Approaching microwave photon sensitivity with Al Josephson junctions

Here, we experimentally test the applicability of an aluminium Josephson junction of a few micrometers size as a single photon counter in the microwave frequency range. We have measured the switching from the superconducting to the resistive state through the absorption of 10 GHz photons. The dependence of the switching probability on the signal power suggests that the switching is initiated by the simultaneous absorption of three and more photons, with a dark count time above 0.01 s

Towards a microwave single-photon counter for searching axions

The major task of detecting axions or axion-like particles has two challenges. On the one hand, the ultimate sensitivity is required, down to the energy of a single microwave photon of the yoctojoule range. On the other hand, since the detected events are supposed to be rare, the dark count rate of the detector must be extremely low. We show that this trade-off can be approached due to the peculiar switching dynamics of an underdamped Josephson junction in the phase diffusion regime. The detection of a few photons\u27 energy at 10 GHz with dark count time above 10 s and the efficiency close to unity was demonstrated. Further enhancements require a detailed investigation of the junction switching dynamics

3-PHENACYLURIDINE-DERIVED HYPNOTICS: ANTHOLOGY, STRUCTUREACTIVITY RELATIONSHIPS AND SYNTHESIS OF SEVERAL ACYCLONUCLEOSIDE ANALOGUES

This work was supported by the Russian Foundation for Basic Research, project # 18-33-00421

Microwave photon detection by an Al Josephson junction

An aluminium Josephson junction (JJ), with a critical current suppressed by a factor of three compared with the maximal value calculated from the gap, is experimentally investigated for application as a threshold detector for microwave photons. We present the preliminary results of measurements of the lifetime of the superconducting state and the probability of switching by a 9 GHz external signal. We found an anomalously large lifetime, not described by the Kramers\u27 theory for the escape time over a barrier under the influence of fluctuations. We explain it by the phase diffusion regime, which is evident from the temperature dependence of the switching current histograms. Therefore, phase diffusion allows for a significant improvement of the noise immunity of a device, radically decreasing the dark count rate, but it will also decrease the single-photon sensitivity of the considered threshold detector. Quantization of the switching probability tilt as a function of the signal attenuation for various bias currents through the JJ is observed, which resembles the differentiation between N and N + 1 photon absorption

Electron-spin-resonance in the doped spin-Peierls compound Cu(1-x)Ni(x)GeO3

ESR-study of the Ni-doped spin-Peierls compound CuGeO3 has been performed in the frequency range 9-75 GHz. At low temperatures the g-factor is smaller than the value expected for Cu- and Ni-ions. This anomaly is explained by the formation of magnetic clusters around the Ni-ions within a nonmagnetic spin-Peierls matrix. The transition into the AFM-state detected earlier by neutron scattering for doped samples was studied by means of ESR. For x=0.032 a gap in the magnetic resonance spectrum is found below the Neel temperature and the spectrum is well described by the theory of antiferromagnetic resonance based on the molecular field approximation. For x=0.017 the spectrum below the Neel point remained gapless. The gapless spectrum of the antiferromagnetic state in weekly doped samples is attributed to the small value of the Neel order parameter and to the magnetically disordered spin-Peierls background.Comment: 16 pages, LATEX, 12 figures, submitted to Journal of Physics : Condensed Matte

Magnetic Resonance of the Intrinsic Defects of the Spin-Peierls Magnet CuGeO3

ESR of the pure monocrystals of CuGeO3 is studied in the frequency range 9-75 GHz and in the temperature interval 1.2-25 K. The splitting of the ESR line into several spectral components is observed below 5 K, in the temperature range where the magnetic susceptibility is suppressed by the spin-Peierls dimerization. The analysis of the magnetic resonance signals allows one to separate the signals of the S=1/2- and S=1 defects of the spin-Peierls phase. The value of g-factor of these signals is close to that of the Cu-ion. The additional line of the magnetic resonance is characterized by an anomalous value of the g-factor and by the threshold-like increase of the microwave susceptibility when the microwave power is increasing. The ESR signals are supposingly attributed to two types of the planar magnetic defects, arising at the boundaries of the domains of the spin-Peierls state with the different values of the phase of the dimerization.Comment: LATEX-text, 12 PS-figures, typos corrected, LATEX-style change

Infiornativity lacrimal fluid interleukins in diagnostics and development of angle-closure glaucoma in elderly subjects

An increased percentage of the elderly subjects in pattern of contemporary society, along with other causes and risk factors, is accompanied by rise in the incidence of glaucoma. By 2020, according to international studies it is expected that prevalence of glaucoma patients in the world would increase up to 80 million subjects. Among the elderly, glaucoma is a common pathology, which development is associated with local disturbances in interleukin profile. However, the features of the latter in patients with primary closed-angle glaucoma in the elderly were poorly examined. Studies of local interleukin status were conducted mainly in patients with suspected or initial manifestations of primary open-angle glaucoma. The features of lacrimal fluid interleukin shift in a target group of elderly patients suffering from stage II primary closed-angle glaucoma virtually gained no attention. In addition, a limited range of local interleukins in patients with such pathology in previous studies was examined. In addition, informativity of lacrimal fluid interleukins in elderly glaucoma patients was not assessed too based on objective methods. The aim of the current study was to outline features and informativity of local interleukin profile indicators in 58 elderly patients with primary closed-angle glaucoma stage II, aged 60—74 years (main group) and 27 age-matched elderly subjects lacking such pathology. The level of interleukins in the lacrimal fluid was determined with the enzyme immunoassay “Multiscan” analyzer (Finland) by using sandwich ELISA (R&D Diagnostic Inc., USA). Informativity of measuring various interleukins was calculated according to the generally accepted formula. It was found that local interleukin profile in elderly patients with primary closed-angle glaucoma was mainly featured with increased amount of IL-2, IL-17, IL-8, but decreased IL-10. Hence, such local interleukins displayed peak informativity. The data obtained should be used in the diagnostics and treatment of such pathology, as well as of applied importance to unveil novel mechanisms behind development, diagnostics and corroboration for selective immuno-tropic therapy of primary closed-angle glaucoma

Environmental contamination and external radiation dose rates from radionuclides released from the Fukushima nuclear power plant

To evaluate the environmental contamination and contributory external exposure after the accident at the Fukushima Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples from each area were analysed by gamma spectrometry. Six artificial radionuclides ( 131I, 134Cs, 137Cs, 129mTe, 95Nb and 136Cs) were detected in soil samples around FNPP. Calculated external effective doses from artificial radionuclide contamination in soil samples around FNPP were 1.9-2.9 μSv h -1 (8.7-17.8 mSv y. -1) in Fukushima city on 22 March 2011. After several months, these calculated external effective doses were 0.25-0.88 μSv h -1 (2.2-7.6 mSv y. -1) in Fukushima city on 29 June 2011. The present study revealed that the detected artificial radionuclides around FNPP mainly shifted to long-lived radionuclides such as radioactive caesium ( 134Cs and 137Cs) even though current levels are decreasing gradually due to the decay of short-lived radionuclides such as 131I, 129mTe, 95Nb and 136Cs. Thus, radiation exposure potency still exists even though the national efforts are ongoing for reducing the annual exposure dose closer to 1 mSv, the public dose limit. Long-term environmental monitoring around FNPP contributes to radiation safety, with a reduction in unnecessary exposure to the residents

Distribution and abundance of western gray whales off northeastern Sakhalin Island, Russia, 2001’003

In 2001’003, >60,000 km of aerial surveys and 7,700 km of vessel surveys were conducted during June to November when critically endangered Korean–Okhotsk or western gray whales (Eschrichtius robustus) were present off the northeast coast of Sakhalin Island, Russia. Results of surveys in all years indicated gray whales occurred in predominantly two areas, (1) adjacent to Piltun Bay, and (2) offshore from Chayvo Bay, hereafter referred to as the Piltun and offshore feeding areas. In the Piltun feeding area, the majority of whales were observed in waters shallower than 20 m and were distributed from several hundred meters to ∼ 5 km from the shoreline. In the offshore feeding area during all years, the distribution of gray whales extended from southwest to northeast in waters 30’5 m in depth. During all years, the distribution and abundance of whales changed in both the Piltun and offshore feeding areas, and both north–south and inshore–offshore movements were documented within and between feeding seasons. The discovery of a significant number of whales feeding in the offshore area each year was a substantial finding of this study and raises questions regarding western gray whale abundance and population levels, feeding behavior and ecology, and individual site-fidelity. Fluctuations in the number of whales observed within the Piltun and offshore feeding areas and few sightings outside of these two areas indicate that gray whales move between the Piltun and offshore feeding areas during their summer–fall feeding season. Seasonal shifts in the distribution and abundance of gray whales between and within both the Piltun and offshore feeding areas are thought, in part, to be a response to seasonal changes in the distribution and abundance of prey. However, the mechanism driving the movements of whales along the northeast coast of Sakhalin Island is likely very complex and influenced by a multitude of factors