arXiv subjects

Nikita A. Olekhno

Publications and source records attributed to Nikita A. Olekhno.

14 recordsLinked to original sources

arXiv2026

A rechargeable AA battery supporting Qi wireless charging

Wireless power transfer is one of the key drivers in modern consumer electronics, as it allows one to enhance the convenience and usability of many devices. However, in most cases, wireless charging is accessible only to devices with incorporated receivers or at least to gadgets with standard charging connectors, such as USB Type-C, that allow to attach an external receiver. We propose a rechargeable battery that has the size and output voltage of a standard AA battery but supports wireless power transfer from charging stations of the widely used Qi standard. The proposed design uses a series resonant circuit with a curved receiving coil, as well as load modulation using detuning capacitors switched by a microcontroller unit to implement a receiver compatible with the Qi Baseline protocol. It also utilizes a number of DC-DC converters to store energy in a Li-ion cell and convert it to the 1.5 V voltage level. Our design is supported by numerical simulations of magnetic field distributions and scattering parameters of the introduced battery coupled to a planar transmitting coil. The performance of the proposed battery has been studied experimentally, including measurements of the maximal distance between the battery and a charging station that allows wireless charging at various rotation angles and the charge curve. The developed battery design facilitates the addition of wireless charging functionality to a wide range of electronic devices in a universal way.

physics.app-ph↗

arXiv2026

Higher-order topological metasurface based on split-ring resonators with dipole-quadrupole couplings

Photonic higher-order topological insulators (HOTI) are characterized by a hierarchy of topologically-protected states with different dimensionalities, making them especially interesting for potential applications that combine strong localization of electromagnetic fields and their robust waveguiding. However, their practical implementation often requires expensive processing techniques and is limited by accessible material parameters. In this paper, we demonstrate that a radio-frequency photonic HOTI can be implemented as a metasurface composed of split-ring resonators with couplings between dipole and quadrupole modes. We verify, by numerical simulations and experimentally at frequencies of 1.5-1.7 GHz, that a proposed metasurface supports corner- and edge-localized states. Our results reveal a scalable and easily reconfigurable GHz-range platform that employs printed circuit board technology, thus making crucial steps required for further experimental studies of photonic HOTI and the development of their microwave applications.

cond-mat.mes-hall↗

arXiv2026

Theoretical description of interface states in a tetragonal lattice of bianisotropic resonators

In the present paper, we construct a theoretical description of a three-dimensional photonic structure in the form of a tetragonal lattice of bianisotropic resonators applying a dyadic Green's function approach. By representing the resonators as point electric and magnetic dipoles, we obtain the Bloch Hamiltonians for the approximations considering the interactions between the nearest, next-nearest, and next-to-next-nearest resonators, and construct the corresponding real-space tight-binding models. We analyze the band diagrams, spatial structure of the eigenmodes, and their localization, revealing quadratic degeneracies in the vicinity of high-symmetry points in the absence of bianisotropy and the emergence of in-gap states localized at a domain wall upon the introduction of bianisotropy. Finally, we compare the theoretical results with full-wave numerical simulations for an array of bianisotropic resonators.

physics.optics↗

arXiv2025

Swarmodroid & AMPy: Reconfigurable Bristle-Bots and Software Package for Robotic Active Matter Studies

Large assemblies of extremely simple robots capable only of basic motion activities (like propelling forward or self-rotating) are often applied to study swarming behavior or implement various phenomena characteristic of active matter composed of non-equilibrium particles that convert their energy to a directed motion. As a result, a great abundance of compact swarm robots have been developed. The simplest are bristle-bots that self-propel via converting their vibration with the help of elastic bristles. However, many platforms are optimized for a certain class of studies, are not always made open-source, or have limited customization potential. To address these issues, we develop the open-source Swarmodroid 1.0 platform based on bristle-bots with reconfigurable 3D printed bodies and simple electronics that possess external control of motion velocity and demonstrate basic capabilities of trajectory adjustment. Then, we perform a detailed analysis of individual Swarmodroids' motion characteristics and their kinematics. In addition, we introduce the AMPy software package in Python that features OpenCV-based extraction of robotic swarm kinematics accompanied by the evaluation of key physical quantities describing the collective dynamics. Finally, we discuss potential applications as well as further directions for fundamental studies and Swarmodroid 1.0 platform development.

cond-mat.soft↗

arXiv2025

Micellization in active matter of asymmetric self-propelled particles: Experiments

Active matter composed of self-propelled particles features fascinating self-organization phenomena, spanning from motility-induced phase separation to phototaxis to topological excitations depending on the nature and parameters of the system. In the present paper, we consider micelle formation by active particles with a broken symmetry having a circular back and a sharpened nose toward which the particles accelerate. As we demonstrate in experiments with robotic swarms, such particles can either remain in the isotropic phase or form micelles depending on the location of their center of inertia, in accordance with a recent theoretical proposal [T. Kruglov and A. Borisov, Presentations and Videos to 7th Edition of the International Conference on Particle-based Methods (2021), Vol. CT07, p. 2]. Such a behavior is observed for both nonchiral particles moving linearly and placed in a parabolic potential and for chiral particles moving along circular trajectories on a flat surface. By performing experiments with single robots and two-robot collisions, we unveil that the observed emergence of micellization associated with shifting robots' center of inertia towards their noses is governed by at least two-particle effects, in particular, by a difference in the formation of stable two-robot clusters. Finally, we consider the dependence of micelle lifetime and formation probability as well as two-robot collisions on friction between the lateral surfaces of the robots. Crucially, the predicted micellization does not involve any solvation shells that give rise to the micellization of surfactants but is instead driven by an interplay of activity and particle shape asymmetry.

cond-mat.soft↗

arXiv2025

Topological edge states in all-dielectric square-lattice arrays of bianisotropic microwave resonators

We demonstrate that a bianisotropic response associated with a broken mirror symmetry of a dielectric resonator allows opening a band gap in simple square lattice arrays of such resonators. Realizing the proposed system as an array of high-index ceramic resonators working at GHz frequencies, we numerically and experimentally demonstrate the presence of topological edge states at the interface between two domains with opposite orientations of the bianisotropic resonators, as well as at the boundary between a single domain and free space. For both cases, we experimentally characterize the dispersion of edge states, and we examine their propagation along sharp bends, their resilience to various types of geometrical defects, and a spin-momentum-locked unidirectional propagation in the case of circularly polarized excitation. Also, we develop a theoretical model based on a Green's function approach that describes the square lattice of resonators and features quadratic degeneracies in the vicinity of $Γ$ and $M$ high-symmetry points that are removed upon the introduction of bianisotropy, and apply this model to evaluate Berry curvature. The considered design opens possibilities in the construction of optical and microwave structures simultaneously featuring topological edge states at the interfaces between distinct resonator domains or a resonator domain and free space.

physics.optics↗

arXiv2023

Wireless power transfer in magnetic resonance imaging at a higher-order mode of a birdcage coil

Magnetic resonance imaging (MRI) is a crucial tool for medical visualization. In many cases, performing a scanning procedure requires the use of additional equipment, which can be powered by wires as well as via wireless power transfer (WPT) or wireless energy harvesting. In this Letter, we propose a novel scheme for WPT that uses a higher-order mode of the MRI scanner's birdcage coil for energy transmission. In contrast to the existing WPT solutions, our approach does not require additional transmitting coils. Compared to the energy harvesting, the proposed method allows supplying significantly more power. We perform numerical simulations demonstrating that one can use the fundamental mode of the birdcage coil to perform a scanning procedure while transmitting the energy to the receiver at a higher-order mode without any interference with the scanning signal or violation of safety constraints, as guaranteed by the mode structure of the birdcage. Also, we evaluate the specific absorption rate along with the energy transfer efficiency and verify our numerical model by a direct comparison with an experimental setup featuring a birdcage coil of a 1.5T MRI scanner.

physics.app-ph↗

arXiv2022

Application of topological edge states in magnetic resonance imaging

Topological edge states in electromagnetic systems feature a set of attracting fundamental properties and unveil prospective applications based on disorder robustness and tailored localization. Despite active efforts in implementing topologically-protected waveguides in 2D photonic systems, applications of 1D topological systems remain almost uncharted. This letter demonstrates that topological edge modes can be realized in metamaterial-inspired volumetric resonators with a practical application in clinical magnetic resonance imaging (MRI). Performing numerical simulations and experiments with a 1.5 T MR scanner, we reconstruct the associated topological edge mode profiles and demonstrate their feasibility for sensitivity enhancement of conventional radiofrequency coils.

physics.app-ph↗

arXiv2021

Electric circuit emulation of topological transitions driven by quantum statistics

Topological phases exhibit a plethora of striking phenomena including disorder-robust localization and propagation of waves of various nature. Of special interest are the transitions between the different topological phases which are typically controlled by the external parameters. In contrast, in this Letter, we predict the topological transition in the two-particle interacting system driven by the particles' quantum statistics. As a toy model, we investigate an extended one-dimensional Hubbard model with two anyonic excitations obeying fractional quantum statistics in-between bosons and fermions. As we demonstrate, the interplay of two-particle interactions and tunneling processes enables topological edge states of anyon pairs whose existence and localization at one or another edge of the one-dimensional system is governed by the quantum statistics of particles. Since a direct realization of the proposed system is challenging, we develop a rigorous method to emulate the eigenmodes and eigenenergies of anyon pairs with resonant electric circuits.

quant-ph↗

arXiv2021

Generating ${\rm N00N}$-states of surface plasmon-polariton pairs with a nanoparticle

We consider a generation of two-particle quantum states in the process of spontaneous parametric down-conversion of light by a dielectric nanoparticle with $χ^{(2)}$ response. As a particular example, we study the generation of surface plasmon-polariton pairs with a ${\rm GaAs}$ nanoparticle located at the silver-air interface. We show that for certain excitation geometries, ${\rm N00N}$-states of surface plasmon-polariton pairs could be obtained. The effect can be physically interpreted as a result of quantum interference between pairs of induced sources, each emitting either signal or idler plasmon. We then relate the resulting ${\rm N00N}$-pattern to the general symmetry properties of dyadic Green's function of a dipole emitter exciting surface waves. It renders the considered effect as a general way towards a robust generation of ${\rm N00N}$-states of surface waves using spontaneous parametric down-conversion in $χ^{(2)}$ nanoparticles.

physics.optics↗

arXiv2021

Higher-order topological states mediated by long-range coupling in $D_4$-symmetric lattices

Topological physics opens a door towards flexible routing and resilient localization of waves of various nature. Recently proposed higher-order topological insulators provide advanced control over wave localization in the structures of different dimensionality. In many cases, the formation of such higher-order topological phases is governed by the lattice symmetries, with kagome and breathing honeycomb lattices being prominent examples. Here, we design and experimentally realize the resonant electric circuit with $D_4$ symmetry and additional next-nearest-neighbor couplings. As we prove, a coupling of the distant neighbors gives rise to an in-gap corner state. Retrieving the associated invariant directly from the experiment, we demonstrate the topological nature of the designed system, revealing the role of long-range interactions in the formation of topological phases. Our results thus highlight the distinctions between tight-binding systems and their photonic counterparts with long-range couplings.

cond-mat.mes-hall↗

arXiv2020

Quantum Hall phase emerging in an array of atoms interacting with photons

Topological quantum phases underpin many concepts of modern physics. While the existence of disorder-immune topological edge states of electrons usually requires magnetic fields, direct effects of magnetic field on light are very weak. As a result, demonstrations of topological states of photons employ synthetic fields engineered in special complex structures or external time-dependent modulations. Here, we reveal that the quantum Hall phase with topological edge states, spectral Landau levels and Hofstadter butterfly can emerge in a simple quantum system, where topological order arises solely from interactions without any fine-tuning. Such systems, arrays of two-level atoms (qubits) coupled to light being described by the classical Dicke model, have recently been realized in experiments with cold atoms and superconducting qubits. We believe that our finding will open new horizons in several disciplines including quantum physics, many-body physics, and nonlinear topological photonics, and it will set an important reference point for experiments on qubit arrays and quantum simulators.

quant-ph↗

arXiv2020

Topological edge states of interacting photon pairs emulated in a topolectrical circuit

Topological physics opens up a plethora of exciting phenomena allowing to engineer disorder-robust unidirectional flows of light. Recent advances in topological protection of electromagnetic waves suggest that even richer functionalities can be achieved by realizing topological states of quantum light. This area, however, remains largely uncharted due to the number of experimental challenges. Here, we take an alternative route and design a classical structure based on topolectrical circuits which serves as a simulator of a quantum-optical one-dimensional system featuring the topological state of two photons induced by the effective photon-photon interaction. Employing the correspondence between the eigenstates of the original problem and circuit modes, we use the designed simulator to extract the frequencies of bulk and edge two-photon bound states and evaluate the topological invariant directly from the measurements. Furthermore, we perform a reconstruction of the two-photon probability distribution for the topological state associated with one of the circuit eigenmodes.

cond-mat.mes-hall↗

arXiv2019

Photon-mediated localization in two-level qubit arrays

We predict the existence of a novel interaction-induced spatial localization in a periodic array of qubits coupled to a waveguide. This localization can be described as a quantum analogue of a self-induced optical lattice between two indistinguishable photons, where one photon creates a standing wave that traps the other photon. The localization is caused by the interplay between on-site repulsion due to the photon blockade and the waveguide-mediated long-range coupling between the qubits.

quant-ph↗