A multi-stable switchable metamaterial

The field of metamaterial research revolves around the idea of creating artificial media that interact with light in a way unknown from naturally occurring materials. This is commonly achieved by creating sub-wavelength lattices of electronic or plasmonic structures, so-called meta-atoms, that determine the interaction between light and metamaterial. One of the ultimate goals for these tailored media is the ability to control their properties in-situ which has led to a whole new branch of tunable and switchable metamaterials. Many of the present realizations rely on introducing microelectromechanical actuators or semiconductor elements into their meta-atom structures. Here we show that superconducting quantum interference devices (SQUIDs) can be used as fast, intrinsically switchable meta-atoms. We found that their intrinsic nonlinearity leads to simultaneously stable dynamic states, each of which is associated with a different value and sign of the magnetic susceptibility in the microwave domain. Moreover, we demonstrate that it is possible to switch between these states by applying a nanosecond long pulse in addition to the microwave probe signal. Apart from potential applications such as, for example, an all-optical metamaterial switch, these results suggest that multi-stability, which is a common feature in many nonlinear systems, can be utilized to create new types of meta-atoms

Russian Crime of the Past Decade: Is the Time of Illusions Over?

The purpose of the study is by analyzing the state and dynamics of crime in Russia over the past decade (2010-2020): 1) to identify the factors that influenced the criminal activity of the Russian population during this period; 2) determine the main directions of the then implemented state criminal policy; 3) assess its effectiveness. Research methods: method of summary and grouping of statistical observation materials, analysis of absolute and relative values (structure, intensity and dynamics), analysis of series of dynamics. The results of the study indicate that, since 2015, there has been a progressive increase in crime in Russia, due to unfavorable trends in the development of the socio-economic sphere. During this period, there was also a significant discrepancy between the data of official crime statistics and the real situation in the field of crime. This discrepancy was due to large-scale transformation processes taking place in the sphere of the state’s criminal policy. Accordingly, the decrease in the amount and level of official crime in Russia in 2016-2018 was a consequence of these processes, while the real crime continued to grow all these three years. However, the sharp increase in crimes against property committed through the use of information and communication technologies, which began in Russia several years ago, ultimately could not but be reflected in the data of official crime statistics – in the past two years, an increase in both the amount and the level of crime has been recorded in the state. Russian law enforcement agencies have so far shown their unwillingness to offer serious resistance to digital crime. Russian law enforcement agencies have so far demonstrated their unwillingness to offer serious resistance to digital crime. The situation is significantly complicated by the fact that a significant part of crimes in the sphere of information and communication technologies is committed by inmates of Russian prisons. This means that today, in addition to a strong external influence from the criminal environment, the country’s law enforcement system is also experiencing a powerful endogenous influence from the criminals who are already serving their sentences in prisons

Reactive trityl derivatives: stabilised carbocation mass-tags for life sciences applications

The rational design of novel triarylmethyl (trityl)-based mass tags (MT) for mass-spectrometric (MS) applications is described. We propose a "pKR+ rule" to correlate the stability of trityl carbocations with their MS performance: trityls with higher pKR+ values ionise and desorb better. Trityl blocks were synthesised that have high pKR+ values and are stable in conditions of MS analysis; these MTs can be ionised by matrix as well as irradiation with a 337 nm nitrogen laser. 13C-Labelled tags were prepared for MS quantitation applications. Moreover, the tags were equipped with a variety of functional groups allowing conjugation with different functionalities within (bio)molecules to enhance the MS characteristics of the latter. The MS behaviour of model polycationic trityl compounds with and without the matrix was studied to reveal that poly-trityl clusters are always singly charged under the (MA)LDI-TOF conditions. Several peptide-trityl conjugates were prepared and comparisons revealed a beneficial effect of trityl tags on the conjugate detection in MS. Trityl compounds containing para-methoxy- and dimethylamine groups, as well as a xanthene fragment, showed considerable enhancement in MS detection of model peptides; thus they are promising tools for proteomic applications. Dimethoxytrityl derivatives allow one to distinguish between Arg- and Lys-containing peptides. Maleimido trityl derivatives are suitable for the efficient derivatisation of thiol-containing peptides in pyridine

Fluxons in high-impedance long Josephson junctions

The dynamics of fluxons in long Josephson junctions is a well-known example of soliton physics and allows for studying highly nonlinear relativistic electrodynamics on a microscopic scale. Such fluxons are supercurrent vortices that can be accelerated by bias current up to the Swihart velocity, which is the characteristic velocity of electromagnetic waves in the junction. We experimentally demonstrate slowing down relativistic fluxons in Josephson junctions whose bulk superconducting electrodes are replaced by thin films of a high kinetic inductance superconductor. Here, the amount of magnetic flux carried by each supercurrent vortex is significantly smaller than the magnetic flux quantum $_0$. Our data show that the Swihart velocity is reduced by about one order of magnitude compared to conventional long Josephson junctions. At the same time, the characteristic impedance is increased by an order of magnitude, which makes these junctions suitable for a variety of applications in superconducting electronics

Fluxons in high-impedance long Josephson junctions

The dynamics of fluxons in long Josephson junctions is a well-known example of soliton physics and allows for studying highly nonlinear relativistic electrodynamics on a microscopic scale. Such fluxons are supercurrent vortices that can be accelerated by bias current up to the Swihart velocity, which is the characteristic velocity of electromagnetic waves in the junction. We experimentally demonstrate slowing down relativistic fluxons in Josephson junctions whose bulk superconducting electrodes are replaced by thin films of a high kinetic inductance superconductor. Here, the amount of magnetic flux carried by each supercurrent vortex is significantly smaller than the magnetic flux quantum $_0$. Our data show that the Swihart velocity is reduced by about one order of magnitude compared to conventional long Josephson junctions. At the same time, the characteristic impedance is increased by an order of magnitude, which makes these junctions suitable for a variety of applications in superconducting electronics

Ultrastrong photon-to-magnon coupling in multilayered heterostructures involving superconducting coherence via ferromagnetic layers

The critical step for future quantum industry demands realization of efficient information exchange between different-platform hybrid systems that can harvest advantages of distinct platforms. The major restraining factor for the progress in certain hybrids is weak coupling strength between the elemental particles. In particular, this restriction impedes a promising field of hybrid magnonics. In this work, we propose an approach for realization of on-chip hybrid magnonic systems with unprecedentedly strong coupling parameters. The approach is based on multilayered microstructures containing superconducting, insulating, and ferromagnetic layers with modified photon phase velocities and magnon eigenfrequencies. The enhanced coupling strength is provided by the radically reduced photon mode volume. Study of the microscopic mechanism of the photon-to-magnon coupling evidences formation of the long-range superconducting coherence via thick strong ferromagnetic layers in superconductor/ferromagnet/superconductor trilayer in the presence of magnetization precession. This discovery offers new opportunities in microwave superconducting spintronics for quantum technologies

Top and Bottom Spin Valves With Ni-Fe-Mn Antiferromagnetic Layer

Structure, magnetic and magnetoresistive properties of spin valves with Ni-Fe-Mn antiferromagnet as a pinning layer have been studied. A technique of fabrication of spin valves with an enhanced thermal stability and improved hysteretic characteristics has been elaborated

Top and Bottom Spin Valves With Ni-Fe-Mn Antiferromagnetic Layer

Structure, magnetic and magnetoresistive properties of spin valves with Ni-Fe-Mn antiferromagnet as a pinning layer have been studied. A technique of fabrication of spin valves with an enhanced thermal stability and improved hysteretic characteristics has been elaborated