arXiv subjects

Maxim Goryachev

Publications and source records attributed to Maxim Goryachev.

At least 73 records · Page 4Linked to original sources

arXiv2019

Electrodynamic improvements to the theory of magnetostatic modes in ferrimagnetic spheres and their applications to saturation magnetization measurements

Electrodynamic theory applied to the analysis of TEn0p mode resonances in ferromagnetic spheres placed either in metallic cavities or in the free space is compared with Walker-Fletcher's theory of so-called magnetostatic modes. The influence of the diameter of the sample, its permittivity and the permittivity of the surrounding media on the resonance frequencies of a few modes is analyzed. It is shown that the dominant resonances are essentially related either to negative values of the diagonal component of the permeability tensor or, for clockwise circularly polarized magnetic fields, to negative effective permeability. The electrodynamic theory is used to determine the saturation magnetization (Ms) from measured TEn01 frequency differences. Measurements on different samples confirmed that Ms can be determined using an electrodynamic approach with uncertainties of the order of 2% regardless of sample sizes, metal enclosures or static magnetic field values.

physics.app-ph↗

arXiv2019

Experimental Implementation of a Large Scale Multipost Re-Entrant Array

We demonstrate possibilities of a large scale multi-post re-entrant cavity with two case studies implemented with the same physical structure. The first demonstration implements two discrete Fabry-P{é}rot cavities crossing at the centre. The configuration allows the control not only of the resonance frequencies, but also a whole band gap and transmission band of frequencies between the directly excited diagonal and a higher frequency band. The second experiment demonstrates appearance of discrete Whispering Gallery Modes on a circle of re-entrant post. With the introduction of an artificial "scatterer", we demonstrate control over the doublet mode splitting.

physics.ins-det↗

arXiv2019

Broadening Frequency Range of a Ferromagnetic Axion Haloscope with Strongly Coupled Cavity-Magnon Polaritons

With the axion being a prime candidate for dark matter, there has been some recent interest in direct detection through a so called `Ferromagnetic haloscope.' Such devices exploit the coupling between axions and electrons in the form of collective spin excitations of magnetic materials with the readout through a microwave cavity. Here, we present a new, general, theoretical treatment of such experiments in a Hamiltonian formulation for strongly coupled magnons and photons, which hybridise as cavity-magnon polaritons. Such strongly coupled systems have an extended measurable dispersive regime. Thus, we extend the analysis and operation of such experiments into the dispersive regime, which allows any ferromagnetic haloscope to achieve improved bandwidth with respect to the axion mass parameter space. This experiment was implemented in a cryogenic setup, and initial search results are presented setting laboratory limits on the axion-electron coupling strength of $g_{aee}>3.7\times10^{-9}$ in the range $33.79~μ$eV$< m_a<33.94~μ$eV with $95\%$ confidence. The potential bandwidth of the Ferromagnetic haloscope was calculated to be in two bands, the first of about $1$GHz around $8.24$GHz (or $4.1~μ$eV mass range around $34.1~μ$eV) and the second of about $1.6$GHz around $10$GHz ($6.6~μ$eV mass range around $41.4~μ$eV). Frequency tuning may also be easily achieved via an external magnetic field which changes the ferromagnetic resonant frequency with respect to the cavity frequency. The requirements necessary for future improvements to reach the DFSZ axion model band are discussed in the paper.

physics.ins-det↗

arXiv2018

Probing Dark Universe with Exceptional Points

It is demonstrated that detection of putative particles such as paraphotons and axions constituting the dark sector of the universe can be reduced to detection of extremely weak links or couplings between cavities and modes. This method allows utilisation of extremely sensitive frequency metrology methods that are not limited by traditional requirements on ultra low temperatures, strong magnetic fields and sophisticated superconducting technology. We show that exceptional points in the eigenmode structure of coupled modes may be used to boost the sensitivity of dark matter mediated weak links. We find observables that are proportional to fractional powers of fundamental coupling constants. Particularly, in the case of axion detection, it is demonstrated that resonance frequency scaling with $\sim \sqrt{g_{aγγ}θ}$ and $\sim \sqrt[3]{g_{aγγ}θ}$ dependencies can be realised in a ternary photonic cavity system, which is beneficial as these coupling constants are extremely small.

hep-ex↗

arXiv2018

Low temperature properties of whispering gallery modes in isotopically pure silicon 28

Whispering Gallery (WG) mode resonators have been machined from a boule of single-crystal isotopically pure silicon-28. Before machining, the as-grown rod was measured in a cavity, with the best Bragg confined modes exhibiting microwave $Q$-factors on the order of a million for frequencies between 10 and 15 GHz. After machining the rod into smaller cylindrical WG mode resonators, the frequencies of the fundamental mode families were used to determine the relative permittivity of the material to be $11.488\pm0.024$ near 4 K, with the precision limited only by the dimensional accuracy of the resonator. However, the Q-factors were degraded by the machining to below $4\times10^4$. Raman spectroscopy was used to optimize post-machining surface treatments to restore high $Q$-factors. This is an enabling step for the use of such resonators for hybrid quantum systems and frequency conversion applications, as silicon-28 also has very low phonon losses, can host very narrow linewidth spin ensembles and is a material commonly used in optical applications.

cond-mat.mtrl-sci↗

arXiv2018

Broadband Axion Dark Matter Haloscopes via Electric Sensing

The mass of axion dark matter is only weakly bounded by cosmological observations, necessitating a variety of detection techniques over several orders of magnitude of mass ranges. Axions haloscopes based on resonant cavities have become the current standard to search for dark matter axions. Such structures are inherently narrowband and for low masses the volume of the required cavity becomes prohibitively large. Broadband low-mass detectors have already been proposed using inductive magnetometer sensors and a gapped toroidal solenoid magnet. In this work we propose an alternative, which uses electric sensors in a conventional solenoidal magnet aligned in the laboratory z-axis, as implemented in standard haloscope experiments. In the presence of the DC magnetic field, the inverse Primakoff effect causes a time varying permanent electric vacuum polarization in the z-direction to oscillate at the axion Compton frequency, which induces an oscillating electromotive force. We propose non-resonant techniques to detect this oscillating elctromotive force by implementing a capacitive sensor or an electric dipole antenna coupled to a low noise amplifier. We present the first experimental results and discuss the foundations and potential of this proposal. Preliminary results constrain $g_{aγγ} >\sim2.35\times10^{-12}$ $\text{GeV}^{-1}$ in the mass range of $2.08\times10^{-11}$ to $2.2\times10^{-11}$ eV, and demonstrate potential sensitivity to axion-like dark matter with masses in the range of $10^{-12}$ to $10^{-8}$ eV.

physics.ins-det↗

arXiv2018

Next Generation of Phonon Tests of Lorentz Invariance using Quartz BAW Resonators

We demonstrate technological improvements in phonon sector tests of Lorentz Invariance that implement quartz Bulk Acoustic Wave oscillators. In this experiment, room temperature oscillators with state-of-the-art phase noise are continuously compared on a platform that rotates at a rate of order a cycle per second. The discussion is focused on improvements in noise measurement techniques, data acquisition and data processing. Preliminary results of the second generation of such tests are given, and indicate that SME coefficients in the matter sector can be measured at a precision of order $10^{-16}$ GeV after taking a years worth of data. This is equivalent to an improvement of two orders of magnitude over the prior acoustic phonon sector experiment.

physics.ins-det↗

arXiv2018

Inducing Strong Non-Linearities in a Phonon Trapping Quartz Bulk Acoustic Wave Resonator Coupled to a Superconducting Quantum Interference Device

A quartz Bulk Acoustic Wave resonator is designed to coherently trap phonons in a way that they are well confined and immune to suspension losses so they exhibit extremely high acoustic $Q$-factors at low temperature, with $Q\times f$ products of order $10^{18}$ Hz. In this work we couple such a resonator to a SQUID amplifier and investigate effects in the strong signal regime. Both parallel and series connection topologies of the system are investigated. The study reveals significant non-Duffing response that is associated with the nonlinear characteristics of Josephson junctions. The nonlinearity provides quasi-periodic structure of the spectrum in both incident power and frequency. The result gives an insight into the open loop behaviour of a future Cryogenic Quartz Oscillator in the strong signal regime.

physics.ins-det↗

arXiv2018

Cavity Magnon Polaritons with Lithium Ferrite and 3D Microwave Resonators at milli-Kelvin Temperatures

Single crystal Lithium Ferrite (LiFe) spheres of sub-mm dimension are examined at mK temperatures, microwave frequencies and variable DC magnetic field, for use in hybrid quantum systems and condensed matter and fundamental physics experiments. Strong coupling regimes of the photon-magnon interaction (cavity magnon polariton quasi-particles) were observed with coupling strength of up to 250 MHz at 9.5 GHz (2.6\%) with magnon linewidths of order 4 MHz (with potential improvement to sub-MHz values). We show that the photon-magnon coupling can be significantly improved and exceed that of the widely used Yttrium Iron Garnet crystal, due to the small unit cell of LiFe, allowing twice more spins per unit volume. Magnon mode softening was observed at low DC fields and combined with the normal Zeeman effect creates magnon spin wave modes that are insensitive to first order order magnetic field fluctuations. This effect is observed in the Kittel mode at 5.5 GHz (and another higher order mode at 6.5 GHz) with a DC magnetic field close to 0.19 Tesla. We show that if the cavity is tuned close to this frequency, the magnon polariton particles exhibit an enhanced range of strong coupling and insensitivity to magnetic field fluctuations with both first order and second order insensitivity to magnetic field as a function of frequency (double magic point clock transition), which could potentially be exploited in cavity QED experiments.

cond-mat.str-el↗

arXiv2017

Strong Coupling of 3D Cavity Photons to Travelling Magnons At Low Temperatures

We demonstrate strong coupling between travelling magnons in an Yttrium Iron Garnet film and 3D microwave cavity photons at milli-Kelvin temperatures. The coupling strength of $350$MHz or $7.3$\% of resonance frequency is observed. The magnonic subsystem is represented by the Damon-Eshbach magnetostatic surface wave with a distribution of wave numbers giving the linewidth of 15MHz. The ways to improve this parameter are discussed. The energy gap in the spectrum given by the Zeeman energy and the shape-anisotropy energy in the film geometry give rise to a significant asymmetry of the double peak structure of the photon-magnon avoided level crossing. A structure of two parallel YIG films is investigated using the same re-entrant magnetostatic surface wave transducer revealing a higher order magnon modes existing in both films. Combination of a multi-post re-entrant cavity and multiple films is a potential base for engineering both magnon and photon spectra.

cond-mat.mtrl-sci↗

arXiv2017

The ORGAN Experiment: An axion haloscope above 15 GHz

We present first results and future plans for the Oscillating Resonant Group AxioN (ORGAN) experiment, a microwave cavity axion haloscope situated in Perth, Western Australia designed to probe for high mass axions motivated by several theoretical models. The first stage focuses around 26.6 GHz in order to directly test a claimed result, which suggests axions exist at the corresponding mass of $110~μ$eV. Later stages will move to a wider scan range of 15-50 GHz ($60-210~μ$eV). We present the results of the pathfinding run, which sets a limit on $g_{aγγ}$ of $2.02\times 10^{-12} $eV$^{-1}$ at 26.531 GHz, or 110~$μ$eV, in a span of 2.5 neV (shaped by the Lorentzian resonance) with $90 \%$ confidence. Furthermore, we outline the current design and future strategies to eventually attain the sensitivity to search for well known axion models over the wider mass range.

physics.ins-det↗

arXiv2017

Axion Detection with Cavity Arrays

Using eigenmode analysis and full 3D FEM modelling, we demonstrate that a closed cavity built of an array of elementary harmonic oscillators with negative mutual couplings exhibits a dispersion curve with lower order modes corresponding to higher frequencies. Such cavity arrays may help to achieve large mode volumes for boosting sensitivity of the axion searches, where the mode volume for the composed array scales proportional to the number of elements, but the frequency remains constant. The negatively coupled cavity array is demonstrated with magnetically coupling coils, where the sign of next-neighbour coupling (controlled with their chirality) sets the dispersion curve properties of the resonator array medium. Furthermore, we show that similar effects can be achieved using only positively coupled cavities of different frequencies assembled in periodic cells. This principle is demonstrated for the multi-post re-entrant system, which can be realised with an array of straight metallic rods organised in chiral structures.

physics.ins-det↗

arXiv2017

Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and single photon energy

Electromagnetic properties of single crystal terbium gallium garnet (TGG) are characterised from room down to millikelvin temperatures using the whispering gallery mode method. Microwave spectroscopy is performed at low powers equivalent to a few photons in energy and conducted as functions of the magnetic field and temperature. A phase transition is detected close to the temperature of 3.5 K. This is observed for multiple whispering gallery modes causing an abrupt negative frequency shift and a change in transmission due to extra losses in the new phase caused by a change in complex magnetic susceptibility.

cond-mat.mtrl-sci↗

arXiv2017

Indirect Methods to Control Population Distribution in a Large Spin System

We demonstrate how a large spin system ($S=7/2$) with the ground and the first excited state separated by a seven photon transition exhibit non equilibrium thermodynamic properties and how the population distribution may be manipulated using coupling between energy levels. The first method involves non-adiabatic passage through an avoided level crossing controlled with an external DC magnetic field and the resulting Landau Zener transition. The second method is based on external cavity pumping to a higher energy state hybridised with another state that is two single photon transitions away from the ground state. The results are confirmed experimentally with Gd$^{3+}$ impurity ion ensemble in a YVO$_{4}$ crystal cooled to 20 mK, which also acts as a microwave photonic whispering gallery mode resonator. Extremely long life times are observed due to large number of photons required for the transition between the ground and the first excited states.

quant-ph↗

arXiv2016

Reconfigurable Microwave Photonic Topological Insulator

Using full 3D finite element simulation and underlining Hamiltonian models, we demonstrate reconfigurable photonic analogues of topological insulators on a regular lattice of tunable posts in a re-entrant 3D lumped element type system. The tunability allows dynamical {\it in-situ} change of media chirality and other properties via alteration of the same parameter for all posts, and as a result, great flexibility in choice of bulk/edge configurations. Additionally, one way photon transport without an external magnetic field is demonstrated. The ideas are illustrated by using both full finite element simulation as well as simplified harmonic oscillator models. Dynamical reconfigurability of the proposed systems paves the way to a new class of systems that can be employed for random access, topological signal processing and sensing.

physics.ins-det↗

arXiv2016

Determination of Low Loss in Isotopically Pure Single Crystal $^{28}$Si at Low Temperatures and Single Microwave Photon Energy

The low dielectric losses of an isotropically pure single crystal $^{28}$Si sample were determined at a temperature of 20 mK and at powers equivalent to that of a single photon. Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order $2\times10^6$ (dielectric loss $\sim 5\times10^{-7}$) at high powers, degrading to $7\times10^5$ (dielectric loss $\sim 1.4\times10^{-6}$) at single photon energy. A very low-loss narrow line width paramagnetic spin flip transition was detected with extreme sensitivity in $^{28}$Si, with very small concentration below $10^{11}$~cm$^{-3}$ (less than 10 parts per trillion) and g-factor of $1.995\pm0.008$. Such determination was only possible due to the low dielectric photonic losses combined with the long lifetime of the spin transition (low magnetic loss), which enhances the magnetic AC susceptibility. Such low photonic loss at single photon energy combined with the narrow line width of the spin ensemble, indicate that single crystal $^{28}$Si could be an important crystal for future cavity QED experiments.

cond-mat.mes-hall↗

arXiv2016

A 3D Printed Superconducting Aluminium Microwave Cavity

3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals in particular has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Whilst many techniques can be used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable to the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared to Al-6061, which has between 0.4 to 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

physics.ins-det↗

arXiv2016

A new method of probing mechanical losses of coatings at cryogenic temperatures

A new method of probing mechanical losses and comparing the corresponding deposition processes of metallic and dielectric coatings in 1-100 MHz frequency range and cryogenic temperatures is presented. The method is based on the use of extremely high-quality quartz acoustic cavities whose internal losses are orders of magnitude lower than any available coatings nowadays. The approach is demonstrated for Chromium, Chromium/Gold and a multilayer tantala/silica coatings. The ${\rm Ta}_2{\rm O}_5/{\rm Si}{\rm O}_2$ coating has been found to exhibit a loss angle lower than $1.6\times10^{-5}$ near 30 {\rm MHz} at 4 {\rm K}. The results are compared to the previous measurements.

physics.ins-det↗