Something to look forward to - p369

doi:10.1038/nphys1287

It's tempting to look back, but there's so much more to come.

Full Text - Something to look forward to | PDF (123 KB) - Something to look forward to

What did you do? - p369

doi:10.1038/nphys1305

Nature Physics now requires a statement of authors' contributions to a paper.

Full Text - What did you do? | PDF (123 KB) - What did you do?

Fusion–fission hybrids revisited - pp370 - 372

Jeffrey P. Freidberg & Andrew C. Kadak

doi:10.1038/nphys1288

With the increasingly urgent need to find solutions to the impending energy crisis, there is growing interest within the fusion community in revisiting the concept of the fusion–fission hybrid reactor. But how soon could such reactors be realized, and could they meet the challenges of the coming century?

Full Text - Fusion–fission hybrids revisited | PDF (526 KB) - Fusion–fission hybrids revisited

Attack of the cyberspider - p373

Mark Buchanan

doi:10.1038/nphys1289

Full Text - Attack of the cyberspider | PDF (87 KB) - Attack of the cyberspider

Film: Isn't it demonic - pp374 - 375

doi:10.1038/nphys1290

Full Text - FilmIsn't it demonic | PDF (280 KB) - FilmIsn't it demonic

Film: Boldly going...where? - p375

doi:10.1038/nphys1291

Full Text - FilmBoldly going...where? | PDF (145 KB) - FilmBoldly going...where?

Our choice from the recent literature - p376

doi:10.1038/nphys1292

Full Text - Our choice from the recent literature | PDF (138 KB) - Our choice from the recent literature

Biophysics: Cells guided on their journey - pp377 - 378

Benoit Ladoux

doi:10.1038/nphys1281

The formation of complex organs, tissue repair and metastasis all require a coordinated regulation of the shape and movement of groups of cells. The mechanical means of communication between cells is crucial to understanding collective cell motions — so how can cells transmit physical forces within cell sheets?

Full Text - BiophysicsCells guided on their journey | PDF (128 KB) - BiophysicsCells guided on their journey

Subject Category: Biological physics

See also: Letter by Trepat et al.

Topological insulators: The next generation - pp378 - 380

Joel Moore

doi:10.1038/nphys1294

Spin–orbit coupling in some materials leads to the formation of surface states that are topologically protected from scattering. Theory and experiments have found an important new family of such materials.

Full Text - Topological insulatorsThe next generation | PDF (500 KB) - Topological insulatorsThe next generation

Subject Categories: Condensed-matter physics | Materials physics

See also: Letter by Xia et al. | Article by Zhang et al.

Nuclear physics: An afternoon's outing - p380

Alison Wright

doi:10.1038/nphys1280

Full Text - Nuclear physicsAn afternoon's outing | PDF (384 KB) - Nuclear physicsAn afternoon's outing

Subject Categories: Atomic and molecular physics | Nuclear physics

Quantum phase transitions: Entanglement stirred up - p381

Jacob A. Dunningham

doi:10.1038/nphys1295

Stirring a two-dimensional quantum fluid at just the right frequency causes the particles to develop strong quantum correlations. This could reveal much about the nature of phase transitions.

Full Text - Quantum phase transitionsEntanglement stirred up | PDF (97 KB) - Quantum phase transitionsEntanglement stirred up

Subject Categories: Quantum physics | Statistical physics, thermodynamics and nonlinear dynamics

See also: Article by Dagnino et al.

Millihertz-linewidth lasers: A sharper laser - pp382 - 383

Uwe Sterr & Christian Lisdat

doi:10.1038/nphys1296

A new approach to lasers that promises optical emission with a spectral linewidth of just 1 mHz could lead to even more accurate and stable atomic clocks.

Full Text - Millihertz-linewidth lasersA sharper laser | PDF (180 KB) - Millihertz-linewidth lasersA sharper laser

Subject Categories: Atomic and molecular physics | Optical physics

History of quantum theory: The short version - p383

Andreas Trabesinger

doi:10.1038/nphys1279

Full Text - History of quantum theoryThe short version | PDF (117 KB) - History of quantum theoryThe short version

Subject Category: Quantum physics

Superconductor-metal heterostructures: Coherent conductors at a distance - pp384 - 385

Matthias Eschrig

doi:10.1038/nphys1293

A demonstration that Cooper pairs mediate a non-local coherent coupling between carriers in two normal metal electrodes connected to a superconductor could lead to novel types of superconducting quantum interference devices for studying cross-correlations.

Full Text - Superconductor-metal heterostructuresCoherent conductors at a distance | PDF (140 KB) - Superconductor-metal heterostructuresCoherent conductors at a distance

Subject Categories: Condensed-matter physics | Electronics, photonics and device physics

See also: Letter by Cadden-Zimansky et al.

Quantum gravity: Progress at a price - pp385 - 386

Matt Visser

doi:10.1038/nphys1298

The publication of a potentially testable quantum field theory that can accommodate gravity is causing excitement — but it comes at the expense of Lorentz invariance.

Full Text - Quantum gravityProgress at a price | PDF (126 KB) - Quantum gravityProgress at a price

Subject Category: Particle physics

Iron arsenide superconductors: What is the glue? - pp386 - 387

D. G. Hinks

doi:10.1038/nphys1297

Is superconductivity in the iron arsenides conventional? The large isotope effect on both the magnetic and superconducting transitions may indicate that magnetic fluctuations are involved in the superconducting pairing.

Full Text - Iron arsenide superconductorsWhat is the glue? | PDF (138 KB) - Iron arsenide superconductorsWhat is the glue?

Subject Categories: Condensed-matter physics | Materials physics

High-fidelity transmission of entanglement over a high-loss free-space channel - pp389 - 392

Alessandro Fedrizzi, Rupert Ursin, Thomas Herbst, Matteo Nespoli, Robert Prevedel, Thomas Scheidl, Felix Tiefenbacher, Thomas Jennewein & Anton Zeilinger

doi:10.1038/nphys1255

An experiment distributing entangled photons over 144 km significantly raises the bar on distance, channel loss and transmission time—encouraging news with regard to future long-distance quantum-communication networks.

First Paragraph - High-fidelity transmission of entanglement over a high-loss free-space channel | Full Text - High-fidelity transmission of entanglement over a high-loss free-space channel | PDF (846 KB) - High-fidelity transmission of entanglement over a high-loss free-space channel

Subject Categories: Quantum physics | Techniques and instrumentation | Information theory and computation

Cooper-pair-mediated coherence between two normal metals - pp393 - 397

P. Cadden-Zimansky, J. Wei & V. Chandrasekhar

doi:10.1038/nphys1252

The separation between two electrons bound in a Cooper pair in a conventional superconductor can extend up to several hundred nanometres. A new study shows that these long-range interactions can reach beyond the confines of a superconductor itself to coherently couple electrons in two normal metals either side of the superconductor.

First Paragraph - Cooper-pair-mediated coherence between two normal metals | Full Text - Cooper-pair-mediated coherence between two normal metals | PDF (1,198 KB) - Cooper-pair-mediated coherence between two normal metals | Supplementary information

Subject Categories: Condensed-matter physics | Electronics, photonics and device physics

See also: News and Views by Eschrig

Observation of a large-gap topological-insulator class with a single Dirac cone on the surface - pp398 - 402

Y. Xia, D. Qian, D. Hsieh, L. Wray, A. Pal, H. Lin, A. Bansil, D. Grauer, Y. S. Hor, R. J. Cava & M. Z. Hasan

doi:10.1038/nphys1274

Topological insulators are exotic states of matter that show quantum-Hall-like behaviour in the absence of a magnetic field. Surface states in such systems are protected against scattering and are thought to provide an avenue for the realization of fault-tolerant quantum computing. Experiments now reveal the observation of such a topological state of matter in Bi₂Se₃, a naturally occurring stoichiometric material with a simple surface-state structure and a bulk energy gap larger than k_BT at room temperature.

First Paragraph - Observation of a large-gap topological-insulator class with a single Dirac cone on the surface | Full Text - Observation of a large-gap topological-insulator class with a single Dirac cone on the surface | PDF (951 KB) - Observation of a large-gap topological-insulator class with a single Dirac cone on the surface | Supplementary information

Subject Categories: Condensed-matter physics | Materials physics

See also: News and Views by Moore

Collective excitations of composite fermions across multiple levels - pp403 - 406

Dwipesh Majumder, Sudhansu S. Mandal & Jainendra K. Jain

doi:10.1038/nphys1275

A recent experimental study of the fractional quantum Hall state—a prototypical system exhibiting strong collective quantum behaviour—provided evidence for the existence of unexpected collective modes at a filling factor of 1/3. Fully microscopic calculations now explain these modes as arising from collective excitations within the composite fermion theory.

First Paragraph - Collective excitations of composite fermions across multiple : [Lambda]: levels | Full Text - Collective excitations of composite fermions across multiple levels | PDF (530 KB) - Collective excitations of composite fermions across multiple levels | Supplementary information

Subject Categories: Condensed-matter physics | Materials physics

Breakdown of the nuclear-spin-temperature approach in quantum-dot demagnetization experiments - pp407 - 411

P. Maletinsky, M. Kroner & A. Imamoglu

doi:10.1038/nphys1273

Interacting nuclear spins on a crystalline lattice are commonly believed to be well described within a thermodynamic framework that uses the concept of spin temperature. Demagnetization experiments now challenge this belief, showing that in general the spin-temperature concept fails to describe a nuclear-spin ensemble in a quantum dot when strong quadrupolar interactions are induced by strain.

First Paragraph - Breakdown of the nuclear-spin-temperature approach in quantum-dot demagnetization experiments | Full Text - Breakdown of the nuclear-spin-temperature approach in quantum-dot demagnetization experiments | PDF (629 KB) - Breakdown of the nuclear-spin-temperature approach in quantum-dot demagnetization experiments

Subject Categories: Nanotechnology | Condensed-matter physics

Atomic wavefunctions probed through strong-field light–matter interaction - pp412 - 416

D. Shafir, Y. Mairesse, D. M. Villeneuve, P. B. Corkum & N. Dudovich

doi:10.1038/nphys1251

A method for tomographic imaging of molecular orbitals—based on the alignment of molecules in the laboratory frame and linearly polarized laser fields—has now been extended to atoms, which cannot be naturally aligned.

First Paragraph - Atomic wavefunctions probed through strong-field light-matter interaction | Full Text - Atomic wavefunctions probed through strong-field light–matter interaction | PDF (662 KB) - Atomic wavefunctions probed through strong-field light–matter interaction

Subject Categories: Optical physics | Atomic and molecular physics

Signatures of universal four-body phenomena and their relation to the Efimov effect - pp417 - 421

J. von Stecher, J. P. D'Incao & Chris H. Greene

doi:10.1038/nphys1253

A theoretical study predicts universal signatures of four-body physics in cold-gas experiments, and presents evidence that these have already been observed.

First Paragraph - Signatures of universal four-body phenomena and their relation to the Efimov effect | Full Text - Signatures of universal four-body phenomena and their relation to the Efimov effect | PDF (1,099 KB) - Signatures of universal four-body phenomena and their relation to the Efimov effect | Supplementary information

Subject Category: Atomic and molecular physics

A unified explanation of the Kadowaki–Woods ratio in strongly correlated metals - pp422 - 425

A. C. Jacko, J. O. Fjærestad & B. J. Powell

doi:10.1038/nphys1249

The Kadowaki–Woods ratio attempts to relate the temperature dependence of a metal to its heat capacity. However, as it takes different values for different classes of metals it is not universal. By including effects related to carrier density and spatial dimensionality, a much more universal ratio, which describes the properties of many different systems, has been achieved.

First Paragraph - A unified explanation of the Kadowaki-Woods ratio in strongly correlated metals | Full Text - A unified explanation of the Kadowaki–Woods ratio in strongly correlated metals | PDF (572 KB) - A unified explanation of the Kadowaki–Woods ratio in strongly correlated metals | Supplementary information

Subject Category: Condensed-matter physics

Physical forces during collective cell migration - pp426 - 430

Xavier Trepat, Michael R. Wasserman, Thomas E. Angelini, Emil Millet, David A. Weitz, James P. Butler & Jeffrey J. Fredberg

doi:10.1038/nphys1269

It has been thought that sheets of cells move by traction forces exerted by the cells at the leading edge of the sheet. Using traction microscopy to create a map of physical forces, it is now shown that in fact it is cells many rows from the front that do most of the work.

First Paragraph - Physical forces during collective cell migration | Full Text - Physical forces during collective cell migration | PDF (1,374 KB) - Physical forces during collective cell migration | Supplementary information

Subject Category: Biological physics

See also: News and Views by Ladoux

Vortex nucleation as a case study of symmetry breaking in quantum systems - pp431 - 437

D. Dagnino, N. Barberán, M. Lewenstein & J. Dalibard

doi:10.1038/nphys1277

A potentially general mechanism for symmetry breaking in mesoscopic quantum systems is revealed in a theoretical study, which shows how, in a rotating Bose–Einstein condensate, the symmetry properties of the true many-body state are related to those of its mean-field approximation.

Abstract - Vortex nucleation as a case study of symmetry breaking in quantum systems | Full Text - Vortex nucleation as a case study of symmetry breaking in quantum systems | PDF (998 KB) - Vortex nucleation as a case study of symmetry breaking in quantum systems

Subject Categories: Quantum physics | Statistical physics, thermodynamics and nonlinear dynamics

See also: News and Views by Dunningham

Topological insulators in Bi₂Se₃, Bi₂Te₃ and Sb₂Te₃ with a single Dirac cone on the surface - pp438 - 442

Haijun Zhang, Chao-Xing Liu, Xiao-Liang Qi, Xi Dai, Zhong Fang & Shou-Cheng Zhang

doi:10.1038/nphys1270

First-principles calculations predict that Bi₂Se₃, Bi₂Te₃ and Sb₂Te₃ are topological insulators—three-dimensional semiconductors with unusual surface states generated by spin–orbit coupling—whose surface states are described by a single gapless Dirac cone. The calculations further predict that Bi₂Se₃ has a non-trivial energy gap larger than the energy scale k_BT at room temperature.

Abstract - Topological insulators in Bi: 2: Se: 3: , Bi: 2: Te: 3: and Sb: 2: Te: 3: with a single Dirac cone on the surface | Full Text - Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface | PDF (1,021 KB) - Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface

Subject Categories: Condensed-matter physics | Materials physics

See also: News and Views by Moore

The distribution of spatially averaged critical properties - pp444 - 447

Steven T. Bramwell

doi:10.1038/nphys1268

The distributions of the sizes of cities or earthquakes, for example, follow a power law, but in physical systems different distributions of critical properties are usually seen. A scaling argument provides a practical rule to relate the type of distribution to an experimental quantity.

Abstract - The distribution of spatially averaged critical properties | Full Text - The distribution of spatially averaged critical properties | PDF (532 KB) - The distribution of spatially averaged critical properties

Subject Category: Statistical physics, thermodynamics and nonlinear dynamics