New Gaugings and Non‐Geometry

We discuss the possible realisation in string/M theory of the recently discovered family of four‐dimensional maximal gauged supergravities, and of an analogous family of seven‐dimensional half‐maximal gauged supergravities. We first prove a no‐go theorem that neither class of gaugings can be realised via a compactification that is locally described by ten‐ or eleven‐dimensional supergravity. In the language of Double Field Theory and its M theory analogue, this implies that the section condition must be violated. Introducing the minimal number of additional coordinates possible, we then show that the standard S ³ and S ⁷ compactifications of ten‐ and eleven‐dimensional supergravity admit a new class of section‐violating generalised frames with a generalised Lie derivative algebra that reproduces the embedding tensor of the and gaugings respectively. The physical meaning, if any, of these constructions is unclear. They highlight a number of the issues that arise when attempting to apply the formalism of Double Field Theory to non‐toroidal backgrounds. Using a naive brane charge quantisation to determine the periodicities of the additional coordinates restricts the gaugings to an infinite discrete set and excludes all the gaugings other than the standard one.     

Non‐linear conductivity in Coulomb glasses

We have studied the nonlinear conductivity of two‐dimensional Coulomb glasses. We have used a Monte Carlo algorithm to simulate the dynamic of the system under an applied electric field E. We have compared results for two different models: a regular square lattice with only diagonal disorder and a random array of sites with diagonal and off‐diagonal disorder. We have found that for moderate fields the logarithm of the conductivity is proportional to , reproducing experimental results. We have also found that in the nonlinear regime the site occupancy in the Coulomb gap follows a Fermi‐Dirac distribution with an effective temperature T_eff higher than the phonon bath temperature T.     

Non‐Hermitian Gauged Topological Laser Arrays

Stable and phase‐locked emission in an extended topological supermode of coupled laser arrays, based on concepts of non‐Hermitian and topological photonics, is theoretically suggested. A non‐Hermitian Su–Schrieffer–Heeger chain of coupled microring resonators is considered, and it is shown that application of a synthetic imaginary gauge field via auxiliary passive microrings leads to all supermodes of the chain, except one, to become edge states. The only extended supermode, that retains some topological protection, can stably oscillate suppressing all other non‐topological edge supermodes. Numerical simulations based on a rate equation model of the semiconductor laser arrays confirm stable anti‐phase laser emission in the extended topological supermode and the role of the synthetic gauge field to enhance laser stability.     

Non‐uniform nanosecond gate‐delay of hybrid pixel detectors

A simple experiment to characterize the gating properties of X‐ray area detectors using pulsed X‐ray sources is presented. For a number of time‐resolved experiments the gating uniformity of area detectors is important. Relative gating delays between individual modules and readout chips of PILATUS2 series area X‐ray detectors have been observed. For three modules of a PILATUS 300K‐W unit the maximum gating offset between the modules is found to be as large as 30 ns. On average, the first photosensor module is found to be triggered 15 ns and 30 ns later than the second and the third modules, respectively.     

Non‐equilibrium polaritonics ‐ non‐linear effects and optical switching

This erratum refers to the article above, first published online on 31 December 2012 and later in print in Annalen der Physik, 525(1–2), 66–73 (2013).     

Non‐thermal plasma‐induced apoptosis in yeast Saccharomyces cerevisiae

The effect of non‐thermal plasma generated by the direct current (DC) corona discharge in the mode of transition spark is studied on a yeast Saccharomyces cerevisiae. The exposure to plasma increases production of reactive oxygen species (ROS) in cells, possibly causing the induction of apoptosis. To clarify the mechanism of apoptosis, its induction is tested not only on a wild strain of S. cerevisiae, but also on mutant strains: A deletion mutant Δyca1 without yeast metacaspase proves that in S. cerevisiae the apoptosis occurs partly by the caspase‐independent pathway. A petite strains with mutation in the mitochondria do not show pronounced ROS formation, but in spite of this, apoptosis is detected. Hence, mitochondrial ROS probably do not play an important role in induction of apoptosis.     

Non‐linear Realizations and Higher Curvature Supergravity

We focus on non‐linear realizations of local supersymmetry as obtained by using constrained superfields in supergravity. New constraints, beyond those of rigid supersymmetry, are obtained whenever curvature multiplets are affected as well as higher derivative interactions are introduced. In particular, a new constraint, which removes a very massive gravitino is introduced, and in the rigid limit it merely reduces to an explicit supersymmetry breaking. Higher curvature supergravities free of ghosts and instabilities are also obtained in this way. Finally, we consider direct coupling of the goldstino multiplet to the super Gauss–Bonnet multiplet and discuss the emergence of a new scalar degree of freedom.     

Equilibrium and Non‐Equilibrium Melting of Two‐Dimensional Plasma Crystals

Recent progress in experimental and theoretical studies of melting of two‐dimensional (2D) plasma crystals is summarized. Several generic, equilibrium and non‐equilibrium processes which can be observed and investigated in 2D complex plasmas are discussed, such as KTHNY, grain‐boundary‐induced, and shear‐induced melting. Furthermore, the key features of the dominant plasma‐specific mechanism of melting operating in 2D plasma crystals, the mode‐coupling instability, are presented. The onset of the instability, which is characterized by threshold values of the experimental parameters, identifies the “dividing line” between the regimes when 2D complex plasmas can be employed to study generic strong‐coupling phenomena, and the situations when the melting occurs due to specific processes peculiar to complex plasmas. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Non‐magnetic defects in the bulk of two‐dimensional topological insulators

We found that non‐magnetic defects in two‐dimensional topological insulators induce bound states of two kinds for each spin orientation: electron‐ and hole‐like states. Depending on the sign of the defect potential these states can be also of two kinds with different distribution of the electron density. The density has a maximum or minimum in the center. A surprising effect caused by the topological order is a singular dependence of the bound‐state energy on the defect potential.

     

Non‐invasive depth profiling by space and time‐resolved Raman spectroscopy

Time‐resolved Raman spectroscopy, spatially offset Raman spectroscopy and time‐resolved spatially offset Raman spectroscopy (TR‐SORS) have proven their capability for the non‐invasive profiling of deep layers of a sample. Recent studies have indicated that TR‐SORS exhibits an enhanced selectivity toward the deep layers of a sample. However, the enhanced depth profiling efficiency of TR‐SORS, in comparison with time‐resolved Raman spectroscopy and spatially offset Raman spectroscopy, is yet to be assessed and explained in accordance to the synergistic effects of spatial and temporal resolutions. This study provides a critical investigation of the depth profiling efficiency of the three deep Raman techniques. The study compares the efficiency of the various deep Raman spectroscopy techniques for the stand‐off detection of explosive precursors hidden in highly fluorescing packaging. The study explains for the first time the synergistic effects of spatial and temporal resolutions in the deep Raman techniques and their impact on the acquired spectral data. Copyright © 2013 John Wiley & Sons, Ltd.     

Non‐paraxial polarization spatio‐temporal coupling in ultrafast laser material processing

Two hundred years after Malus' discovery of optical anisotropy, the study of polarization‐driven optical effects is as active as ever, generating interest in new phenomena and potential applications. However, in ultrafast optics, the influence of polarization is frequently overlooked being considered as either detrimental or negligible. Here we demonstrate that spatio‐temporal couplings, which are inherent for ultrafast laser systems with chirped‐pulse amplification, accumulate in multi‐pulse irradiation and lead to a strongly anisotropic light‐matter interaction. Our results identify angular dispersion in the focus as the origin for the polarization dependence in modification, yielding an increase in modification strength. With tight focusing (NA ≥ ∼0.4), this non‐paraxial effect leads to a manifestation of spatio‐temporal couplings in photo‐induced modification. We devise a practical way to control the polarization dependence and exploit it as a new degree of freedom in tailoring laser‐induced modification in transparent material. A near‐focus, non‐paraxial field structure analysis of an optical beam provides insight on the origin of the polarization dependent modification. However, single pulse non‐paraxial corrected calculations are not sufficient to explain the phenomena confirming the experimental observations and exemplifying the need for multi‐pulse analysis.

     

Non‐invasive time‐course imaging of apoptotic cells by confocal Raman micro‐spectroscopy

Confocal Raman micro‐spectroscopy (CRMS) was used to measure time‐course spectral images of live cells undergoing apoptosis without using molecular labels or other invasive procedures. Human breast cancer cells (MDA‐MB‐231) were exposed to 300 µM etoposide to induce apoptosis, and Raman spectral images were acquired from the same cells at 2‐h intervals over a period of 6 h. The purpose‐built inverted confocal Raman micro‐spectrometer integrated an environmental enclosure and wide‐field fluorescence imaging. These key instrumental elements allowed the cells to be maintained under sterile physiological conditions (37 °C, 5% CO₂) and enabled viability and apoptosis assays to be carried out on the cells at the end of CRMS measurements. The time‐course spectral images corresponding to DNA Raman bands indicated an increase in signal intensity in apoptotic cells, which was attributed to DNA condensation. The Raman spectral images of lipids indicated a high accumulation of membrane phospholipids and highly unsaturated non‐membrane lipids in apoptotic cells. This study demonstrates the potential of CRMS for label‐free time‐course imaging of individual live cells. This technique may become a useful tool for in vitro toxicological studies and testing of new pharmaceuticals, as well as other time‐dependent cellular processes, such as cell differentiation, cell cycle and cell–cell interactions. Copyright © 2010 John Wiley & Sons, Ltd.     

Non‐Ideal Dust Structures in Cryogenic Complex Plasmas

The possibility of the formation of dust structures in cryogenic environment at 4.2‐77 K was proved experimentally in the previous researches of cryogenic complex (dusty) plasma [1–5]. It was revealed from the experiments, among others, that the dust structures with high concentration of dust particles can be formed, in which interparticle distance is comparable with particle size ‐ super dense dusty plasma structures. Such structures had exotic properties such as globular (spherical) form, free boundaries, etc. In the present work new results on the experimental investigations of new phenomenon of spheroidizing ‐ process of the dust structure transition to compact globular shape at cryogenic temperatures ‐ were presented. Possible nature of such phenomenon is discussed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Non‐electromagnetically induced transparency mechanisms for slow light

We show how the pump‐induced sharp holes in homogeneously or inhomogeneously broadened absorption line shapes can be used for the production of ultra‐slow light. We present a detailed discussion of underlying concepts and results on the pump power dependences of the group index and the bandwidth–delay product. Further, we discuss experimental results, which are in agreement with theoretical predictions.     

Quantum Probing Topological Phase Transitions by Non‐Markovianity

Understanding the physical significance and probing the global invariants characterizing quantum topological phases in extended systems is a main challenge in modern physics with major impact in different areas of science. Here, a quantum‐information‐inspired probing method is proposed where topological phase transitions are revealed by a non‐Markovianity quantifier. The idea is illustrated by considering the decoherence dynamics of an external read‐out qubit that probes a Su–Schrieffer–Heeger (SSH) chain with either pure dephasing or dissipative coupling. Qubit decoherence features and non‐Markovianity measure clearly signal the topological phase transition of the SSH chain.     

Non‐interacting single‐impurity Anderson model: solution without using the equation‐of‐motion method

Ground‐state properties of the non‐interacting symmetric single‐impurity Anderson model (SIAM) are derived from the corresponding eigenenergy equation. Explicit formulae are given for the ground‐state energy, the hybridization, and the momentum distribution that are essential quantities for variational approaches to the interacting model. Various spectral functions, e.g., the total density of states, the phase shift function, and the impurity spectral function, are shown to agree with those obtained from the equation‐of‐motion method (see supplementary material). For a constant hybridization strength and a semi‐elliptic host density of states it is seen that the impurity spectral function builds up weight at the band edges.

     

Non‐Locality Effects in Excitation and Spatial Propagation of Surface Plasmon‐Polaritons

This work investigates the influence of non‐locality in the dielectric response on the spatio‐temporal evolution of surface plasmon‐polaritons (SPP). SPP excitations are coherently generated by a quantum scatterer in the vicinity of a flat metal interface. It is demonstrated that the excited non‐equilibrium SPP population eventually splits into two coherent localized wave packets. One packet propagates along the interface and the other is centered in the vicinity of the scatter. The amplitude of both waves slowly decreases due to several relaxation mechanisms, with the Landau damping being the strongest. The non‐locality of the metallic dielectric response considerably influences spatial profiles of the plasmon field intensity, in particular, leading to coherent spatio‐temporal oscillations between the two wave packets.