Dmitry R. Gulevich

Surface plasma waves across the layers of intrinsic Josephson junctions

We predict surface electromagnetic waves propagating across the layers of intrinsic Josephson junctions. We find the spectrum of the surface waves, and study the distribution of the electromagnetic field inside and outside the superconductor. The profile of the amplitude oscillations of the electric-field component of such waves is peculiar: initially, it increases toward the center of the superconductor and, after reaching a crossover point, decreases exponentially.

New phenomena in long Josephson junctions

We describe new phenomena arising in long and extended Josephson junctions associated with the two-dimensional character of these junctions. A vortex in such junctions has additional degrees of freedom related to its length. We investigate the behaviour of a Josephson vortex in curved waveguides. As a result we have proposed how to increase transmission properties of a curved waveguide. Moreover, there may arise a flux cloning phenomenon. In this phenomenon the vortex may split into two or more new vortices at the special T, Y or any multiple shaped junction. We describe a series of new devices, the operation of which is based on flux cloning.

Perturbation theory for localized solutions of the sine-Gordon equation : Decay of a breather and pinning by a microresistor

We develop a perturbation theory that describes bound states of solitons localized in a confined area. External forces and the influence of inhomogeneities are taken into account as perturbations to exact solutions of the sine-Gordon equation. We have investigated two special cases: a fluxon trapped by a microresistor and decay of a breather under dissipation. We have also carried out numerical simulations with the dissipative sine-Gordon equation and made a comparison with the McLaughlin-Scott theory. A significant distinction between the McLaughlin-Scott calculation for a breather decay and our numerical result indicates that the history dependence of the breather evolution cannot be neglected even for a small damping parameter.

Shape Waves in 2D Josephson Junctions: Exact Solutions and Time Dilation

We predict a new class of excitations propagating along a Josephson vortex in two-dimensional Josephson junctions. These excitations are associated with the distortion of a Josephson vortex line and have an analogy with shear waves in solid mechanics. Their shapes can have an arbitrary profile, which is retained when propagating. We derive a universal analytical expression for the energy of arbitrary shape excitations, investigate their influence on the dynamics of a vortex line, and discuss conditions where such excitations can be created. Finally, we show that such excitations play the role of a clock for a relativistically moving Josephson vortex and suggest an experiment to measure a time dilation effect analogous to that in special relativity.

Fluxon collider for multiple fluxon–antifluxon collisions

We describe a device for generation and trapping of fluxon?antifluxon (FA) pairs in a long annular Josephson junction. The trapped fluxons and antifluxons experience multiple collisions and eventually decay into plasmons. We analyse the energy dissipation in the system and find the criteria for trapping of the FA pair. We describe a possible experiment for realization of multiple FA trapping and formation of a FA plasma. Similar to vortex liquids discussed recently by Anderson it might be a good candidate for another vortex liquid. The proposed device can be made of niobium or high temperature superconductors.

Light-Induced Anisotropic Skyrmion and Stripe Phases in a Rashba Ferromagnet

An external off-resonant pumping is proposed as a tool to control the Dzyaloshinskii-Moriya interaction (DMI) in ferromagnetic layers with strong spin-orbit coupling. Combining theoretical analysis with numerical simulations for an s-d-like model, we demonstrate that linearly polarized off-resonant light may help stabilize novel noncollinear magnetic phases by inducing a strong anisotropy of the DMI. We also investigate how with the application of electromagnetic pumping one can control the stability, shape, and size of individual Skyrmions to make them suitable for potential applications.

Hybrid surface waves in two-dimensional Rashba-Dresselhaus materials

We address the electromagnetic properties of two-dimensional electron gas confined by a dielectric environment in the presence of both Rashba and Dresselhaus spin-orbit interactions. It is demonstrated that off-diagonal components of the conductivity tensor resulting from a delicate interplay between Rashba and Dresselhaus couplings lead to the hybridization of transverse electric and transverse magnetic surface electromagnetic modes localized at the interface. We show that the characteristics of these hybrid surface waves can be controlled by additional intense external off-resonant coherent pumping.

Spatially resolved single photon detection with a quantum sensor array

We propose a method of resolving a spatially coherent signal, which contains on average just a single photon, against the background of local noise at the same frequency. The method is based on detecting the signal simultaneously in several points more than a wavelength apart through the entangling interaction of the incoming photon with the quantum metamaterial sensor array. The interaction produces the spatially correlated quantum state of the sensor array, characterised by a collective observable (e.g., total magnetic moment), which is read out using a quantum nondemolition measurement. We show that the effects of local noise (e.g., fluctuations affecting the elements of the array) are suppressed relative to the signal from the spatially coherent field of the incoming photon as , where N is the number of array elements. The realisation of this approach in the microwave range would be especially useful and is within the reach of current experimental techniques.Abstract We propose a method of detecting the wave front of a single photon in several points more than a photon wavelength apart. It is based on the entangling interaction of the incoming photon with the quantum metamaterial sensor array, which produces the spatially correlated quantum state of the latter, and the quantum nondemolition readout of a collective observable (e.g., total magnetic moment), which characterizes this quantum state. We show that the effects of local noise (e.g., fluctuations affecting the elements of the array) are suppressed relative to the signal from the spatially coherent field of the incoming photon. The realization of this approach in the microwave range would be especially useful and is within the reach of current experimental techniques.

Mimicking graphene with polaritonic spin vortices

Exploring the properties of strongly correlated systems through quantum simulation with photons, cold atoms or polaritons represents an active area of research. In fact, the latter permits to shed the light on the behavior of complex systems which are hardly to be addressed in the laboratory or tackled numerically. In this study we discuss an analogue of graphene formed by exciton-polariton spin vortices arranged into a hexagonal lattice. We show how the graphene-type dispersion at different energy scales arises for several types of exciton-polariton spin vortices. In contrast to previous studies of exciton-polaritons in artificial lattices, the use of exciton-polariton spin vortex modes offers a more rich playground for quantum simulations. In particular, we demonstrate that the sign of the nearest neighbor coupling strength can be inverted.

Flux-flow oscillator (FFO) made with the fluxon cloning circuits

In present paper we have developed a new device, Flux-Flow Oscillator (FFO) where flux cloning phenomena have been demonstrated. Such FFO made with the use of flux cloning circuit can in principle operate even without magnetic field, that is in a very different manner than conventional FFO [1] developed nowadays for practical applications [2, 3]. We have designed such a novel device and build it up with the use of the long Josephson T-shaped junction of a linear overlap geometry made up with Nb-AlO x -Nb technology. We have theoretically described the properties of such a device and the dynamics of vortices there. These theoretical studies have been performed in the framework of a sine-Gordon model, which includes surface losses. Finally we have tested the device experimentally and demonstrated that the flux cloning can lead to a strong coherent terahertz radiation. There the shape of the spectral lines and the current-voltage characteristics have been also measured.