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The emergence of Majorana fermion bound states has been studied in several environments. In this paper, we discuss the current-voltage characteristics of a Majorana fermion state as a function of the voltage, temperature, and magnetic field and compare the results to experiment. Based on the agreement and identified parameters, we calculate the noise as possible proof of the emergence of Majorana fermions.

This work proposes a sensitive low-temperature sensor based on the refractive index (RI) method. It uses a one-dimensional (1D) photonic crystal (PC) structure. The proposed sensor design consists of a bilayer stack of dielectric and superconductor materials. YaBa₂Cu₃O₇ is the superconductor utilized in this case, and we consider air to be the dielectric material. The RI of air doesn’t change much with the temperature, especially compared to the superconductor material. YaBa₂Cu₃O₇ is a superconductor that is ideal for temperature sensing applications because of its temperature-dependent RI. The sensing temperature range for the proposed sensor is 35–70K. The crucial structural factors have been precisely adjusted to increase sensing performance. Based on our knowledge, this is done to increase the sensor’s efficiency to levels that are higher than anything previously reported in the literature. Results show that the designed structure achieves an impressive RI sensitivity of 821.53nm/RIU and a temperature sensitivity of 3nm/K. This sensor could be very useful for medical applications for the detection of low temperatures.

A novel concept of a compact mm/submm integrated spectrometers for environmental monitoring for hazardous materials of chemical and biological origin as well as for remote monitoring of the Earth atmosphere is discussed. The agents will be exactly identified by their unique spectral signatures. The assembled on a multi-chip module, cryocooler-mounted Superconducting Integrated SPectromer (SISP) exploits the superior performance of superconducting Josephson junction technology and unique on-chip integration of analog components, analog-to-digital converter, and digital components. Analog components include a superconductor-insulator-superconductor (SIS) mixer with integrated quasioptical antenna, mm-wave local oscillator, and SQUID amplifier for the down-converted (IF) signals. Upon amplification, the IF signal is digitized using a bandpass delta-sigma modulator, followed by real time processing with rapid single flux quantum (RSFQ) circuitry. Experimental results showing both operation of spectrometer components and the way to their successful integration are presented.

We consider the gravity dual of strongly coupled system at a Lifshitz-fixed point and finite temperature, which was constructed in a recent work arXiv:0909.0263. We construct an Abelian–Higgs model in that background and calculate condensation and conductivity using holographic techniques. We find that condensation happens and DC conductivity blows up when temperature turns below a critical value. We also study the zero temperature limit of strongly coupled system at the Lifshitz-fixed point.

We study general models for holographic superconductors with higher correction terms of the scalar field in the four-dimensional AdS black hole background including the matter fields' backreaction on the metric. We explore the effects of the model parameters on the scalar condensation and find that different values of model parameters can determine the order of phase transitions. Moreover, we find that the higher correction terms provide richer physics in the phase transition diagram.

We performed simulations on in-plane current driven Josephson vortex systems in high-T_c cuprates at weak parallel magnetic fields and /or low anisotropies. It is found that the in-plane resistivity is Lorentz-force dependent at small current regime below the melting transition. As the current increases, the Josephson vortex lattice melts dynamically, the Lorentz-force independence of resistivity reappears. These results are possibly related to the experiments on YBCO.

Hydrostatic pressure effect on superconducting transition temperature and the structural transition temperatures were measured upto 1.0 GPa in the La_1.25Nd_0.6Sr_0.15CuO₄ single crystals. We found that the low temperature tetragonal phase was suppressed with drastic increase of T_c at a low pressure of ~0.1 GPa. By comparing the pressure effect on La_1.48Nd_0.4Sr_0.12CuO₄ single crystals, we confirm that pressure is an effective two-way control parameter for controlling stripes and superconductivity in La-Nd-Sr-Cu-O single crystals.

A theoretical investigation of TE nonlinear surface waves propagating in a photosensitive semiconductor-superconductor layers structure is fully described. The dispersion relation has been found and the effect of nonlinearity, operating angular frequency and the effect of temperature of the superconductor on the propagation characteristics have been examined. The power flow has also been studied. It has been shown that temperature and frequency increase the losses.

The effect of nano size Ag addition on the YBa₂Cu₃O_7-δ (Y-123) system has been investigated. 2–15% weight of nano size Ag was added to the Y-123 system prepared by using the sol-gel-solid-state method. The phase purity was investigated by the powder X-ray diffraction method. Energy Dispersive X-ray Analysis (EDAX) was used to determine the distribution of nano Ag in the samples, and the microstructure was observed using a Scanning Electron Microscope (SEM). The transport critical current density was found to increase with increase in nano Ag content.

Using the equivalent single-particle multi-channel network and the Landauer formula, we theoretically study anti-resonances in conductance of a normal metal–superconductor junction with a side-coupled quantum dot. The transport properties depend on the interplay between the Coulomb blockade effect and the Andreev reflection. It is found that the calculated dependence of the conductance on the gate voltage of dot exhibits two anti-resonant conductance dips. This behavior is caused by the destructive interference of the wave directly transmitted through the normal metal–superconductor junction and the wave reflected from the dot. Moreover, we find that the shape of two anti-resonance profile is symmetric, due to the Andreev reflection, depending on the strength of coupling between the quantum dot and normal metal.

Numerical electromagnetic field simulations of high-temperature superconductors (HTSC) bulk were carried out to calculate the magnetic force between the HTSC bulk and the permanent magnet railway (PMR). A 3D-modeling numerical calculation method is proposed using the finite element method. The model is formulated with the magnetic field vector (H-method). The resulting code was written with FORTRAN language. The electric field intensity E and the current density J constitutive relation of HTSC were described with E–J power law. The Kim macro-model is used to describe critical current density J_c of HTSC bulk. Two virtual HTSC bulks were used to solve the critical current density J_c anisotropic properties of HTSC materials. A superconducting levitation system composed of one HTSC bulk and PMR is successfully investigated using the proposed method. By this method, the influence of critical current density on magnetic levitation force of the superconducting levitation system is mathematically studied.

A superconductor connected to normal leads allows to generate Einstein–Podolsky–Rosen pairs by Cooper pair splitting (CPS). It has been realized with quantum dots either defined in carbon nanotubes or InAs nanowires. After establishing the presence of CPS in such devices new works have investigated the effects of a finite potential difference between the quantum dots to improve and characterize the efficiency of CPS. In this paper, we present a generic model for CPS and develop two minimal models specifically for the two experimental realizations and compare them to the experimental data. In addition, we also explore the relation of nonlocal charge transfer to positive current cross-correlation of currents and discuss the temperature dependence of CPS.

The levitation forces of a bulk YBCO superconductor in gradient varying high and low magnetic fields generated from a superconducting magnet were investigated. The magnetic field intensity of the superconducting magnet was measured when the exciting current was 90 A. The magnetic field gradient and magnetic force field were both calculated. The YBCO bulk was cooled by liquid nitrogen in field-cooling (FC) and zero-field-cooling (ZFC) condition. The results showed that the levitation forces increased with increasing the magnetic field intensity. Moreover, the levitation forces were more dependent on magnetic field gradient and magnetic force field than magnetic field intensity.

Superconductor-ferromagnetic (FN) metamaterial with effective magnetic shielding and transmittal properties that allow the cloaking and transferring of static magnetic fields has been introduced. Most metamaterials consist of different arrangements of superconducting and ferromagnetic materials whose performance and feasibility mainly depend on the involved materials, their geometrical distribution and the permeability of each. In this paper, combining the method of transformation optics with the design of metamaterials, we experimentally demonstrated a superconductor-FM metamaterial system, composed of two coaxial cylinders of different lengths, to investigate the influence of the length and the properties of superconducting material on the magnetic transferring properties of the magnetic field produced by the permanent magnets. By comparing the transmittal magnetic field of different cases, the optimal structure has been ultimately achieved in terms of calculating the transmitted magnetic field ratios. The insights attained by the present study are aimed to provide useful implications for the design of wireless energy transmission and increasing the efficiency of magnetic transmittal devices.

In this paper, the superconductor with the competition of superconducting gap and pseudogap in the below crossover temperature region is calculated. The superconducting gap and pseudogap is assumed to arise from independent and competing correlation. The critical temperature, superconducting gap and the specific heat jump are derived in the analytic form and the approximation is used to simplify the equations obtained for the region that crossover temperature and energy of pseudogap are higher than critical temperature. We find that the critical temperature is decreased as the energy of pseudogap and crossover temperature as increased. The superconductor with pseudogap has small specific heat jump in comparison with the BCS value. Increasing the crossover temperature and critical temperature, the specific heat jump is decreased.

To study how Andreev reflection (AR) occurs between a superconductor and a three-dimensional topological insulator (TI), we use superconducting Nb tips to perform point-contact AR spectroscopy at 4.2 K on as-grown single crystals of Bi₂Se₃. Scanning tunneling spectroscopy and scanning tunneling microscopy are also used to characterize the superconducting tip and both the doping level and surface condition of the TI sample. The point-contact measurements show clear spectral signatures of AR, as well as a depression of zero-bias conductance with decreasing junction impedance. The latter observation can be attributed to interfacial Rashba spin-orbit coupling, and the presence of bulk bands at the Fermi level in our samples suggests that bulk states of Bi₂Se₃ are involved in the observed AR.

An ab initio method, based on the plane wave pseudopotential and the generalized gradient approximation (GGA), is performed to investigate the physical properties such as structural, elastic, electronic and bonding properties of newly synthesized Li₂RhSi₃ and predicted Li₂OsSi₃ ternary silicide superconductors for the first time. Both of these compounds are mechanically stable and are brittle in nature. They also have good machinability. Electronic band structures reveal that these compounds have metallic characteristics. They possess complex bonding nature (metallic, covalent and ionic). According to theoretical Vickers hardness, Li₂RhSi₃ is softer than Li₂OsSi₃.

In the present work, we discuss the transmittance properties of one-dimensional (1D) superconductor nanocomposite photonic crystals (PCs) in THz frequency regions. Our modeling is essentially based on the two-fluid model, Maxwell–Garnett model and the characteristic matrix method. The numerical results investigate the appearance of the so-called cutoff frequency. We have obtained the significant effect of some parameters such as the volume fraction, the permittivity of the host material, the size of the nanoparticles and the permittivity of the superconductor material on the properties of the cutoff frequency. The present results may be useful in the optical communications and photonic applications to act as tunable antenna in THz, reflectors and high-pass filter.

The quantum theory for a mesoscopic electric circuit including a Josephson junction with charge discreteness is studied. By considering coupling energy of the mesoscopic capacitor in Josephson junction device, a Hamiltonian describing the dynamics of a quantum mesoscopic electric LC-circuit with charge discreteness is introduced. We first calculate the persistent current on a quantum driven ring including Josephson junction. Then we obtain the persistent current and energy spectrum of a quantum mesoscopic electrical circuit which includes capacitor, inductor, time-dependent external source and Josephson junction.

In this paper, we calculate ab initially the phonon dispersion relationship of the superconductor LaFeAsO and investigate a main property in the superconductor, the oxygen isotope effect. Based on this phonon dispersion relationship, we find the fact that an important reason of the oxygen isotope effect is connected with the phonon. This result agrees well with the experimental data where the power index of the oxygen isotope effect in the superconductor LaFeAsO is small.