Showing papers on "Electromagnetic field published in 2021"
TL;DR: In this article, the authors show that the mere presence of these hybrid states can enhance properties such as transport, magnetism, and superconductivity and modify (bio)chemical reactivity.
Abstract: Over the past decade, there has been a surge of interest in the ability of hybrid light-matter states to control the properties of matter and chemical reactivity. Such hybrid states can be generated by simply placing a material in the spatially confined electromagnetic field of an optical resonator, such as that provided by two parallel mirrors. This occurs even in the dark because it is electromagnetic fluctuations of the cavity (the vacuum field) that strongly couple with the material. Experimental and theoretical studies have shown that the mere presence of these hybrid states can enhance properties such as transport, magnetism, and superconductivity and modify (bio)chemical reactivity. This emerging field is highly multidisciplinary, and much of its potential has yet to be explored.
180 citations
TL;DR: In this paper, an optically levitated femtogram (10−15 grams) dielectric particle was investigated in a cryogenic free space, which suppresses thermal effects sufficiently to make the measurement backaction the dominant decoherence mechanism.
Abstract: Tests of quantum mechanics on a macroscopic scale require extreme control over mechanical motion and its decoherence1–3. Quantum control of mechanical motion has been achieved by engineering the radiation–pressure coupling between a micromechanical oscillator and the electromagnetic field in a resonator4–7. Furthermore, measurement-based feedback control relying on cavity-enhanced detection schemes has been used to cool micromechanical oscillators to their quantum ground states8. In contrast to mechanically tethered systems, optically levitated nanoparticles are particularly promising candidates for matter-wave experiments with massive objects9,10, since their trapping potential is fully controllable. Here we optically levitate a femtogram (10−15 grams) dielectric particle in cryogenic free space, which suppresses thermal effects sufficiently to make the measurement backaction the dominant decoherence mechanism. With an efficient quantum measurement, we exert quantum control over the dynamics of the particle. We cool its centre-of-mass motion by measurement-based feedback to an average occupancy of 0.65 motional quanta, corresponding to a state purity of 0.43. The absence of an optical resonator and its bandwidth limitations holds promise to transfer the full quantum control available for electromagnetic fields to a mechanical system. Together with the fact that the optical trapping potential is highly controllable, our experimental platform offers a route to investigating quantum mechanics at macroscopic scales11. Quantum control of an optically levitated nanoparticle with a mass of just one femtogram is demonstrated in a cryogenic environment by feedback-cooling the motion of the particle to the quantum ground state.
123 citations
TL;DR: In this article, a femto-gram dielectric particle is optically levitated in a cryogenic free space, which suppresses thermal effects sufficiently to make the measurement backaction the dominant decoherence mechanism.
Abstract: Tests of quantum mechanics on a macroscopic scale require extreme control over mechanical motion and its decoherence. Quantum control of mechanical motion has been achieved by engineering the radiation-pressure coupling between a micromechanical oscillator and the electromagnetic field in a resonator. Furthermore, measurement-based feedback control relying on cavity-enhanced detection schemes has been used to cool micromechanical oscillators to their quantum ground states. In contrast to mechanically tethered systems, optically levitated nanoparticles are particularly promising candidates for matter-wave experiments with massive objects, since their trapping potential is fully controllable. In this work, we optically levitate a femto-gram dielectric particle in cryogenic free space, which suppresses thermal effects sufficiently to make the measurement backaction the dominant decoherence mechanism. With an efficient quantum measurement, we exert quantum control over the dynamics of the particle. We cool its center-of-mass motion by measurement-based feedback to an average occupancy of 0.65 motional quanta, corresponding to a state purity of 43%. The absence of an optical resonator and its bandwidth limitations holds promise to transfer the full quantum control available for electromagnetic fields to a mechanical system. Together with the fact that the optical trapping potential is highly controllable, our experimental platform offers a route to investigating quantum mechanics at macroscopic scales.
97 citations
18 Aug 2021
TL;DR: In this paper, the authors introduce the concept of interactive quantum information sensing, tailored to provable verification of weak dynamical entanglement generation between a pair of systems, and show that this protocol is highly robust to typical thermal noise sources.
Abstract: If gravitational perturbations are quantized into gravitons in analogy with the electromagnetic field and photons, the resulting graviton interactions should lead to an entangling interaction between massive objects. We suggest a test of this prediction. To do this, we introduce the concept of interactive quantum information sensing. This novel sensing protocol is tailored to provable verification of weak dynamical entanglement generation between a pair of systems. We show that this protocol is highly robust to typical thermal noise sources. Moreover, the sensitivity can be increased both using an initial thermal state and/or an initial phase of entangling via a nongravitational interaction. We outline a concrete implementation testing the ability of the gravitational field to generate entanglement between an atomic interferometer and a mechanical oscillator. Preliminary numerical estimates suggest that near-term devices could feasibly be used to perform the experiment.
65 citations
TL;DR: In this paper, the main novelty of giant atoms is that the multiple coupling points give rise to interference effects that are not present in quantum optics with ordinary, small atoms, and discuss both theoretical and experimental results for single and multiple giant atoms.
Abstract: In quantum optics, it is common to assume that atoms can be approximated as point-like compared to the wavelength of the light they interact with. However, recent advances in experiments with artificial atoms built from superconducting circuits have shown that this assumption can be violated. Instead, these artificial atoms can couple to an electromagnetic field at multiple points, which are spaced wavelength distances apart. In this chapter, we present a survey of such systems, which we call giant atoms. The main novelty of giant atoms is that the multiple coupling points give rise to interference effects that are not present in quantum optics with ordinary, small atoms. We discuss both theoretical and experimental results for single and multiple giant atoms, and show how the interference effects can be used for interesting applications. We also give an outlook for this emerging field of quantum optics.
65 citations
TL;DR: In this paper, a transmon qubit coupled to propagating microwaves at multiple points along an open transmission line was investigated, where the qubit radiation field can interfere with itself, leading to some striking giant-atom effects.
Abstract: Engineering light-matter interactions at the quantum level has been central to the pursuit of quantum optics for decades. Traditionally, this has been done by coupling emitters, typically natural atoms and ions, to quantized electromagnetic fields in optical and microwave cavities. In these systems, the emitter is approximated as an idealized dipole, as its physical size is orders of magnitude smaller than the wavelength of light. Recently, artificial atoms made from superconducting circuits have enabled new frontiers in light-matter coupling, including the study of ``giant'' atoms which cannot be approximated as simple dipoles. Here, we explore an implementation of a giant artificial atom, formed from a transmon qubit coupled to propagating microwaves at multiple points along an open transmission line. The nature of this coupling allows the qubit radiation field to interfere with itself, leading to some striking giant-atom effects. For instance, we observe strong frequency-dependent couplings of the qubit energy levels to the electromagnetic modes of the transmission line. Combined with the ability to in situ tune the qubit energy levels, we show that we can modify the relative coupling rates of multiple qubit transitions by more than an order of magnitude. By doing so, we engineer a metastable excited state, allowing us to operate the giant transmon as an effective lambda system where we clearly demonstrate electromagnetically induced transparency.
60 citations
TL;DR: In this article, the authors revisited the interaction of a first-quantized atomic system with the quantum electromagnetic field, pointing out the subtleties related to the gauge nature of electromagnetism and the effect of multipole approximations.
Abstract: We revisit the interaction of a first-quantized atomic system (consisting of two charged quantum particles) with the quantum electromagnetic field, pointing out the subtleties related to the gauge nature of electromagnetism and the effect of multipole approximations. We connect the full minimal-coupling model with the typical effective models used in quantum optics and relativistic quantum information such as the Unruh-DeWitt (UDW) model and the dipole coupling approximation. We point out in what regimes different degrees of approximation are reasonable and in what cases effective models need to be refined to capture the features of the light-matter interaction. This is particularly important when considering the center of mass (COM) of the atom as a quantum system that can be delocalized over multiple trajectories. For example, we show that the simplest UDW approximation with a quantum COM fails to capture crucial R\"ontgen terms coupling COM and internal atomic degrees of freedom with each other and the field. Finally we show how effective dipole interaction models can be covariantly prescribed for relativistically moving atoms.
56 citations
TL;DR: In this paper, the authors proposed a time-modulated reflective metasurface that causes a frequency shift to the impinging radiation, thus realizing an artificial Doppler effect in a nonmoving electrically thin structure.
Abstract: Metasurfaces consisting of electrically thin and densely packed planar arrays of subwavelength elements enable an unprecedented control of the impinging electromagnetic fields. Spatially modulated metasurfaces can efficiently tailor the spatial distribution of these fields with great flexibility. Similarly, time modulated metasurfaces can be successfully used to manipulate the frequency content and time variations of the impinging field. In this paper, we present time-modulated reflective metasurfaces that cause a frequency shift to the impinging radiation, thus realizing an artificial Doppler effect in a non-moving electrically thin structure. Starting from the theoretical analysis, we analytically derive the required time modulation of the surface admittance to achieve this effect, and present a realistic time-varying structure, based on a properly designed and dynamically tuned high-impedance surface. It is analytically and numerically demonstrated that the field emerging from the metasurface is up-,down-converted in frequency according to the modulation profile of the metasurface. The proposed metasurface concept, enabling a frequency modulation of the electromagnetic field on-the-fly, may find application in telecommunication, radar, and sensing scenarios.
50 citations
TL;DR: In this article, the authors presented transformation equations for electromagnetic fields of polarized light ray traveling by magnetic optical fiber on De Sitter space S 1 2, where the new spherical frame of some Lorentzian spherical systems that are illustrated simultaneously with co-ciled magnetic optical fibre was illustrated in De Satter space.
49 citations
TL;DR: In this article, MnO@N-doped carbon nanotubes with adjustable carbon layer were synthesized by thermal decomposition of pyrrole on the surface of MnO2 nanotube for electromagnetic absorption application, and the morphology, composition, internal defects, conductivity and electromagnetic parameters of the composites were investigated.
47 citations
TL;DR: In this article, the authors describe a family of supertoroidal light pulses that exhibit skyrmionic topological structure flying in free space, and they are of interest for transient light-matter interactions, ultrafast optics, spectroscopy, and toroidal electrodynamics.
Abstract: Topological complex transient electromagnetic fields give access to nontrivial light-matter interactions and provide additional degrees of freedom for information transfer. An important example of such electromagnetic excitations are space-time non-separable single-cycle pulses of toroidal topology, the exact solutions of Maxwell’s equations described by Hellwarth and Nouchi in 1996 and recently observed experimentally. Here we introduce an extended family of electromagnetic excitation, the supertoroidal electromagnetic pulses, in which the Hellwarth-Nouchi pulse is just the simplest member. The supertoroidal pulses exhibit skyrmionic structure of the electromagnetic fields, multiple singularities in the Poynting vector maps and fractal-like distributions of energy backflow. They are of interest for transient light-matter interactions, ultrafast optics, spectroscopy, and toroidal electrodynamics. Topology in electromagnetic fields can lead to a range of intriguing and unexpected phenomena. Here the authors describe a family of supertoroidal light pulses that exhibit skyrmionic topological structure flying in free space.
TL;DR: In this article, the authors introduce a new family of electromagnetic excitations of toroidal topology with increasing complexity in which the Hellwarth-Nouchi pulse is just the simplest member.
Abstract: Topological structures of electromagnetic fields could give access to nontrivial light-matter interactions and additional degrees of freedom for information and energy transfer. A characteristic example of such electromagnetic excitations are space-time non-separable single-cycle pulses, the exact solutions of Maxwell equation of toroidal topology predicted by Hellwarth and Nouchi in 1996 and recently observed experimentally. Here we introduce a new family of electromagnetic excitation of toroidal topology with increasing complexity in which the Hellwarth-Nouchi pulse is just the simplest member. The electromagnetic excitations of the new family can be parametrised by a single real number and exhibit skyrmionic structures of various orders. They feature multiple singularities in the electromagnetic and Poynting vector fields are accompanied by the fractal-like distributions of energy backflow. The generalized family of toroidal electromagnetic excitation with salient topologies are of interest for transient light-matter interactions, ultrafast optics, spectroscopy, and toroidal electrodynamics.
TL;DR: In this paper, the second harmonic of a second-order light with spatiotemporal orbital angular momentum (ST-OAM) pulses has been studied and the conservation of transverse OAM in a secondharmonic generation process is uncovered.
Abstract: Light with spatiotemporal orbital angular momentum (ST-OAM) is a recently discovered type of structured and localized electromagnetic field. This field carries characteristic space–time spiral phase structure and transverse intrinsic OAM. Here, we present the generation and characterization of the second harmonic of ST-OAM pulses. We uncover the conservation of transverse OAM in a second-harmonic generation process, where the space–time topological charge of the fundamental field is doubled along with the optical frequency. Our experiment thus suggests a general ST-OAM nonlinear scaling rule, analogous to that in conventional OAM of light. Furthermore, we observe that the topology of a second-harmonic ST-OAM pulse can be modified by complex spatiotemporal astigmatism, giving rise to multiple phase singularities separated in space and time. Our study opens a new route for nonlinear conversion and scaling of light carrying ST-OAM, with the potential for driving other secondary ST-OAM sources of electromagnetic fields and beyond. The second-harmonic spatiotemporal orbital angular momentum of an optical pulse and its space–time topological charge conservation during frequency doubling are experimentally observed, opening opportunities for nonlinear conversion and scaling of photons carrying spatiotemporal orbital angular momentum.
TL;DR: In this article, a quantum transition state theory (TSTT) was used to examine the coherent nature of adiabatic reactions in cavities and derive the cavity-induced changes in eigenfrequencies, zero-point energy, and quantum tunneling.
Abstract: The electromagnetic field in an optical cavity can dramatically modify and even control chemical reactivity via vibrational strong coupling (VSC). Since the typical vibration and cavity frequencies are considerably larger than thermal energy, it is essential to adopt a quantum description of cavity-catalyzed adiabatic chemical reactions. Using quantum transition state theory (TST), we examine the coherent nature of adiabatic reactions in cavities and derive the cavity-induced changes in eigenfrequencies, zero-point energy, and quantum tunneling. The resulting quantum TST calculation allows us to explain and predict the resonance effect (i.e., maximal kinetic modification via tuning the cavity frequency), collective effect (i.e., linear scaling with the molecular density), and selectivity (i.e., cavity-induced control of the branching ratio). The TST calculation is further supported by perturbative analysis of polariton normal modes, which not only provides physical insights to cavity-catalyzed chemical reactions but also presents a general approach to treat other VSC phenomena.
TL;DR: In this article, a cornucopia of potential astrophysical signatures and constraints on magnetically charged black holes of various masses are discussed, including limits on charges, location of stable orbits, and horizons in asymptotically flat and asythmically de Sitter backgrounds, bounds from galactic magnetic fields and dark matter measurements, characteristic electromagnetic fluxes, and telltale gravitational wave emissions during binary inspirals.
Abstract: We discuss a cornucopia of potential astrophysical signatures and constraints on magnetically charged black holes of various masses. As recently highlighted, being potentially viable astrophysical candidates with immense electromagnetic fields, they may be ideal windows to fundamental physics, electroweak symmetry restoration, and nonperturbative quantum field theoretic phenomena. We investigate various potential astrophysical pointers and bounds---including limits on charges, location of stable orbits, and horizons in asymptotically flat and asymptotically de Sitter backgrounds, bounds from galactic magnetic fields and dark matter measurements, characteristic electromagnetic fluxes, and tell-tale gravitational wave emissions during binary inspirals. Stable orbits around these objects hold an imprint of their nature and in the asymptotically de Sitter case, there is also a qualitatively new feature with the emergence of a stable outer orbit. We consider binary inspirals of both magnetic and neutral, and magnetic and magnetic, black hole pairs. The electromagnetic emissions and the gravitational waveform evolution, along with interblack hole separation, display distinct features. Many of the astrophysical signatures may be observationally glaring---for instance, even in regions of parameter space where no electroweak corona forms, owing to magnetic fields that are still many orders of magnitude larger than even magnetars, their consequent electromagnetic emissions will be spectacular during binary inspirals. While adding new results, our discussions also complement works in similar contexts, that have appeared recently in the literature.
TL;DR: In this article, an atomic-scale waveform sampling method based on scanning tunnelling microscopy is proposed to resolve femtosecond near field transients with sub-picosecond time resolution and sub-nanometre spatial resolution.
Abstract: Tailored nanostructures can confine electromagnetic waveforms in extremely sub-wavelength volumes, opening new avenues in lightwave sensing and control down to sub-molecular resolution. Atomic light–matter interaction depends critically on the absolute strength and the precise time evolution of the near field, which may be strongly influenced by quantum-mechanical effects. However, measuring atom-scale field transients has remained out of reach. Here we introduce quantitative atomic-scale waveform sampling in lightwave scanning tunnelling microscopy to resolve a tip-confined near-field transient. Our parameter-free calibration employs a single-molecule switch as an atomic-scale voltage standard. Although salient features of the far-to-near-field transfer follow classical electrodynamics, we develop a comprehensive understanding of the atomic-scale waveforms with time-dependent density functional theory. The simulations validate our calibration and confirm that single-electron tunnelling ensures minimal back-action of the measurement process on the electromagnetic fields. Our observations access an uncharted domain of nano-opto-electronics where local quantum dynamics determine femtosecond atomic near fields. Ultrafast lightwave sampling based on scanning tunnelling microscopy is developed to resolve near fields with sub-picosecond time resolution and sub-nanometre spatial resolution. Parameter-free quantitative measurement is achieved by using a single-molecule switch.
TL;DR: In this paper, the second-harmonic generation of light with spatiotemporal orbital angular momentum (ST-OAM) pulses was studied and the conservation of transverse OAM was uncovered.
Abstract: Light with spatiotemporal orbital angular momentum (ST-OAM) is a recently discovered type of structured and localized electromagnetic field. This field carries characteristic space-time spiral phase structure and transverse intrinsic OAM. In this work, we present the generation and characterization of the second-harmonic of ST-OAM pulses. We uncovered the conservation of transverse OAM in a second-harmonic generation process, where the space-time topological charge of the fundamental field is doubled along with the optical frequency. Our experiment thus suggests a general ST-OAM nonlinear scaling rule - analogous to that in conventional OAM of light. Furthermore, we observe that the topology of a second-harmonic ST-OAM pulse can be modified by complex spatiotemporal astigmatism, giving rise to multiple phase singularities separated in space and time. Our study opens a new route for nonlinear conversion and scaling of light carrying ST-OAM with the potential for driving other secondary ST-OAM sources of electromagnetic fields and beyond.
01 Jan 2021
TL;DR: In this paper, the authors present a useful insight into the comprehension of the configurations of electromagneto-vortex formation and their implications in the magnetic helicity and energy dissipation in magnetohydrodynamics.
Posted Content•
TL;DR: In this paper, a map of the theoretical tools available to tackle chemical applications of molecular polaritons at different scales is provided, and the authors draw attention to both the successes and the challenges still ahead in the theoretical description of polaritonic chemistry.
Abstract: Polaritonic chemistry exploits strong light-matter coupling between molecules and confined electromagnetic field modes to enable new chemical reactivities. In systems displaying this functionality, the choice of the cavity determines both the confinement of the electromagnetic field and the number of molecules that are involved in the process, whereas in wavelength-scale optical cavities light-matter interaction is ruled by collective effects, plasmonic subwavelength nanocavities allow even single molecules to reach strong coupling. Due to these very distinct situations, a multiscale theoretical toolbox is then required to explore the rich phenomenology of polaritonic chemistry. Within this framework, each component of the system (molecules and electromagnetic modes) needs to be treated in sufficient detail to obtain reliable results. Starting from the very general aspects of light-molecule interactions in typical experimental setups, we underline the basic concepts that should be taken into account when operating in this new area of research. Building on these considerations, we then provide a map of the theoretical tools already available to tackle chemical applications of molecular polaritons at different scales. Throughout the discussion, we draw attention to both the successes and the challenges still ahead in the theoretical description of polaritonic chemistry.
TL;DR: In this paper, the effect of a quench of one pancake coil on the electromagnetic-thermal-mechanical behaviors of an NI double-pancake (DP) coil in the self field and the high field was investigated.
Abstract: High-temperature superconducting double-pancake (DP) coils wound by the no-insulation (NI) approach have been proved to have a high thermal stability and a self-protecting ability. This paper mainly studies the effect of a quench of one pancake coil on the electromagnetic-thermal-mechanical behaviors of an NI DP coil in the self field and the high field. An electromagnetic-thermal coupling quench model is used to calculate the distributions of current, temperature and electromagnetic field in the coil, and then a three-dimensional homogeneous mechanical model is built to analyze the changes in strain and stress during a quench by considering the distributions of thermal strain and Lorentz force of the coil. The results indicate that the obvious increase in circumferential current and radial current density in the bottom pancake coil is induced by a quench of the top pancake coil due to the electromagnetic coupling effect in the self field and the high field, and that the DP coil still has a negative coil voltage during a quench in different fields. Although the bottom pancake coil has a large circumferential current, the mechanical deformation of the DP coil during a quench is mainly caused by the temperature rise in the self field. The thermal expansion of the top pancake coil has a remarkable effect on the mechanical behaviors of the bottom pancake coil. Moreover, the DP coil has the same temperature rise and mechanisms of bypass current in the self field and the high field. However, the mechanical deformation of the DP coil is based on the combined effects of temperature rise and Lorentz force in the high field. It can be found that the values of the hoop and axial stresses are affected by a large electromagnetic stress.
TL;DR: In this paper, the optimal communication involving large intelligent surfaces realized, for example, with metamaterials, as possible enabling technology for holographic communication is analyzed, and it is shown that traditional propagation models must be revised and that, when exploiting spherical wave propagation in the near-field region, new opportunities are opened, for e.g., in terms of feasible orthogonal communication channels.
Abstract: Holographic communication is intended as a holistic way to manipulate, with unprecedented flexibility, the electromagnetic field generated or sensed by an antenna. This is of particular interest when using large antennas at high frequency (e.g., at millimeter-wave or terahertz), whose operating condition may easily fall in the Fresnel region (radiating near-field), where the classical plane wave propagation assumption is no longer valid. This article analyzes the optimal communication involving large intelligent surfaces realized, for example, with metamaterials as possible enabling technology for holographic communication. It is shown that traditional propagation models must be revised and that, when exploiting spherical wave propagation in the near-field region, new opportunities are opened, for example, in terms of feasible orthogonal communication channels.
TL;DR: In this article, the innermost stable circular orbit (ISCO) radius of neutral and charged test particles was determined for axially symmetric magnetized black hole spacetime, and it was shown that the combined effect of black hole electric charge and magnetic field strongly affects the ISCO radius, thus shrinking its values.
Abstract: We investigate the dynamics of neutral and charged test particles around axially symmetric magnetized black hole spacetime. We consider its electromagnetic field in the black hole vicinity and study its impact on the dynamics of test particles. We determine the radius of the innermost stable circular orbit (ISCO) for neutral and charged test particles and show that the combined effect of black hole electric charge and magnetic field strongly affects the ISCO radius, thus shrinking its values. We also show that the ISCO radius of positively (negatively) charged particle initially gets increased (decreased) and then gets radically altered with an increase in the value of both black hole electric charge and test particle charge. It turns out that the repulsive (attractive) Coulomb force dominates over the Lorentz force arising from the black hole magnetic field. Typically, black hole rotation causes axially symmetric spacetime case. Similarly, it turns out that a magnetized black hole solution also causes axially symmetric spacetime as a consequence of the presence of magnetic field. We study a degeneracy for the value of the ISCO between the Kerr and the magnetized Reissner-Nordstr\"om black hole geometries and show that the combined effects of black hole charge and magnetic field can be mimicked by Kerr spacetime with the spin parameter up to $a/M\ensuremath{\approx}0.8$. Finally, we consider the center of mass energy of colliding particles and show that an increase in the values of black hole magnetic field and electric charge leads to high center of mass energy extracted by collision of two particles.
TL;DR: In this article, a variational direct method (VDM) is applied to construct the exact traveling wave solutions of the system of ion sound and Langmuir waves (SEISLWs), which is under the influence of the ponderomotive force caused by a nonlinear force experienced by a charged particle in an inhomogeneous oscillating electromagnetic field due to high-frequency field.
Abstract: In this paper, a novel and simple approach called the variational direct method (VDM) is applied to construct the exact traveling wave solutions of the system of ion sound and Langmuir waves (SEISLWs), which is under the influence of the ponderomotive force caused by a nonlinear force experienced by a charged particle in an inhomogeneous oscillating electromagnetic field due to high-frequency field. These exact solutions include the bright soliton, bright-like soliton, kinky-bright soliton, bright-dark soliton and periodic wave solutions, which are all presented through the numerical results in the form of 3-D plots. Obtained results show that the VDM is simple, straightforward and powerful, which is expected to open new perspectives for the traveling wave theory.
TL;DR: In this article, the Huygens' box is used to generate arbitrary electromagnetic waveforms inside a geometrical area enclosed by an active metasurface, where a region of space is enclosed by the active surface.
Abstract: This work investigates the generation of arbitrary electromagnetic waveforms inside a geometrical area enclosed by an active metasurface. We introduce the Huygens’ box, where a region of space is enclosed by an active Huygens’ metasurface. We show that, upon generating the necessary electric and magnetic currents, we can create any desired electromagnetic field inside Huygens’ box. Using this method, we demonstrate, through simulation and experiment, the generation of traveling plane waves, a standing plane wave, and a Bessel wave inside a metallic cavity. These waves are generated using the same (reconfigurable) metasurface by aptly controlling the electronic excitations. By linear superposition of these unconventional traveling-wave “modes,” we experimentally demonstrate, for the first time, a subwavelength superoscillation focal spot formed without involving evanescent EM waves and without an accompanying region of exorbitantly high waveform energy. The Huygens’ box brings controlled waveform generation to an unprecedented level, with far-reaching implications to imaging, wireless communication, and medical therapy.
20 Feb 2021
TL;DR: In this article, a stable individual second-order meron and antimeron appearing in an electromagnetic field was observed, which could help bring topologically robust room-temperature optical vector textures into the field of photonic information processing and storage.
Abstract: Multicomponent Bose–Einstein condensates, quantum Hall systems, and chiral magnetic materials display twists and knots in the continuous symmetries of their order parameters known as skyrmions. Originally discovered as solutions to the nonlinear sigma model in quantum field theory, these vectorial excitations are quantified by a topological winding number dictating their interactions and global properties of the host system. Here, we report the experimental observation of a stable individual second-order meron and antimeron appearing in an electromagnetic field. We realize these complex textures by confining light into a liquid-crystal-filled cavity that, through its anisotropic refractive index, provides an adjustable artificial photonic gauge field that couples the cavity photon motion to its polarization, resulting in the formation of these fundamental vectorial vortex states of light. Our observations could help bring topologically robust room-temperature optical vector textures into the field of photonic information processing and storage.
TL;DR: In this article, the primary wave and shear reflection and refraction during solid-liquid media under three thermoelastic theories and an electromagnetic field with an antenna array was investigated. But the authors focused only on the SV-wave and the p-wave.
Abstract: In this paper, we investigated the primary wave (p-wave) and shear (SV-wave) reflection and refraction during solid–liquid media under three thermoelastic theories and electromagnetic field with an...
TL;DR: In this paper, the authors optically trap a dielectric nanodumbbell in a linearly polarized laser field, where the dumbbell represents a nanomechanical librator.
Abstract: Rotational optomechanics strives to gain quantum control over mechanical rotors by harnessing the interaction of light and matter. We optically trap a dielectric nanodumbbell in a linearly polarized laser field, where the dumbbell represents a nanomechanical librator. Using measurement-based parametric feedback control in high vacuum, we cool this librator from room temperature to 240 mK and investigate its heating dynamics when released from feedback. We exclude collisions with residual gas molecules as well as classical laser noise as sources of heating. Our findings indicate that we observe the torque fluctuations arising from the zero-point fluctuations of the electromagnetic field.
TL;DR: In this paper, a scheme to compute electron wave functions in tightly focused laser beams by taking into account exactly the complex spacetime structure of the fields was proposed, based on the validity of the Wentzel-Kramers-Brillouin (WKB) approximation and the resulting wave functions, unlike previously proposed ones [Phys. Rev. Lett. 113, 040402 (2014), do not rely on approximations on the classical electron trajectory.
Abstract: Available laser technology is opening the possibility of testing QED experimentally in the so-called strong-field regime. This calls for developing theoretical tools to investigate strong-field QED processes in electromagnetic fields of complex spacetime structure. Here, we propose a scheme to compute electron wave functions in tightly focused laser beams by taking into account exactly the complex spacetime structure of the fields. The scheme is solely based on the validity of the Wentzel-Kramers-Brillouin (WKB) approximation and the resulting wave functions, unlike previously proposed ones [Phys. Rev. Lett. 113, 040402 (2014)], do not rely on approximations on the classical electron trajectory. Moreover, a consistent procedure is indicated to take into account higher-order quantum effects within the WKB approach depending on higher-and-higher powers of the Planck constant. In the case of a plane-wave background field the found wave functions exactly reduce to the Volkov states, which are then written in a new and fully quasiclassical form. Finally, by using the leading-order WKB wave functions to compute the probabilities of nonlinear Compton scattering and nonlinear Breit-Wheeler pair production, it is explicitly shown that, if additionally the energies of the charges are sufficiently large that the latter are not significantly deflected by the field, the corresponding Baier's formulas are exactly reproduced for an otherwise arbitrary classical electron/positron trajectory.
TL;DR: In this paper, the Hall current effect in homogeneous transversely isotropic magneto-thermoelastic (HTIMT) rotating medium with fractional-order heat transfer due to ramp-type heat is investigated.
Abstract: This investigation is focused on the study of Hall current effect in homogeneous transversely isotropic magneto-thermoelastic (HTIMT) rotating medium with fractional-order heat transfer due to ramp-type heat. Investigation of interaction between the strain, thermal and electromagnetic fields becomes a new area of research, which is called magneto-thermoelasticity because of its effective aspects in various domains of science and technology. Laplace and Fourier transform is used for solving field equations. The expressions of temperature, stress components, displacement components, and current density components are computed in the transformed domain. The effects of Hall current, rotation and fractional-order parameter at different values in HTIMT solid are represented graphically.