Showing papers on "Field (physics) published in 2017"
TL;DR: In this paper, the authors present experimental and theoretical developments in the field of quantum many-body systems, and present a survey of the current state of the art in this field.
Abstract: Dynamics of quantum many-body systems is one of the most complex problems in physics since it involves the time evolution of a large number of particles that interact with each other under the influence of external forces. With ultracold atoms in optical atomic lattices it can be done in a controlled environment by applying a periodic force. This Colloquium covers the experimental and theoretical developments in this exciting field of physics.
917 citations
TL;DR: In this paper, the current status of this rapidly-developing field, focusing on semiconductor-superconductor proposals for topological superconductivity, is reviewed, and several next-generation experiments probing exotic properties of Majorana zero modes are discussed.
Abstract: Realizing topological superconductivity and Majorana zero modes in the laboratory is one of the major goals in condensed matter physics. We review the current status of this rapidly-developing field, focusing on semiconductor-superconductor proposals for topological superconductivity. Material science progress and robust signatures of Majorana zero modes in recent experiments are discussed. After a brief introduction to the subject, we outline several next-generation experiments probing exotic properties of Majorana zero modes, including fusion rules and non-Abelian exchange statistics. Finally, we discuss prospects for implementing Majorana-based topological quantum computation in these systems.
548 citations
TL;DR: In this article, a well-tested, three-dimensional, transient heat transfer and fluid flow model is used to accurately calculate transient temperature field for the residual stress and distortion modeling.
494 citations
TL;DR: In this article, a review summarizes how insights from mesoscopic scattering theory have direct relevance for optical wave control experiments and vice versa, and the results are expected to have an impact on a number of fields ranging from biomedical imaging to nanophotonics, quantum information, and communication technology.
Abstract: Wave front shaping, the ability to manipulate light fields both spatially and temporally, in complex media is an emerging field with many applications. This review summarizes how insights from mesoscopic scattering theory have direct relevance for optical wave control experiments and vice versa. The results are expected to have an impact on a number of fields ranging from biomedical imaging to nanophotonics, quantum information, and communication technology.
492 citations
TL;DR: In this article, a stable class of spin liquids described by higher-rank tensor gauge fields was studied. And they showed that these spin liquids feature an exotic class of excitations that are restricted to motion along lower-dimensional subspaces.
Abstract: Quantum spin liquids can be well described in the language of gauge theory. While most theoretical effort has been focused on gauge theories with a familiar vector gauge field, there exists a stable class of quantum spin liquids described by higher-rank tensor gauge fields. Here, the authors focus on a class of stable three-dimensional spin liquids described by symmetric tensor $U$(1) gauge fields. They find that these spin liquids feature an exotic class of excitations that are restricted to motion along lower-dimensional subspaces, a phenomenon seen earlier in fracton models. They show how this subdimensional behavior follows naturally from a set of higher-moment charge conservation laws that place severe restrictions on particle motion. This work opens up an exciting new direction in the field of spin liquids.
332 citations
TL;DR: In this article, the authors present some of the phenomena and possible applications arising from the interaction of light with particles with a refractive index less than 2, and draw an overview of the possible applications of such materials, in connection with field enhancement and super resolution nanoscopy.
Abstract: Materials with relatively small refractive indices (n<2), such as glass, quartz, polymers, some ceramics, etc., are the basic materials in most optical components (lenses, optical fibres, etc.). In this review, we present some of the phenomena and possible applications arising from the interaction of light with particles with a refractive index less than 2. The vast majority of the physics involved can be described with the help of the exact, analytical solution of Maxwell’s equations for spherical particles (so called Mie theory). We also discuss some other particle geometries (spheroidal, cubic, etc.) and different particle configurations (isolated or interacting) and draw an overview of the possible applications of such materials, in connection with field enhancement and super resolution nanoscopy.
311 citations
TL;DR: Stochastic thermodynamics as mentioned in this paper extends the traditional laws of thermodynamics to microscopic systems where thermal and quantum fluctuations cannot be ignored, and a review summarizes progress in this field with a look at several experimental and theoretical results and a look toward potential applications in biology and nanotechnology.
Abstract: Stochastic thermodynamics extends the traditional laws of thermodynamics to microscopic systems where thermal and quantum fluctuations cannot be ignored. This review summarizes progress in this field with a look at several experimental and theoretical results and a look toward potential applications in biology and nanotechnology.
278 citations
Max Planck Society1, University of Rostock2, ETH Zurich3, Pohang University of Science and Technology4, ICFO – The Institute of Photonic Sciences5, University College London6, Imperial College London7, Weizmann Institute of Science8, University of Erlangen-Nuremberg9, Ludwig Maximilian University of Munich10
TL;DR: This report on progress presents a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures, and elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics.
Abstract: Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto-and sub-femtosecondtime scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond = 1 as = 10-(18)s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is similar to 152 as. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this report on progress we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser- driven electron dynamics. Consequently, this has important impact on pivotal processes such as above-threshold ionization and high-order harmonic generation. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nanophysics has begun, but it is in the initial stage. We present thus some of the open questions, challenges and prospects for experimental confirmation of theoretical predictions, as well as experiments aimed at characterizing the induced fields and the unique electron dynamics initiated by them with high temporal and spatial resolution.
256 citations
TL;DR: A critical review of recent results in the graphene thermal field focusing on phonon dispersion, specific heat, thermal conductivity, and comparison of different models and computational approaches is provided in this article.
Abstract: A discovery of the unusual thermal properties of graphene stimulated experimental, theoretical and computational research directed at understanding phonon transport and thermal conduction in two-dimensional material systems. We provide a critical review of recent results in the graphene thermal field focusing on phonon dispersion, specific heat, thermal conductivity, and comparison of different models and computational approaches. The correlation between the phonon spectrum in graphene-based materials and the heat conduction properties is analyzed in details. The effects of the atomic plane rotations in bilayer graphene, isotope engineering, and relative contributions of different phonon dispersion branches are discussed. For readers' convenience, the summaries of main experimental and theoretical results on thermal conductivity as well as phonon mode contributions to thermal transport are provided in the form of comprehensive annotated tables.
255 citations
Posted Content•
TL;DR: The relativistic viscous fluid dynamics was formulated from first principles in an effective field theory framework, based entirely on the knowledge of symmetries and long-lived degrees of freedom.
Abstract: Ten years ago, relativistic viscous fluid dynamics was formulated from first principles in an effective field theory framework, based entirely on the knowledge of symmetries and long-lived degrees of freedom. In the same year, numerical simulations for the matter created in relativistic heavy-ion collision experiments became first available, providing constraints on the shear viscosity in QCD. The field has come a long way since then. We present the current status of the theory of non-equilibrium fluid dynamics in 2017, including the divergence of the fluid dynamic gradient expansion, resurgence, non-equilibrium attractor solutions, the inclusion of thermal fluctuations as well as their relation to microscopic theories. Furthermore, we review the theory basis for numerical fluid dynamics simulations of relativistic nuclear collisions, and comparison of modern simulations to experimental data for nucleus-nucleus, nucleus-proton and proton-proton collisions.
254 citations
TL;DR: It is shown that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moiré patterns that introduce twist-angle dependent satellite excitonic peaks.
Abstract: Moir\'e patterns are common in van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. We show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moir\'e patterns that introduce twist-angle dependent satellite excitonic peaks. Topological exciton bands with nonzero Chern numbers that support chiral excitonic edge states can be engineered by combining three ingredients: (i) the valley Berry phase induced by electron-hole exchange interactions, (ii) the moir\'e potential, and (iii) the valley Zeeman field.
TL;DR: These localized fields are proved to effectively promote the detection ability of 2DPDs by suppressing background noise, enhancing optical absorption, improving electron-hole separation efficiency, amplifying photoelectric gain and/or extending the detection range.
Abstract: Two-dimensional (2D) materials have drawn tremendous attention in recent years. Being atomically thin, stacked with van der Waals force and free of surface chemical dangling bonds, 2D materials exhibit several distinct physical properties. To date, 2D materials include graphene, transition metal dichalcogenides (TMDS), black phosphorus, black P(1-x) Asx , boron nitride (BN) and so forth. Owing to their various bandgaps, 2D materials have been utilized for photonics and optoelectronics. Photodetectors based on 2D materials with different structures and detection mechanisms have been established and present excellent performance. In this Review, localized field enhanced 2D material photodetectors (2DPDs) are introduced with sensitivity over the spectrum from ultraviolet, visible to infrared in the sight of the influence of device structure on photodetector performance instead of directly illustrating the detection mechanisms. Six types of localized fields are summarized. They are: ferroelectric field, photogating electric field, floating gate induced electrostatic field, interlayer built-in field, localized optical field, and photo-induced temperature gradient field, respectively. These localized fields are proved to effectively promote the detection ability of 2DPDs by suppressing background noise, enhancing optical absorption, improving electron-hole separation efficiency, amplifying photoelectric gain and/or extending the detection range.
TL;DR: This work reports a new method of microscopic liquid transport based on a unique topological structure that allows for a rapid, directional, and long-distance transport of virtually any kind of liquid without the need for an external energy input.
Abstract: The last two decades have witnessed an explosion of interest in the field of droplet-based microfluidics for their multifarious applications. Despite rapid innovations in strategies to generate small-scale liquid transport on these devices, the speed of motion is usually slow, the transport distance is limited, and the flow direction is not well controlled because of unwanted pinning of contact lines by defects on the surface. We report a new method of microscopic liquid transport based on a unique topological structure. This method breaks the contact line pinning through efficient conversion of excess surface energy to kinetic energy at the advancing edge of the droplet while simultaneously arresting the reverse motion of the droplet via strong pinning. This results in a novel topological fluid diode that allows for a rapid, directional, and long-distance transport of virtually any kind of liquid without the need for an external energy input.
TL;DR: In this article, the exact solution for the scattering problem in the flat space Jackiw-Teitelboim (JT) gravity coupled to an arbitrary quantum field theory was presented.
Abstract: We present the exact solution for the scattering problem in the flat space Jackiw-Teitelboim (JT) gravity coupled to an arbitrary quantum field theory. JT gravity results in a gravitational dressing of field theoretical scattering amplitudes. The exact expression for the dressed $S$-matrix was previously known as a solvable example of a novel UV asymptotic behavior, dubbed asymptotic fragility. This dressing is equivalent to the $T\bar{T}$ deformation of the initial quantum field theory. JT gravity coupled to a single massless boson provides a promising action formulation for an integrable approximation to the worldsheet theory of confining strings in 3D gluodynamics. We also derive the dressed $S$-matrix as a flat space limit of the near $AdS_2$ holography. We show that in order to preserve the flat space unitarity the conventional Schwarzian dressing of boundary correlators needs to be slightly extended. Finally, we propose a new simple expression for flat space amplitudes of massive particles in terms of correlators of holographic CFT's.
TL;DR: In this paper, the exact solution for the scattering problem in the flat space Jackiw-Teitelboim (JT) gravity coupled to an arbitrary quantum field theory was presented.
Abstract: We present the exact solution for the scattering problem in the flat space Jackiw-Teitelboim (JT) gravity coupled to an arbitrary quantum field theory. JT gravity results in a gravitational dressing of field theoretical scattering amplitudes. The exact expression for the dressed S-matrix was previously known as a solvable example of a novel UV asymptotic behavior, dubbed asymptotic fragility. This dressing is equivalent to the $$ T\overline{T} $$
deformation of the initial quantum field theory. JT gravity coupled to a single mass-less boson provides a promising action formulation for an integrable approximation to the worldsheet theory of confining strings in 3D gluodynamics. We also derive the dressed S-matrix as a flat space limit of the near AdS2 holography. We show that in order to preserve the flat space unitarity the conventional Schwarzian dressing of boundary correlators needs to be slightly extended. Finally, we propose a new simple expression for flat space amplitudes of massive particles in terms of correlators of holographic CFT’s.
TL;DR: The first report of infinite-range interactions between macroscopically separated atomic dipoles mediated by an optical waveguide is presented, and super-radiance of a few atoms separated by hundreds of resonant wavelengths is observed.
Abstract: Atoms interact with each other through the electromagnetic field, creating collective states that can radiate faster or slower than a single atom, i.e., super- and sub-radiance. When the field is confined to one dimension it enables infinite-range atom-atom interactions. Here we present the first report of infinite-range interactions between macroscopically separated atomic dipoles mediated by an optical waveguide. We use cold 87Rb atoms in the vicinity of a single-mode optical nanofiber (ONF) that coherently exchange evanescently coupled photons through the ONF mode. In particular, we observe super-radiance of a few atoms separated by hundreds of resonant wavelengths. The same platform allows us to measure sub-radiance, a rarely observed effect, presenting a unique tool for quantum optics. This result constitutes a proof of principle for collective behavior of macroscopically delocalized atomic states, a crucial element for new proposals in quantum information and many-body physics.
TL;DR: In this paper, the authors present an implementation of density functional perturbation theory tailored to simulate the electronic and vibrational properties of two-dimensional heterostructures in the field effect configuration.
Abstract: In the search for exciting new physics and the design of next-generation devices, gated two-dimensional heterostructures are becoming omnipresent As the fabrication and characterization techniques in this field improve, first-principles methods must follow suit The authors present here an implementation of density functional perturbation theory, tailored to simulate the electronic and vibrational properties of two-dimensional heterostructures in the field-effect configuration They apply the method to gated graphene and show that while the field effect activates the coupling between electrons and flexural phonons, this coupling is strongly screened by the electrons of doped graphene
TL;DR: In this article, the correlation between the baryon-to-entropy ratio produced by electroweak baryogenesis and the gravitational wave signal from the electroweak phase transition was studied.
Abstract: We consider a real scalar singlet field which provides a strong first-order electroweak phase transition via its coupling to the Higgs boson, and gives a $CP$ violating contribution on the top quark mass via a dimension-6 operator. We study the correlation between the baryon-to-entropy ratio produced by electroweak baryogenesis, and the gravitational wave signal from the electroweak phase transition. We show that future gravitational wave experiments can test, in particular, the region of the model parameter space where the observed baryon-to-entropy ratio can be obtained even if the new physics scale, which is explicit in the dimension-6 operator, is high.
TL;DR: In this paper, structural tensors are employed to describe transverse isotropy, orthotropy and cubic anisotropy in fracture phase field models, and the authors demonstrate the performance of the proposed anisotropic fracture model by means of representative numerical examples at small and large deformations.
Abstract: A phase field model of fracture that accounts for anisotropic material behavior at small and large deformations is outlined within this work. Most existing fracture phase field models assume crack evolution within isotropic solids, which is not a meaningful assumption for many natural as well as engineered materials that exhibit orientation-dependent behavior. The incorporation of anisotropy into fracture phase field models is for example necessary to properly describe the typical sawtooth crack patterns in strongly anisotropic materials. In the present contribution, anisotropy is incorporated in fracture phase field models in several ways: (i) Within a pure geometrical approach, the crack surface density function is adopted by a rigorous application of the theory of tensor invariants leading to the definition of structural tensors of second and fourth order. In this work we employ structural tensors to describe transverse isotropy, orthotropy and cubic anisotropy. Latter makes the incorporation of second gradients of the crack phase field necessary, which is treated within the finite element context by a nonconforming Morley triangle. Practically, such a geometric approach manifests itself in the definition of anisotropic effective fracture length scales. (ii) By use of structural tensors, energetic and stress-like failure criteria are modified to account for inherent anisotropies. These failure criteria influence the crack driving force, which enters the crack phase field evolution equation and allows to set up a modular structure. We demonstrate the performance of the proposed anisotropic fracture phase field model by means of representative numerical examples at small and large deformations.
TL;DR: This review provides a summary of the rich physics expressed within SrTiO3-based heterostructure and nanostructures, including their phase diagram and coupling between the various degrees of freedom.
Abstract: This review provides a summary of the rich physics expressed within SrTiO$_3$-based heterostructures and nanostructures. The intended audience is researchers who are working in the field of oxides, but also those with different backgrounds (e.g., semiconductor nanostructures). After reviewing the relevant properties of SrTiO$_3$ itself, we will then discuss the basics of SrTiO$_3$-based heterostructures, how they can be grown, and how devices are typically fabricated. Next, we will cover the physics of these heterostructures, including their phase diagram and coupling between the various degrees of freedom. Finally, we will review the rich landscape of quantum transport phenomena, as well as the devices that elicit them.
TL;DR: In this article, a pure spin current source with large spin Hall angle (SHE) and high electrical conductivity was proposed for spin-orbit-torque switching using the spin Hall effect in heavy metals and topological insulators.
Abstract: Spin-orbit-torque (SOT) switching using the spin Hall effect (SHE) in heavy metals and topological insulators (TIs) has great potential for ultra-low power magnetoresistive random-access memory (MRAM) To be competitive with conventional spin-transfer-torque (STT) switching, a pure spin current source with large spin Hall angle (${\theta}_{SH}$ > 1) and high electrical conductivity (${\sigma} > 10^5 {\Omega}^{-1}m^{-1}$) is required Here, we demonstrate such a pure spin current source: BiSb thin films with ${\sigma}{\sim}25*10^5 {\Omega}^{-1}m^{-1}$, ${\theta}_{SH}{\sim}52$, and spin Hall conductivity ${\sigma}_{SH}{\sim}13*10^7 {\hbar}/2e{\Omega}^{-1}m^{-1}$ at room temperature We show that BiSb thin films can generate a colossal spin-orbit field of 2770 Oe/(MA/cm$^2$) and a critical switching current density as low as 15 MA/cm$^2$ in Bi$_{09}$Sb$_{01}$ / MnGa bi-layers BiSb is the best candidate for the first industrial application of topological insulators
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27 Oct 2017TL;DR: In this paper, the phase field model is used to numerically simulate the solidification of a pure material and the results depend on the interface thickness and with a simple numerical scheme employed it is not practical to do computations with an interface that is sufficiently thin for the numerical solution to accurately represent a sharp interface model.
Abstract: A phase field model is used to numerically simulate the solidification of a pure material. We employ it to compute growth into an undercooled liquid for a one-dimensional spherically symmetric geometry and a planar two-dimensional rectangular region. The phase field model equation are solved using finite difference techniques on a uniform mesh. For the growth of a sphere, the solutions from the phase field equations for sufficiently small interface widths are in good agreement with a numerical solution to the classical sharp interface model obtained using a Green's function approach. In two dimensions, we simulate dendritic growth of nickel with four-fold anisotropy and investigate the effect of the level of anisotropy on the growth of a dendrite. The quantitative behavior of the phase field model is evaluated for varying interface thickness and spatial and temporal resolution. We find quantitatively that the results depend on the interface thickness and with the simple numerical scheme employed it is not practical to do computations with an interface that is sufficiently thin for the numerical solution to accurately represent a sharp interface model. However, even with a relatively thick interface the results from the phase field model show many of the features of dendritic growth and they are in surprisingly good quantitative agreement with the Ivantsov solution and microscopic solvability theory.
TL;DR: A comprehensive guide to nano-impact experiments is presented, in which newcomers to this rapidly-developing field of research are introduced and common-encountered issues are considered and presented alongside methods for their solutions.
Abstract: We present a comprehensive guide to nano-impact experiments, in which we introduce newcomers to this rapidly-developing field of research. Central questions are answered regarding required experimental set-ups, categories of materials that can be detected, and the theoretical frameworks enabling the analysis of experimental data. Commonly-encountered issues are considered and presented alongside methods for their solutions.
TL;DR: In this article, the authors reported experimental evidence of strong radiation reaction, in an all-optical experiment, during the propagation of highly relativistic electrons (maximum energy exceeding 2 GeV) through the field of an ultra-intense laser (peak intensity of $4\times10^{20}$ W/cm$^2$).
Abstract: The description of the dynamics of an electron in an external electromagnetic field of arbitrary intensity is one of the most fundamental outstanding problems in electrodynamics. Remarkably, to date there is no unanimously accepted theoretical solution for ultra-high intensities and little or no experimental data. The basic challenge is the inclusion of the self-interaction of the electron with the field emitted by the electron itself - the so-called radiation reaction force. We report here on the experimental evidence of strong radiation reaction, in an all-optical experiment, during the propagation of highly relativistic electrons (maximum energy exceeding 2 GeV) through the field of an ultra-intense laser (peak intensity of $4\times10^{20}$ W/cm$^2$). In their own rest frame, the highest energy electrons experience an electric field as high as one quarter of the critical field of quantum electrodynamics and are seen to lose up to 30% of their kinetic energy during the propagation through the laser field. The experimental data show signatures of quantum effects in the electron dynamics in the external laser field, potentially showing departures from the constant cross field approximation.
TL;DR: Two distinct algorithms are presented: a self-consistent field method and a direct variational free energy minimization method using auxiliary Hamiltonians (GC-AuxH), to solve the Kohn-Sham equations of electronic density-functional theory directly in the grand canonical ensemble at fixed potential.
Abstract: First-principles calculations combining density-functional theory and continuum solvation models enable realistic theoretical modeling and design of electrochemical systems. When a reaction proceeds in such systems, the number of electrons in the portion of the system treated quantum mechanically changes continuously, with a balancing charge appearing in the continuum electrolyte. A grand-canonical ensemble of electrons at a chemical potential set by the electrode potential is therefore the ideal description of such systems that directly mimics the experimental condition. We present two distinct algorithms: a self-consistent field method and a direct variational free energy minimization method using auxiliary Hamiltonians (GC-AuxH), to solve the Kohn-Sham equations of electronic density-functional theory directly in the grand canonical ensemble at fixed potential. Both methods substantially improve performance compared to a sequence of conventional fixed-number calculations targeting the desired potential, with the GC-AuxH method additionally exhibiting reliable and smooth exponential convergence of the grand free energy. Finally, we apply grand-canonical density-functional theory to the under-potential deposition of copper on platinum from chloride-containing electrolytes and show that chloride desorption, not partial copper monolayer formation, is responsible for the second voltammetric peak.
TL;DR: In this article, the authors report on the unusual behavior of the in-plane thermal conductivity and torque response in the Kitaev-Heisenberg material in the presence of unconventional spin excitations whose properties are characteristic of a field-induced spin-liquid phase.
Abstract: We report on the unusual behavior of the in-plane thermal conductivity $\ensuremath{\kappa}$ and torque $\ensuremath{\tau}$ response in the Kitaev-Heisenberg material $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$. $\ensuremath{\kappa}$ shows a striking enhancement with linear growth beyond $H=7\text{ }\text{ }\mathrm{T}$, where magnetic order disappears, while $\ensuremath{\tau}$ for both of the in-plane symmetry directions shows an anomaly at the same field. The temperature and field dependence of $\ensuremath{\kappa}$ are far more complex than conventional phonon and magnon contributions, and require us to invoke the presence of unconventional spin excitations whose properties are characteristic of a field-induced spin-liquid phase related to the enigmatic physics of the Kitaev model in an applied magnetic field.
TL;DR: In this paper, the boundary central charge is the coefficient of the product of the extrinsic curvature and the Weyl curvature in the conformal anomaly in the boundary limit.
Abstract: We consider the structure of current and stress tensor two-point functions in conformal field theory with a boundary. The main result of this paper is a relation between a boundary central charge and the coefficient of a displacement operator correlation function in the boundary limit. The boundary central charge under consideration is the coefficient of the product of the extrinsic curvature and the Weyl curvature in the conformal anomaly. Along the way, we describe several auxiliary results. Three of the more notable are as follows: (1) we give the bulk and boundary conformal blocks for the current two-point function; (2) we show that the structure of these current and stress tensor two-point functions is essentially universal for all free theories; (3) we introduce a class of interacting conformal field theories with boundary degrees of freedom, where the interactions are confined to the boundary. The most interesting example we consider can be thought of as the infrared fixed point of graphene. This particular interacting conformal model in four dimensions provides a counterexample of a previously conjectured relation between a boundary central charge and a bulk central charge. The model also demonstrates that the boundary central charge can change in response to marginal deformations.
TL;DR: In this paper, the authors proposed a novel metasurface that is capable of completely controlling both amplitude and phase profiles of visible light independently with subwavelength spatial resolution, using X-shaped meta-atoms based on expanded concept of the Pancharatnam-Berry phase.
Abstract: Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technique to display three-dimensional images. Due to essential requirements for an ideal hologram, subwavelength control of both amplitude and phase is crucial. Nevertheless, traditional holographic devices have suffered from their limited capabilities of incomplete modulation in both amplitude and phase of visible light. Here, we propose a novel metasurface that is capable of completely controlling both amplitude and phase profiles of visible light independently with subwavelength spatial resolution. The simultaneous, continuous, and broadband control of amplitude and phase is achieved by using X-shaped meta-atoms based on expanded concept of the Pancharatnam-Berry phase. The first experimental demonstrations of complete complex-amplitude holograms with subwavelength definition are achieved and show excellent performances with remarkable signal-to-noise ratio compared to traditional phase-only holograms. Extraordinary control capability with versatile advantages of our metasurface paves a way to an ideal holography, which is expected to be a significant advance in the field of optical holography and metasurfaces.
TL;DR: Results confirmed that neurons exposed to external electromagnetic field can induce phase synchronization and appropriate behaviors can be selected, and could give new mechanism explanation for phase synchronization by applying field coupling between neurons.
TL;DR: It is demonstrated that the Rashba-split 2DEG at the complex oxide interface can be used for efficient charge-and-spin conversion at room temperature for the generation and detection of spin current.
Abstract: The Rashba physics has been intensively studied in the field of spin orbitronics for the purpose of searching novel physical properties and the ferromagnetic (FM) magnetization switching for technological applications. We report our observation of the inverse Edelstein effect up to room temperature in the Rashba-split two-dimensional electron gas (2DEG) between two insulating oxides, SrTiO3 and LaAlO3, with the LaAlO3 layer thickness from 3 to 40 unit cells (UC). We further demonstrate that the spin voltage could be markedly manipulated by electric field effect for the 2DEG between SrTiO3 and 3-UC LaAlO3. These results demonstrate that the Rashba-split 2DEG at the complex oxide interface can be used for efficient charge-and-spin conversion at room temperature for the generation and detection of spin current.