We present the results of modeling and simulation of heat propagation processes taking place in SiO2/W/CeB6/W four-layer detection pixel of a thermoelectric single-photon detector after simultaneous absorption of two, three, and four photons with energy 0.8 eV at different distances from each other as well as many photons absorption at different optical delay. Calculations were carried out based on the equation of heat propagation from a limited volume using the three-dimensional matrix method for differential equations. We have shown that a thermoelectric detector is able to count the number of absorbed photons. Detection pixels of usable size and high detection efficiency are found to have a count rate up to 1014 cps.

In this paper, we present the results of simulating heat propagation processes in the thermoelectric detection pixel after absorbing single photons of UV radiation with energies ranging from 7.1 to 124 eV. The detection pixels, with an operating temperature of 1 K, consist of an absorber (W), a thermoelectric sensor (La0.99Ce0.01B6), a heat sink (W), and a substrate (Al2O3). The heat transfer processes in the detection pixels with different layer thicknesses and surface areas were modeled and simulated using the three-dimensional matrix method for differential equations based on the equation of heat propagation from a limited volume. The temporal dependencies of the temperature at various points in the detection pixels and the average temperature of the layers’ surfaces were calculated. The main signal parameters, such as the maximum value, time to the peak value, decay time, full width at half maximum, and signal power, were determined. In addition, the phonon noise, Johnson noise, and the total noise equivalent power of the detection pixels were calculated. The data obtained show how the signal-to-noise ratio (SNR) depends on the energy of the absorbed photon, the geometry of the detection pixel, and the bandwidth of the signal measurement. Moreover, it was observed that the SNR exceeds unity multiple times for the absorption of photons of all considered energies in the detection pixel with a surface area of 1μm2.

The results of computer modeling of the thermoelectric single-photon detector are presented. We observe the processes of heat distribution after absorption of a photon of 0.1-1 keV energy in different parts of the absorber for different geometries of absorbers and thermoelectric sensors. The calculations were carried out by the matrix method for differential equations using parameters for the tungsten absorber and thermoelectric sensor made of (La, Ce)B6. The results of calculations show that it is realistic to detect photons about 0.1-1 keV and determine their energy with accuracy of not less than 1%. High count rates up to 200 GHz can be achieved.

Strontium ruthenates have a lot of similarities with copper oxide superconductors and are a very interesting object for investigation of mechanisms and conditions which lead to high-temperature superconductivity. We report here on multiple experimental indications of superconductivity with the onset above $40\mathrm{K}$ in strontium ruthenate doped by rhenium and selenium with chlorine used as a flux. The main experimental evidence comes from FTIR spectroscopy of this material followed by the ac and dc magnetization, as well as its heat capacity and magnetoresistance. Structural and morphological studies reveal the heterophase nature of this polycrystalline material as well as changes of lattice parameters relative to the original phases. Experimental data provide evidence of higher critical temperature on the surface compared to that in the bulk of the sample.

Using modeling and computer simulation techniques, we conducted a comprehensive analysis of heat propagation processes and noise determination in a nanoscale three-layer detection pixel of a thermoelectric single-photon detector. The detection pixel comprises an absorber, a thermoelectric sensor, and a heat sink stacked on top of each other on a dielectric substrate. Our research was aimed at studying the spread of heat inside the detection pixel following the absorption of single photons with energies ranging from 0.8 to 7.1 eV (1550–175 nm) in tungsten or molybdenum absorbers of various thicknesses. The simulation was executed based on the equation for heat propagation within a limited volume. We explored temporal temperature variations in different regions of the detection pixel and analyzed the average temperature gradient across the sensor and heat sink surfaces. Parameters such as signal power resulting from the photon absorption, equivalent noise power, and signal-to-noise ratio were determined. Our results indicate that detection pixels consisting of W or Mo absorbers, a thermoelectric sensor La0.99Ce0.01B6, and a Mo heat sink, with a 15 nm thick absorber and a surface area of 1 μm2, can effectively detect single photons across a broad spectrum from far ultraviolet to near infrared. The calculated signal-to-noise ratios and temporal characteristics indicate the possibility of using this thermoelectric detection pixel design in optical microchips and large-scale multi-pixel cameras.