Physics Open最新文献

Solar UV radiation influence the Earth's climate and upper atmosphere. The UV emission from the Sun modulates with the sunspot cycle with an 11-year periodicity. The variations in UV, EUV, and X-rays emission are significant during the solar cycle evolution compared to the visible part of the spectrum. The h & k lines of the Mg II spectra emitted from the chromosphere represent the solar UV variability. The sunspot's magnetic fields and dynamics are responsible for the UV and EUV emissions from the solar chromosphere and corona. This paper compares the Mg II core-to-wing ratio of the h & k lines observed at 278 nm wavelength (obtained from Solar Backscattered Ultraviolet Spectrograph (SBUV) instrument onboard the NOAA satellite) with the sunspot area parameter obtained from Royal Greenwich Observatory. When the sunspot group area is small, there is a linear relationship between the sunspot group area and the Mg II index. But a non-linear relationship between the two is observed for the large sunspot group area. There is no phase delay between the appearance of sunspot groups on the solar photosphere and the emission from the Mg II doublet. Apart from 11-year periodicity, we observed common 4.7, 3.2, and 2.2-year periodicity in both the data sets, suggesting the Mg II index is related to the sunspot parameters.

We analyzed the structure of the Thunderstorm Ground Enhancement (TGE) using a particle detector network on Aragats. We performed a statistical analysis of the particle arrival time series on a nanosecond time scale using the largest TGE event on record, which occurred on May 23, 2023. Our findings confirm that the TGE is a mixture of multiple runaway electron avalanches that arrive independently and provide stable particle flux. The electron accelerator, operated by the dipole that emerges in the lower part of the thundercloud, sends copious electrons and gamma rays toward the Earth's surface that sustains for minutes. The experimental results are supported by simulations of electron multiplication and acceleration in strong atmospheric electric fields. We compare TGEs and Terrestrial Gamma Flashes (TGFs), which are brief bursts observed by gamma-ray detectors in orbit and are thought to be associated with atmospheric discharges.

Study was carried out to understand the trends of variation of cross-section values of all possible primary reactions induced by 14 MeV neutrons incident on the most abundant isotope of elements from atomic number 6 to 116. The available nuclear reaction channels and cross-section values of all possible primary reactions were obtained using the theoretical values calculated using TALYS nuclear code version 1.96. The trends were explained on the basis of nuclear binding energy curve, the pairing effect and shell effect. Most of the trends show a regular variation except at some points, which give interesting information for the nucleus where trend is irregular. The variation of the available experimental cross-section values obtained from the EXFOR database, if any, was also obtained and compared with the trends obtained from the theoretical values. The discrepancies in the trends of theoretical and experimental cross-section values of various possible reactions were explained on the basis of the possible errors in experiments and the assumptions of the theoretical model of the TALYS nuclear code.

We study the phase sensitivity of a Mach–Zehnder interferometer (MZI) with product detection (PD) scheme by using the superposition of Schrödinger’s cat-like state with the vacuum state (SCVS) and the coherent state as the inputs. We compare the results derived from PD with the parity detection scheme’s results. We found that PD performs better than parity detection and approaches the single parameter quantum Cramér-Rao bound in some cases. Therefore, we expect that SCVS may play as an alternative quantum resource with PD for the improvement in the phase sensitivity of an MZI having potential application in quantum metrology and quantum sensing.

Theoretically it is shown that high quantum sensitivity of the squeezed state of the Schrodinger cat relative to the non-squeezed state can be achieved. For realization of squeezing the Schrodinger cat state, a parametric process in a nonlinear optical crystal is used. To visualize the squeezed state of the Schrodinger cat with and without a displacement, the values of the Wigner functions are calculated.

Bell states form a complete set of four maximally polarization entangled two-qubit quantum state. Being a key ingredient of many quantum applications such as entanglement based quantum key distribution protocols, superdense coding, quantum teleportation, entanglement swapping etc, Bell states have to be prepared and measured. Spontaneous parametric down-conversion (SPDC) is the easiest way of preparing Bell states and a desired Bell state can be prepared from any entangled photon pair through single-qubit logic gates. In this paper, we present the generation of complete set of Bell states, only by applying unitary transformations of half-wave plate (HWP) on the initial Bell state. The initial Bell state is prepared using a combination of a nonlinear crystal and a beam-splitter (BS) and the rest of the Bell states are created by applying single-qubit logic gates on the entangled photon pairs using HWPs. Our results can be useful in many quantum applications, especially in superdense coding where control over basis of maximally entangled state is required.

AHWR - Critical Facility (AHWR - CF) is a “zero power” reactor designed to carry out various reactor physics experiments for validation of AHWR physics design. AHWR-CF is a vertical tank type reactor. This paper describes the experiments carried out for neutron flux measurements on the reactor tank surface of AHWR-CF. A number of bare Au and cadmium covered Ni foils were used to measure thermal and fast neutron flux at the outer surface of the reactor tank. One cadmium covered Au foil was also irradiated at one of the locations on the tank surface, to estimate the epithermal component of neutron flux. Westcott thermal flux on the tank surface (at an elevation of 120 cm from tank bottom) was found to be (5.48 ± 0.57)E+6 n cm⁻² s⁻¹ on one of the sides of the reactor tank. Cadmium ratio for Au for this location was 40.28, indicating a highly thermalized neutron spectrum. No statistically significant activity was found in the irradiated Ni foils, indicating the absence of fast neutron flux above the measurable threshold. Low value of flux on the reactor tank surface implies that any irradiation damage in the AHWR-CF reactor tank material will be insignificant over its period of operation.

This research suggests an optical sensor to detect alcohol in beverages and liquids that is based on Zeonex backdrop material. The core of the sensor is made up of six hexahedron-shaped cores and heptagonal cladding with circular air holes. The development and implementation of a limited element evaluation to assess the sensing capabilities of sensor technology using PCF were executed using the COMSOL Multiphysics software. With negligible confinement losses, a highly sensitive H-PCF structure has been proposed for the THz range. With sensitivities of 89.50 %, 91.80 %, and 90.81 %, respectively, at the monitoring region of 1 THz, it can detect three distinct alcohols, including ethanol, butanol, and propanol. At a monitoring frequency of 1 THz, the confinement losses for the first alcohol are 5.45 × 10⁻⁰⁸ dB/m, the second alcohol is 6.01 × 10⁻⁰⁸ dB/m, and the third alcohol is 5.60 × 10⁻⁰⁸ dB/m. Furthermore, the essential graphical representations of additional optical properties, including the effective mode index, effective area, and total power fraction, are extensively examined. Thus, it is evident that this sensor could be utilized to detect alcohol in a variety of environments, given that terahertz (THz) wave pulses are commonly employed in both chemical processes and the food and beverage industries.

Quantum walk (QW) is the quantum analog of the random walk. QW is an integral part of the development of numerous quantum algorithms. Hence, an in-depth understanding of QW helps us to grasp the quantum algorithms. We revisit the one-dimensional discrete-time QW and discuss basic steps in detail by incorporating the most general coin operator, constant in both space and time, and a localized initial state using numerical modeling. We investigate the impact of each parameter of the general coin operator on the probability distribution of the quantum walker. We show that by tuning the parameters of the general coin, one can regulate the probability distribution of the walker. We provide an algorithm for the one-dimensional quantum walk driven by the general coin operator. The study on general coin operators also includes the popular coins — Hadamard, Grover, and Fourier.