Moscow University Physics Bulletin最新文献

In some sources, there is information [1, 2, 11, 12] that natural gas may contain radon, but there are no detailed studies of radon emanation from network natural gas, and also this problem of radon emanation from natural gas has an important practical significance in connection with the implementation of the program of gasification of settlements in Yakutia [3]. It is known that radon is one of the main causes of cancer development, including more often lung cancer. Studies conducted in different countries have shown that even low concentrations of radon registered in residential premises create health risks and contribute to the development of lung cancer. It is known that prolonged exposure to radon with an average concentration increased by 100 Bq/m({}^{3}) increases the probability of developing lung cancer by 16(%) [4]. On this basis, the study of radon safety in permafrost conditions is an urgent problem.

At present, generalizations of quantum communication protocols from qubits to systems with higher-dimensional state spaces (qudits) commonly employ mutually unbiased bases (MUB), the construction of which is known for any dimension equal to a prime power. However, in low dimensions, there also exist formally more symmetric state systems described by regular complex polytopes, which are a generalization of the concept of regular polytopes to complex spaces. This work considers the application of a model originally proposed by R. Penrose and based on the geometry of the dodecahedron and two entangled particles with spin 3/2. In a more general case, two arbitrary quantum systems with four basis states (ququarts) can be used instead. It was subsequently shown that this system of 40 states is equivalent to the Witting configuration and is related to the four-dimensional complex polytope described by Coxeter. The paper proposes a quantum key distribution protocol based on contextuality, utilizing this configuration.

At present, hydrogels are attracting increasing interest due to their unique characteristics for use in various fields, such as regenerative medicine, 3D cell culturing, and drug delivery. The main challenge in applying hydrogels in tissue engineering is the accurate assessment of their mechanical characteristics. In this work, a non-invasive method of scanning ion-conductance microscopy (SICM) is used to determine the stiffness of living human neuroblastoma SH-SY5Y cells cultured on a soft, self-assembling hydrogel composed of the Fmoc-FF peptide. The Young’s modulus for SH-SY5Y cells decreases with increasing substrate stiffness, with values of 1015 and 750 Pa on a Petri dish and Fmoc-FF hydrogel, respectively. This method enables simultaneous investigation of the stiffness of living cells and soft hydrogels, which is promising in the field of regenerative medicine.

A new method is proposed for constructing analytical models of nonstationary vector fields based on the local version of the linear integral representation method. Variational formulations of inverse coefficient problems are presented for a system of two nonlinear differential equations describing the motion of a charged magnetic fluid. A uniqueness theorem for the solution of the inverse coefficient problem for the equations of magnetohydrodynamics is formulated.

Using algebraic perturbation theory, the applicability of the quantum oscillator model within the theory of open quantum systems is demonstrated. The case of resonant and nonresonant interactions between two spatially separated oscillators is considered, where each oscillator interacts with its own thermostat at different temperatures. The possibility of the decay of an isolated oscillator into the thermostat of the oscillator-mediator under conditions of its nonresonant interaction with the latter is demonstrated. In all the cases presented, algebraic perturbation theory does not lead to any nonphysical features or contradictions, such as violations of the second law of thermodynamics or discrepancies in the description of these cases within the frameworks of the global and local approaches.

The possibility of using fluorofullerene C({}_{60})F({}_{48}) for the controlled growth of carbon nanotubes and domains of highly ordered graphene, stimulated by intermediate fluorination of the platinum catalyst surface, has been demonstrated. To ensure facile detachment of fluorine atoms from the carbon framework on the Pt(111) surface, the C({}_{60})F({}_{48}) molecule was selected. It is shown that fluorofullerene molecules decompose on the Pt(111) surface, losing fluorine atoms already at room temperature. High-temperature pyrolysis promotes fluorination of the Pt(111) surface and binding of amorphous carbon, inducing sequential growth of carbon nanotubes and graphene with increasing temperature.

The specific features of the theory of resonant interactions of electromagnetic coherent fields with an anharmonic oscillator, as compared to the case of a multilevel atom, are highlighted. It is shown that within the framework of the local approach—the algebraic resonance perturbation theory—it is possible to account for the requirements of the global approach of the theory of open quantum systems. Based on the auxiliary model of the ‘‘internal nonlinearity’’ of the anharmonic oscillator, the possible conditions for the resonance of a coherent wave with an anharmonic oscillator involving the absorption of a single photon are analyzed.

This study proposes a method for parallelizing quantum algorithms in the circuit model based on the technique of quantum gate teleportation. The resulting parallel representation of the algorithm has reduced circuit depth and, consequently, a higher probability of correct execution under conditions of increasing quantum state decoherence over time. The reduction in circuit depth is achieved by increasing circuit width, i.e., the number of qubits simultaneously used in the computation.

A novel method of microprobing scattering media for studying their three-dimensional structure using femtosecond light pulses, propagated to the object and returned back via a bundle of single-mode fibers, is considered. The second harmonic, generated by frequency summation of the backscattered and reference signals, is detected in the process. A number of algorithms for reconstructing the spatial distribution of the attenuation coefficient and their combination have been investigated through computer modeling.

The paper presents the fundamental principles of photometric investigation of exoplanet candidates through the analysis of archival wide-field images obtained with the robotic telescopes of the MASTER Global Network of Lomonosov Moscow State University. An algorithm has been developed and applied for studying transit exoplanet candidates that does not interfere with the primary objectives of the MASTER network—the detection of optical counterparts of high-energy astrophysical sources and the study of processes occurring in them on various time scales. A number of candidates in the field of the microquasar V404 Cyg have been examined. For the candidate TOI-3570.01, a light curve during the transit of the presumed exoplanet has been obtained, consistent with the calculated ephemerides.