Physics of Particles and Nuclei最新文献

The article presents the theoretical research results of the basic mechanisms of action of accelerated heavy charged particles on the structures of the central nervous system considering their complex geometry. An analysis is performed of spatial distribution regularities of absorbed dose and the probability of hitting different parts of the cell by particles (body, axon, dendrites, spines) when irradiated with charged particles—from protons to iron ions with energies ranging from 10 to 1000 MeV/nucleon. Reactions leading to the formation of both direct and indirect molecular damage in the genetic apparatus and synapses of neurons are considered, involving physical processes that lead to bond rupture as well as chemical reactions with water radiolysis products. The main modeling parameters needed to verify the calculations using experimental results are also discussed. The data can be used for further analysis of radiation risks during interplanetary missions, as well as for evaluating the side effects of hadron therapy.

In this paper we consider the possibility of the stable migration of the single vibron excitation in the system consisting of biomolecule and the attached molecular structure. The model is based on the assumption of the vibron self-trapping and the formation of the non-adiabatic polaron quasiparticle. We have shown that, contrary to the prediction of the non-polaronic model, excitation occurs at a large intramolecular distance from its origin with high probability for a time long enough to affect the biochemical processes in which the molecular chain participates.

The variational quantum algorithm (VQA) is designed to simulate an (N)-particle wave function of an electronic system of molecules using programmable quantum computers. This brief review, presented at the International Workshop on Mathematical Problems of Quantum Information Technologies (May 2024, Dubna), traces the evolution of the algorithm from a version originating from the unitary coupled cluster method, UCCSD, in computational quantum chemistry to a new version, ADAPT-VQA, adapted for practical implementation on noisy intermediate-scale quantum (NISQ) computing devices.

The repetition of Grover-diffusion operator the order of √N times is the essence of the Grover quantum selection algorithm. For large N the coherence time T2 of the qubits limits the application of the algorithm. We explore what other operators could be devised in its place to accelerate convergence. We present a C++ SU(2) model of the Grover-diffusion operator implemented using our SU2 package.

Motivated by a mathematical model of triangular electrostatic ion trap developed in our previous papers, we present a few analogous results for three uniformly charged coplanar discs. To this end we elaborate upon several earlier results on the Coulomb potential and equilibrium points of three non-collinear point charges. In particular, we establish that the Coulomb potential of the so-called trapping charges is a Morse function and give an explicit formula for its hessian at the trapped point. These facts combined with the recent results of Y.-L. Tsai on three point charges with equal magnitudes, enable us to establish that the Coulomb potential of sufficiently small identical uniformly charged discs centered at the vertices of regular triangle has exactly seven critical points. This implies that, for triangular shapes sufficiently close to the regular triangle, the number of equilibrium points of appropriately charged small discs centered at the vertices is not less than seven.

The possibility of calculating the electronic structure of atomic systems using a noisy quantum computer is investigated. For this purpose, the ground state energy of the moscovium atom is calculated using the Qiskit simulator and the Variational Quantum Eigensolver algorithm with the dUCC-SD ansatz. The algorithm parameters are optimized utilizing the Adam procedure. The robustness of the algorithm to noise is studied in the framework of a two-qubit phase damping noise.

In this research we present a modified version of the simplified quantum hash function that provides improved encoding capabilities and allows to double the amount of classical information stored in the series of single-qubit states. We give the analysis of the one-way property and collision resistance of the proposed function.

We review the relic density of dark matter in the non-standard cosmological scenarios which includes kination models, brane world cosmology and shear dominated universe. Then we use the Planck data to find constraints on the parameter spaces as dark matter cross sections and the five dimentional Planck mass for brane cosmology, enhancement factor for kination model and the inverse-scaled shear temperature for shear dominated universe.

Simulation of the Quantum Approximate Optimization Algorithm (QAOA) was performed using the Cirq software library installed on the HybriLIT quantum computing testbed at JINR. The problem of finding the lowest energy state for the Ising model with a longitudinal magnetic field was solved for two- and three-dimensional lattices of various sizes. Quantum circuits with registers up to 27 qubits were investigated during the study. Optimization of the variational ansatz parameters was carried out using both gradient-based and gradient-free methods. The processes and results of optimization carried out by various methods were compared by a number of parameters.The influence of the configuration of the computing resources used on the efficiency of calculations has been demonstrated.

Transport of ballistic electrons through a 1D-dimensional quantum ring (subjected to Rashba spin–orbit interaction), connected with two external leads, is studied in the presence of external fields. These fields include the optical radiation, produced by an off-resonant high-frequency electric field, and a perpendicular magnetic field. With the aid of the Floquet theory, the key role of the interplay between the optical radiation intensity and the Rashba interaction is established for spin filtering effect of an initially arbitrary polarized electron beam at zero and low magnetic fields.