostelium discoideum cells from the complete set of individual trajectories. From data analysis and simulation of an elementary model, we demonstrate that contact interactions act to speed up the early population spreading by promoting individual cells to a state of higher persistence, which constitutes an as-yet unreported contact enhancement of locomotion. Our findings also suggest that the current modelling paradigm of memoryless active particles may need to be extended to account for the history-dependent internal state of motile cells.
Self-organization and positioning of bacterial protein clusters Nat. Phys. (IF 22.806) Pub Date : 2017-06-19 Seán M. Murray, Victor Sourjik
Many cellular processes require proteins to be precisely positioned within the cell. In some cases this can be attributed to passive mechanisms such as recruitment by other proteins in the cell or by exploiting the curvature of the membrane. However, in bacteria, active self-positioning is likely to play a role in multiple processes, including the positioning of the future site of cell division and cytoplasmic protein clusters. How can such dynamic clusters be formed and positioned? Here, we present a model for the self-organization and positioning of dynamic protein clusters into regularly repeating patterns based on a phase-locked Turing pattern. A single peak in the concentration is always positioned at the midpoint of the model cell, and two peaks are positioned at the midpoint of each half. Furthermore, domain growth results in peak splitting and pattern doubling. We argue that the model may explain the regular positioning of the highly conserved structural maintenance of chromosomes complexes on the bacterial nucleoid and that it provides an attractive mechanism for the self-positioning of dynamic protein clusters in other systems.
Nonlinear flow response of soft hair beds Nat. Phys. (IF 22.806) Pub Date : 2017-08-21 José Alvarado, Jean Comtet, Emmanuel de Langre, A. E. Hosoi
We are ‘hairy’ on the inside: beds of passive fibres anchored to a surface and immersed in fluids are prevalent in many biological systems, including intestines, tongues, and blood vessels. These hairs are soft enough to deform in response to stresses from fluid flows. Yet fluid stresses are in turn affected by hair deformation, leading to a coupled elastoviscous problem that is poorly understood. Here we investigate a biomimetic model system of elastomer hair beds subject to shear-driven Stokes flows. We characterize this system with a theoretical model that accounts for the large-deformation flow response of hair beds. Hair bending results in a drag-reducing nonlinearity because the hair tip lowers towards the base, widening the gap through which fluid flows. When hairs are cantilevered at an angle subnormal to the surface, flow against the grain bends hairs away from the base, narrowing the gap. The flow response of angled hair beds is axially asymmetric and amounts to a rectification nonlinearity. We identify an elastoviscous parameter that controls nonlinear behaviour. Our study raises the hypothesis that biological hairy surfaces function to reduce fluid drag. Furthermore, angled hairs may be incorporated in the design of integrated microfluidic components, such as diodes and pumps.
Oleoplaning droplets on lubricated surfaces Nat. Phys. (IF 22.806) Pub Date : 2017-06-26 Dan Daniel, Jaakko V. I. Timonen, Ruoping Li, Seneca J. Velling, Joanna Aizenberg
Recently, there has been much interest in using lubricated surfaces to achieve extreme liquid repellency: a foreign droplet immiscible with the underlying lubricant layer was shown to slide off at a small tilt angle <5°. This behaviour was hypothesized to arise from a thin lubricant overlayer film sandwiched between the droplet and solid substrate, but this has not been observed experimentally. Here, using thin-film interference, we are able to visualize the intercalated film under both static and dynamic conditions. We further demonstrate that for a moving droplet, the film thickness follows the Landau–Levich–Derjaguin law. The droplet is therefore oleoplaning—akin to tyres hydroplaning on a wet road—with minimal dissipative force and no contact line pinning. The techniques and insights presented in this study will inform future work on the fundamentals of wetting for lubricated surfaces and enable their rational design.
Insights through dimensions Nat. Phys. (IF 22.806) Pub Date : 2017-10-04 Tina Hecksher
Dimensional analysis is a powerful tool for assessing physical problems, reaffirms Tina Hecksher
The power of universal pictures Nat. Phys. (IF 22.806) Pub Date : 2017-09-05
The sky map presented by the Dark Energy Survey showcases the power of images to reach scientists and the wider public alike.
Physics students unite Nat. Phys. (IF 22.806) Pub Date : 2017-09-05
The International Conference of Physics Students continues its remarkable tradition.
Time to fix science prizes Nat. Phys. (IF 22.806) Pub Date : 2017-08-28 Shivaji Sondhi, Steven Kivelson
Science prizes should better reflect how modern science is carried out, argue Shivaji Sondhi and Steven Kivelson.
Exciton-polaritons: In full flow Nat. Phys. (IF 22.806) Pub Date : 2017-06-05 Thilo Stöferle
Flow without friction is a strange phenomenon usually seen in quantum fluids that are cooled to temperatures near absolute zero, but features of superfluidity have now been seen with polaritons at ambient conditions.
Heavy ion collisions: A clash of photons Nat. Phys. (IF 22.806) Pub Date : 2017-08-14 Spencer R. Klein
The ATLAS Collaboration observed photons elastically scattering from other photons — an effect predicted by quantum electrodynamics over 80 years ago.
Rotational superradiant scattering in a vortex flow Nat. Phys. (IF 22.806) Pub Date : 2017-06-12 Theo Torres, Sam Patrick, Antonin Coutant, Maurício Richartz, Edmund W. Tedford, Silke Weinfurtner
The amplification of waves reflected from a rotating obstacle, or superradiance, has been predicted in hydrodynamics and black-hole physics. An experiment with rotating vortex flows confirms this phenomenon.
Spin conversion on the nanoscale Nat. Phys. (IF 22.806) Pub Date : 2017-07-10 YoshiChika Otani, Masashi Shiraishi, Akira Oiwa, Eiji Saitoh, Shuichi Murakami
Spins can act as mediators to interconvert electricity, light, sound, vibration and heat. This Progress article gives an overview of the recent advances associated with nanoscale spin conversion.
Room-temperature superfluidity in a polariton condensate Nat. Phys. (IF 22.806) Pub Date : 2017-06-05 Giovanni Lerario, Antonio Fieramosca, Fábio Barachati, Dario Ballarini, Konstantinos S. Daskalakis, Lorenzo Dominici, Milena De Giorgi, Stefan A. Maier, Giuseppe Gigli, Stéphane Kéna-Cohen, Daniele Sanvitto
Superfluidity is a phenomenon usually restricted to cryogenic temperatures, but organic microcavities provide the conditions for a superfluid flow of polaritons at room temperature.
Direct optical detection of Weyl fermion chirality in a topological semimetal Nat. Phys. (IF 22.806) Pub Date : 2017-05-29 Qiong Ma, Su-Yang Xu, Ching-Kit Chan, Cheng-Long Zhang, Guoqing Chang, Yuxuan Lin, Weiwei Xie, Tomás Palacios, Hsin Lin, Shuang Jia, Patrick A. Lee, Pablo Jarillo-Herrero, Nuh Gedik
Measuring the photocurrent response to circularly polarized mid-infrared light provides direct access to the chirality of Weyl fermions in Weyl semimetals — the property responsible for a range of exotic phenomena.
Numerical test of the Edwards conjecture shows that all packings are equally probable at jamming Nat. Phys. (IF 22.806) Pub Date : 2017-06-26 Stefano Martiniani, K. Julian Schrenk, Kabir Ramola, Bulbul Chakraborty, Daan Frenkel
A decades-old proposal that all distinct packings are equally probable in granular media has gone unproven due to the sheer number of packings involved. Numerical simulation now demonstrates that it holds — precisely at the jamming threshold.
Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC Nat. Phys. (IF 22.806) Pub Date : 2017-08-14 ATLAS Collaboration
Light-by-light scattering (γγ γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb−1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 ± 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (γγ) Pb(∗) + Pb(∗)γγ, for photon transverse energy ET > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ± 17 (syst.) nb, which is in agreement with the standard model predictions.
Spectroscopic evidence of a new energy scale for superconductivity in H3S Nat. Phys. (IF 22.806) Pub Date : 2017-06-19 F. Capitani, B. Langerome, J.-B. Brubach, P. Roy, A. Drozdov, M. I. Eremets, E. J. Nicol, J. P. Carbotte, T. Timusk
The discovery of a superconducting phase in sulfur hydride under high pressure with a critical temperature above 200 K has provided fresh impetus to the search for superconductors at ever higher temperatures. Although this system displays all of the hallmarks of superconductivity, the mechanism through which it arises remains to be determined. Here we provide a first optical spectroscopy study of this superconductor. Experimental results for the optical reflectivity of H3S, under hydrostatic pressure of 150 GPa, for several temperatures and over the range 60 to 600 meV of photon energies, are compared with theoretical calculations based on Eliashberg theory. Two significant features stand out: some remarkably strong infrared-active phonons at around 160 meV, and a band with a depressed reflectance in the superconducting state in the region from 450 meV to 600 meV. In this energy range H3S becomes more reflecting with increasing temperature, a change that is traced to superconductivity originating from the electron–phonon interaction. The shape, magnitude and energy dependence of this band at 150 K agrees with our calculations. This provides strong evidence of a conventional mechanism. However, the unusually strong optical phonon suggests a contribution of electronic degrees of freedom.
Large orbital polarization in a metallic square-planar nickelate Nat. Phys. (IF 22.806) Pub Date : 2017-06-12 Junjie Zhang, A. S. Botana, J. W. Freeland, D. Phelan, Hong Zheng, V. Pardo, M. R. Norman, J. F. Mitchell
High-temperature cuprate superconductivity remains a defining problem in condensed-matter physics. Among myriad approaches to addressing this problem has been the study of alternative transition metal oxides with similar structures and 3d electron count that are suggested as proxies for cuprate physics. None of these analogues has been superconducting, and few are even metallic. Here, we report that the low-valent, quasi-two-dimensional trilayer compound Pr4Ni3O8 avoids a charge-stripe-ordered phase previously reported for La4Ni3O8, leading to a metallic ground state. X-ray absorption spectroscopy shows that metallic Pr4Ni3O8 exhibits a low-spin configuration with significant orbital polarization and pronounced dx2−y2 character in the unoccupied states above the Fermi energy, a hallmark of the cuprate superconductors. Density functional theory calculations corroborate this finding, and reveal that the dx2−y2 orbital dominates the near-Ef occupied states as well. Belonging to a regime of 3d electron count found for hole-doped cuprates, Pr4Ni3O8 thus represents one of the closest analogues to cuprates yet reported and a singularly promising candidate for high-Tc superconductivity if electron doping could be achieved.
Direct measurement of polariton–polariton interaction strength Nat. Phys. (IF 22.806) Pub Date : 2017-06-05 Yongbao Sun, Yoseob Yoon, Mark Steger, Gangqiang Liu, Loren N. Pfeiffer, Ken West, David W. Snoke, Keith A. Nelson
Exciton–polaritons in a microcavity are composite two-dimensional bosonic quasiparticles, arising from the strong coupling between confined light modes in a resonant planar optical cavity and excitonic transitions. Quantum phenomena such as Bose–Einstein condensation, superfluidity, quantized vortices, and macroscopic quantum states have been realized at temperatures from tens of kelvin up to room temperatures. Crucially, many of these effects of exciton–polaritons depend on the polariton–polariton interaction strength. Despite the importance of this parameter, it has been difficult to make an accurate experimental measurement, mostly because of the difficulty in determining the absolute densities of polaritons and bare excitons. Here we report a direct measurement of the polariton–polariton interaction strength in a very high-Q microcavity structure. By allowing polaritons to propagate over 20 μm to the centre of a laser-generated annular trap, we are able to separate the polariton–polariton interactions from polariton–exciton interactions. The interaction strength is deduced from the energy renormalization of the polariton dispersion as the polariton density is increased, using the polariton condensation as a benchmark for the density. We find that the interaction strength is about two orders of magnitude larger than previous theoretical estimates, putting polaritons in the strongly interacting regime.
Microwave spectroscopy of spinful Andreev bound states in ballistic semiconductor Josephson junctions Nat. Phys. (IF 22.806) Pub Date : 2017-06-05 David J. van Woerkom, Alex Proutski, Bernard van Heck, Daniël Bouman, Jukka I. Väyrynen, Leonid I. Glazman, Peter Krogstrup, Jesper Nygård, Leo P. Kouwenhoven, Attila Geresdi
The superconducting proximity effect in semiconductor nanowires has recently enabled the study of new superconducting architectures, such as gate-tunable superconducting qubits and multiterminal Josephson junctions. As opposed to their metallic counterparts, the electron density in semiconductor nanosystems is tunable by external electrostatic gates, providing a highly scalable and in situ variation of the device properties. In addition, semiconductors with large g-factor and spin–orbit coupling have been shown to give rise to exotic phenomena in superconductivity, such as φ0 Josephson junctions and the emergence of Majorana bound states. Here, we report microwave spectroscopy measurements that directly reveal the presence of Andreev bound states (ABS) in ballistic semiconductor channels. We show that the measured ABS spectra are the result of transport channels with gate-tunable, high transmission probabilities up to 0.9, which is required for gate-tunable Andreev qubits and beneficial for braiding schemes of Majorana states. For the first time, we detect excitations of a spin-split pair of ABS and observe symmetry-broken ABS, a direct consequence of the spin–orbit coupling in the semiconductor.
Controlled release of multiphoton quantum states from a microwave cavity memory Nat. Phys. (IF 22.806) Pub Date : 2017-06-05 Wolfgang Pfaff, Christopher J. Axline, Luke D. Burkhart, Uri Vool, Philip Reinhold, Luigi Frunzio, Liang Jiang, Michel H. Devoret, Robert J. Schoelkopf
Signal transmission loss in a quantum network can be overcome by encoding quantum states in complex multiphoton fields. But transmitting quantum information encoded in this way requires that locally stored states can be converted to propagating fields. Here we experimentally show the controlled conversion of multiphoton quantum states, such as Schrödinger cat states, from a microwave cavity quantum memory into propagating modes. By parametric conversion using the nonlinearity of a single Josephson junction, we can release the cavity state in ~500 ns, about three orders of magnitude faster than its intrinsic lifetime. This mechanism—which we dub Schrödinger’s catapult—faithfully converts arbitrary cavity fields to travelling signals with an estimated efficiency of >90%, enabling the on-demand generation of complex itinerant quantum states. Importantly, the release process can be precisely controlled on fast timescales, allowing us to generate entanglement between the cavity and the travelling mode by partial conversion.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
- Acad. Manag. Ann.
- Acc. Chem. Res.
- ACS Appl. Mater. Interfaces
- ACS Biomater. Sci. Eng.
- ACS Catal.
- ACS Cent. Sci.
- ACS Chem. Biol.
- ACS Chem. Neurosci.
- ACS Comb. Sci.
- ACS Earth Space Chem.
- ACS Energy Lett.
- ACS Infect. Dis.
- ACS Macro Lett.
- ACS Med. Chem. Lett.
- ACS Nano
- ACS Omega
- ACS Photonics
- ACS Sens.
- ACS Sustainable Chem. Eng.
- ACS Synth. Biol.
- Acta Mater.
- Acta Neuropathol.
- Adv. Drug Deliver. Rev.
- Adv. Electron. Mater.
- Adv. Energy Mater.
- Adv. Funct. Mater.
- Adv. Healthcare Mater.
- Adv. Mater.
- Adv. Opt. Mater.
- Adv. Opt. Photon.
- Adv. Phys.
- Adv. Sci.
- Adv. Synth. Catal.
- AlChE J.
- Alzheimers Dement.
- Am. J. Hum. Genet.
- Am. J. Psychiatry
- Am. J. Respir. Crit. Care Med.
- Anal. Chem.
- Anal. Chim. Acta
- Anal. Methods
- Angew. Chem. Int. Ed.
- Ann. Intern. Med.
- Ann. Neurol.
- Ann. Oncol.
- Ann. Rheum. Dis.
- Annu. Rev. Anal. Chem.
- Annu. Rev. Astron. Astrophys.
- Annu. Rev. Biochem.
- Annu. Rev. Biomed. Eng.
- Annu. Rev. Biophys.
- Annu. Rev. Cell Dev. Biol.
- Annu. Rev. Clin. Psychol.
- Annu. Rev. Condens. Matter Phys.
- Annu. Rev. Earth Planet. Sci.
- Annu. Rev. Ecol. Evol. Syst.
- Annu. Rev. Entomol.
- Annu. Rev. Fluid Mech.
- Annu. Rev. Immunol.
- Annu. Rev. Mar. Sci.
- Annu. Rev. Mater. Res.
- Annu. Rev. Med.
- Annu. Rev. Microbiol.
- Annu. Rev. Neurosci.
- Annu. Rev. Nutr.
- Annu. Rev. Pathol. Mech. Dis.
- Annu. Rev. Pharmacol. Toxicol.
- Annu. Rev. Phys. Chem.
- Annu. Rev. Physiol.
- Annu. Rev. Phytopathol.
- Annu. Rev. Plant Biol.
- Annu. Rev. Psychol.
- Annu. Rev. Publ. Health
- Annu. Rev. Virol.
- Antivir. Res.
- Appl. Catal. A Gen.
- Appl. Catal. B Environ.
- Appl. Energy
- Appl. Phys. Lett.
- Appl. Phys. Rev.
- Arch. Pharm.
- Asian J. Org. Chem.
- CA: Cancer J. Clin.
- Cancer Cell
- Cancer Discov.
- Cancer Res.
- Carbohydr. Polym.
- Catal. Sci. Technol.
- Catal. Today
- Cell Chem. Bio.
- Cell Host Microbe
- Cell Metab.
- Cell Res.
- Cell Stem Cell
- Ceram. Int.
- Chem. Asian J.
- Chem. Bio. Drug Des.
- Chem. Commun.
- Chem. Educ. Res. Pract.
- Chem. Eng. J.
- Chem. Eur. J.
- Chem. Mater.
- Chem. Phys.
- Chem. Phys. Lett.
- Chem. Res. Toxicol.
- Chem. Rev.
- Chem. Sci.
- Chem. Soc. Rev.
- Circ. Res.
- Clin. Cancer Res.
- Clin. Microbiol. Rev.
- Compos. Part A Appl. Sci. Manuf.
- Comput. Fluids
- Coordin. Chem. Rev.
- Corros. Sci.
- Crit. Rev. Food Sci. Nutr.
- Cryst. Growth Des.
- Curr. Opin. Biotech.
- Curr. Opin. Cell Biol.
- Ecol. Lett.
- Electrochem. Commun.
- Electrochim. Acta
- Endocr. Rev.
- Energy Environ. Sci.
- Energy Fuels
- Environ. Pollut.
- Environ. Sci. Technol.
- Environ. Sci. Technol. Lett.
- Environ. Sci.: Nano
- Environ. Sci.: Processes Impacts
- Environ. Sci.: Water Res. Technol.
- Eur. Heart J.
- Eur. J. Inorg. Chem.
- Eur. J. Med. Chem.
- Eur. J. Org. Chem.
- Eur. Polym. J.
- Eur. Respir. J.
- Eur. Urol.
- J Nucl. Med.
- J. Agric. Food Chem.
- J. Allergy Clin. Immunol.
- J. Alloys Compd.
- J. Am. Ceram. Soc.
- J. Am. Chem. Soc.
- J. Am. Coll. Cardiol.
- J. Anal. At. Spectrom.
- J. Antibiot.
- J. Cachexia Sarcopenia Muscle
- J. Catal.
- J. Chem. Educ.
- J. Chem. Eng. Data
- J. Chem. Inf. Model.
- J. Chem. Phys.
- J. Chem. Theory Comput.
- J. Chromatogr. A
- J. Chromatogr. B
- J. Clin. Invest.
- J. Clin. Oncol.
- J. Comput. Chem.
- J. Comput. Phys.
- J. Control. Release
- J. Cryst. Growth
- J. Electrochem. Soc.
- J. Eur. Ceram. Soc.
- J. Exp. Med.
- J. Fluid Mech.
- J. Fluorine Chem.
- J. Funct. Foods
- J. Hazard. Mater.
- J. Hepatol.
- J. Mater. Chem. A
- J. Mater. Chem. B
- J. Mater. Chem. C
- J. Med. Chem.
- J. Membr. Sci.
- J. Nat. Gas Sci. Eng.
- J. Nat. Prod.
- J. Natl. Cancer Inst.
- J. Org. Chem.
- J. Photochem. Photobiol. C Photochem. Rev.
- J. Phys. Chem. A
- J. Phys. Chem. B
- J. Phys. Chem. C
- J. Phys. Chem. Lett.
- J. Pineal. Res.
- J. Power Sources
- J. Proteome Res.
- J. Virol.
- JACC Cardiovasc. Imag.
- JAMA Intern. Med.
- JAMA Neurol.
- JAMA Oncol.
- JAMA Pediatr.
- JAMA Psychiatry
- Macromol. Rapid Commun.
- Mass Spectrom. Rev.
- Mater. Chem. Front.
- Mater. Des.
- Mater. Horiz.
- Mater. Sci. Eng. A
- Mater. Sci. Eng. R Rep.
- Mater. Today
- Meat Sci.
- Med. Chem. Commun.
- Med. Res. Rev.
- Microbiol. Mol. Biol. Rev.
- Microchim. Acta
- Mol. Biosyst.
- Mol. Cancer Ther.
- Mol. Catal.
- Mol. Cell
- Mol. Pharmaceutics
- Mol. Psychiatry
- Mol. Syst. Des. Eng.
- N. Engl. J. Med.
- Nano Energy
- Nano Lett.
- Nano Res.
- Nano Today
- Nano-Micro Lett.
- Nanoscale Horiz.
- Nat. Biomed. Eng.
- Nat. Biotechnol.
- Nat. Cell. Biol.
- Nat. Chem.
- Nat. Chem. Biol.
- Nat. Clim. Change
- Nat. Commun.
- Nat. Energy
- Nat. Genet.
- Nat. Geosci.
- Nat. Immunol.
- Nat. Mater.
- Nat. Med.
- Nat. Methods
- Nat. Microbiol.
- Nat. Nanotech.
- Nat. Neurosci.
- Nat. Photon.
- Nat. Phys.
- Nat. Plants
- Nat. Prod. Rep.
- Nat. Protoc.
- Nat. Rev. Cancer
- Nat. Rev. Cardiol.
- Nat. Rev. Chem.
- Nat. Rev. Clin. Oncol.
- Nat. Rev. Drug. Disc.
- Nat. Rev. Endocrinol.
- Nat. Rev. Gastroenterol. Hepatol.
- Nat. Rev. Genet.
- Nat. Rev. Immunol.
- Nat. Rev. Mater.
- Nat. Rev. Microbiol.
- Nat. Rev. Mol. Cell Biol.
- Nat. Rev. Nephrol.
- Nat. Rev. Neurol.
- Nat. Rev. Neurosci.
- Nat. Rev. Rheumatol.
- Nat. Struct. Mol. Biol.
- New J. Chem.
- NPG Asia Mater.
- Nucleic Acids Res.