Spin Of Nucleus Research Articles

Three-Qutrit Topological SWAP Logic Gate for ISK (<i>I</i> = 1, <i>S</i> = 1, <i>K</i> = 1) Spin System

Three Zeeman levels of spin-1 electron or nucleus are called as qutrits in quantum computation. Then, ISK (I = 1, S = 1, K = 1) spin system can be represented as three-qutrit states. Quantum circuits and algorithms consist of quantum logic gates. By using SWAP logic gate, two quantum states are exchanged. Topological quantum computing can be applied in quantum error correction. In this study, first, Yang-Baxter equation is modified for ISK (I = 1, S = 1, K = 1) spin system. Then three-qutrit topological SWAP logic gate is obtained. This SWAP logic gate is applied for three-qutrit states of ISK (I = 1, S = 1, K = 1) spin system. Three-qutrit SWAP logic gate is also applied to the product operators of ISK (I = 1, S = 1, K = 1) spin system. For these two applications, expected exchange results are found.

A high-resolution natural abundance 33S MAS NMR study of the cementitious mineral ettringite.

Despite the widespread occurrence of sulfur in both natural and man-made materials, the 33S nucleus has only rarely been utilised in solid-state NMR spectroscopy on account of its very low natural abundance (0.76%), low NMR frequency (ν0 = 30.7 MHz at B0 = 9.4 T), and significant nuclear quadrupole moment (spin I = 3/2, Q = -69.4 mb). Satellite-transition magic angle spinning (STMAS) is an NMR method for obtaining high-resolution spectra of half-integer quadrupolar nuclei (spin I > 1/2) in solids and is notable for its intrinsic sensitivity advantage over the similar multiple-quantum (MQMAS) method, especially for nuclei with low NMR frequencies. In this work we demonstrate the feasibility of natural abundance 33S STMAS NMR experiments at B0 = 9.4 T and 20.0 T using a model sulfate sample (Na2SO4 + K2SO4 in a 1 : 1 molar ratio). Furthermore, we undertake a natural abundance 33S STMAS NMR study of the cement-forming mineral ettringite (Ca6Al2(SO4)3(OH)12·26H2O) at B0 = 9.4 T and 20.0 T, resolving a discrepancy in the literature between two previous conventional 33S MAS NMR studies and obtaining an alternative set of 33S NMR parameters that is simultaneously consistent with the MAS and STMAS data at both field strengths.

Controlling the Dynamics of Quadrupolar Spin-1 Nuclei by Means of Average Hamiltonian Theory When Irradiated with Modified Composite Quadrupolar Echo Pulse Sequences.

The importance of the average Hamiltonian theory and its antecedent the Magnus expansion are discussed. The investigation of its convergence in different situations is very important. In this paper, we introduced a well-established approach to minimize the zeroth-order average Hamiltonian for modified composite pulse sequence in quadrupolar spectroscopy of spin-1. We designed two modified composite pulse sequences constructed by modifying the timing sequence in the original composite pulse sequences.17 We tested various configurations of times associated with the free evolution of the spin system in the modified composite pulses. We found that by decreasing the time delays between the pulses associated with the free evolution of spin system, the line shapes become increasingly better until we obtained the new modified composite pulses showing improvement of the signal compared to the original composite pulse sequences.17 This promising work is expected to play an important role not only for recording high resolution spectra of amino acids, pharmaceutical samples, and peptides but also for probing structural and dynamic information in biomolecules. The generality of the present theoretical scheme points to potential applications in solid-state NMR, to problems in chemical physics, quantum mechanics and theoretical developments, chemistry, and physical chemistry, and in interdisciplinary research areas whenever they include spin dynamics approach.

Dynamical simulation of the fission process and anisotropy of the fission fragment angular distributions of excited nuclei produced in fusion reactions

Abstract. A stochastic approach based on four-dimensional Langevin equations was applied to calculate the anisotropy of fission fragment angular distributions, average prescission neutron multiplicity, and the fission probability in a wide range of fissile parameters for the compound nuclei $^{197}\mathrm{Tl},^{225}\mathrm{Pa},^{248}\mathrm{Cf}$, and $^{264}\mathrm{Rf}$ produced in fusion reactions. Three collective shape coordinates plus the projection of total spin of the compound nucleus to the symmetry axis $K$ were considered in the four-dimensional dynamical model. In the dynamical calculations, nuclear dissipation was generated through the chaos-weighted wall and window friction formula. Furthermore, in the dynamical calculations the dissipation coefficient of $K,{\ensuremath{\gamma}}_{k}$ was considered as a free parameter, and its magnitude inferred by fitting measured data on the anisotropy of fission fragment angular distributions for the compound nuclei $^{197}\mathrm{Tl},^{225}\mathrm{Pa},^{248}\mathrm{Cf}$, and $^{264}\mathrm{Rf}$. Comparison of the calculated results for the anisotropy of fission fragment angular distributions with the experimental data showed that the results of the calculations are in good agreement with the experimental data by using values of the dissipation coefficient of $K$ equal to (0.185--0.205), (0.175--0.192), (0.077--0.090), and (0.075--0.085) ${(\mathrm{MeV}\phantom{\rule{0.16em}{0ex}}\mathrm{zs})}^{\ensuremath{-}1/2}$ for the compound nuclei $^{197}\mathrm{Tl},^{225}\mathrm{Pa},^{248}\mathrm{Cf}$, and $^{264}\mathrm{Rf}$, respectively. It was also shown that the influence of the dissipation coefficient of $K$ on the results of the calculations of the prescission neutron multiplicity and fission probability is small.

Construction of two qutrit entanglement by using magnetic resonance selective pulse sequences

Quantum entanglement is essential for some applications of quantum information processing such as quantum cryptography, quantum teleportation and superdence coding. A qubit is a two level quantum system and four two-qubit entangled states called Bell states can be easily obtained for two-qubit states. A qutrit is a three level quantum system and Zeeman levels of spin-1 electron or nucleus can be referred as qutrit. For SI (S=1, I=1) spin system there exist nine two-qutrit states. So nine two-qutrit entangled states can be obtained by using the Hadamard and CNOT logic gates. In this study by considering N+@C60 molecule as SI (S=1, I=1) spin system, two-qutrit entangled states are also obtained by using the magnetic resonance selective pulse sequences of Hadamard and CNOT logic gates. Then it is shown that these entangled states can be transformed into each other by the suggested transformation operators.

Leggett–Garg inequalities violation via the Fermi contact hyperfine interaction

In this paper we examine theoretically how the spin–spin interaction between a nuclei and an electron in the atom affects violation of the Leggett–Garg inequalities. We consider the simplest case of atoms in the state that in the valence shell have just a single electron and the evolution in time of the spin is dictated only by the Fermi contact hyperfine interaction. We found that for special initial conditions and a particular measured observable the high spin nucleus couple to the valence electron such that violation of Leggett–Garg inequalities increases with total spin of states. Consequently, our results show that for the Hydrogen, the smallest atom in Nature, the violation of the Leggett–Garg inequalities is the smallest whereas for the largest atom, the Cesium, the violation is the largest. Moreover, this violation does not depend on a principal quantum number, thus our model can be used for Rydberg atoms in order to test macrorealism for ‘almost macroscopic’ objects.

Classification of T-odd asymmetries for prescission and evaporated light particles in ternary and quaternary nuclear fission induced by cold polarized neutrons

A unified mechanism of the emergence of T-odd ROT- and TRI-asymmetries is proposed for describing experimental T-odd asymmetry coefficients D(θ) in the angular distributions of prescission alphaparticles that are emitted in true ternary and quaternary nuclear fission reactions induced by cold polarized neutrons. The mechanism is related to the different ways in which the Coriolis interaction of the total spin of a polarized compound fissile nucleus with the orbital moment of alpha-particles affects even (for ROT-asymmetries) and odd (for TRI-asymmetries) components of the amplitude of an undisturbed angular distribution of emitted alpha-particles. Coefficients D ROT(θ) and D TRI(θ) derived with this mechanism for T-odd ROT- and TRI-asymmetries successfully describe the dependences of corresponding experimental coefficients for 235U and 239Pu nuclei over the range of angles θ, and for the 233U nucleus in the angular range of 60° < θ < 110°. It is explained why only ROT-type T-odd asymmetries emerge for evaporated neutrons and γ-quanta emitted by fission fragments in similar reactions if we allows for the Coriolis interaction of the total spin of the compound fissile nucleus with the orbital moments of the fission fragments and the wriggling vibrations of the above nucleus near its scission point.

Nuclear spin of odd-oddαemitters based on the behavior ofα-particle preformation probability

The preformation probabilities of an $\ensuremath{\alpha}$ cluster inside radioactive parent nuclei for both odd-even and odd-odd nuclei are investigated. The calculations cover the isotopic chains from Ir to Ac in the mass regions $166\ensuremath{\le}A\ensuremath{\le}215$ and $77\ensuremath{\le}Z\ensuremath{\le}89$. The calculations are employed in the framework of the density-dependent cluster model. A realistic density-dependent nucleon-nucleon $(NN)$ interaction with a finite-range exchange part is used to calculate the microscopic $\ensuremath{\alpha}$-nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the $\ensuremath{\alpha}$ and daughter nuclei has been included in the folding model through the finite-range exchange part of the $NN$ interaction. The calculated potential is then implemented to find both the assault frequency and the penetration probability of the $\ensuremath{\alpha}$ particle by means of the Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. The correlation of the $\ensuremath{\alpha}$-particle preformation probability and the neutron and proton level sequences of the parent nucleus as obtained in our previous work is extended to odd-even and odd-odd nuclei to determine the nuclear spin and parities. Two spin coupling rules are used, namely, strong and weak rules to determine the nuclear spin for odd-odd isotopes. This work can be a useful reference for theoretical calculation of undetermined nuclear spin of odd-odd nuclei in the future.

Spin properties of supermassive black holes with powerful outflows

Abstract Relationships between beam power and accretion disc luminosity are studied for a sample of 55 high excitation radio galaxies (HERG), 13 low excitation radio galaxies (LERG), and 29 radio loud quasars (RLQ) with powerful outflows. The ratio of beam power to disc luminosity tends to be high for LERG, low for RLQ, and spans the full range of values for HERG. Writing general expressions for the disc luminosity and beam power and applying the empirically determined relationships allows a function that parametrizes the spins of the holes to be estimated. Interestingly, one of the solutions that is consistent with the data has a functional form that is remarkably similar to that expected in the generalized Blandford–Znajek model with a magnetic field that is similar in form to that expected in magnetically arrested disk (MAD) and advection-dominated accretion flow (ADAF) models. Values of the spin function, obtained independent of specific outflow models, suggest that spin and active galactic nucleus type are not related for these types of sources. The spin function can be used to solve for black hole spin in the context of particular outflow models, and one example is provided.

Two-dimensional Langevin modeling of fission dynamics of the excited compound nuclei 188Pt, 227Pa and 251Es

A stochastic approach based on one- and two-dimensional Langevin equations is applied to calculate the pre-scission neutron multiplicity, fission probability, anisotropy of fission fragment angular distribution, fission cross section and the evaporation cross section for the compound nuclei 188Pt, 227Pa and 251Es in an intermediate range of excitation energies. The chaos weighted wall and window friction formula are used in the Langevin equations. The elongation parameter, c, is used as the first dimension and projection of the total spin of the compound nucleus onto the symmetry axis, K, considered as the second dimension in Langevin dynamical calculations. A constant dissipation coefficient of K, γK = 0.077(MeV zs)−1/2, is used in two-dimensional calculations to reproduce the above mentioned experimental data. Comparison of the theoretical results of the pre-scission neutron multiplicity, fission probability, fission cross section and the evaporation cross section with the experimental data shows that the results of two-dimensional calculations are in better agreement with the experimental data. Furthermore, it is shown that the two-dimensional Langevin equations together with a dissipation coefficient of K, γK = 0.077(MeV zs)−1/2, can satisfactorily reproduce the anisotropy of fission fragment angular distribution for the heavy compound nucleus 251Es. However, a larger value of γK = 0.250(MeV zs)−1/2 is needed to reproduce the anisotropy of fission fragment angular distribution for the lighter compound nucleus 227Pa.

Composite vector particles in external electromagnetic fields

Lattice quantum chromodynamics (QCD) studies of electromagnetic properties of hadrons and light nuclei, such as magnetic moments and polarizabilities, have proven successful with the use of background field methods. With an implementation of nonuniform background electromagnetic fields, properties such as charge radii and higher electromagnetic multipole moments (for states of higher spin) can be additionally obtained. This can be achieved by matching lattice QCD calculations to a corresponding low-energy effective theory that describes the static and quasi-static response of hadrons and nuclei to weak external fields. With particular interest in the case of vector mesons and spin-1 nuclei such as the deuteron, we present an effective field theory of spin-1 particles coupled to external electromagnetic fields. To constrain the charge radius and the electric quadrupole moment of the composite spin-1 field, the single-particle Green's functions in a linearly varying electric field in space are obtained within the effective theory, providing explicit expressions that can be used to match directly onto lattice QCD correlation functions. The viability of an extraction of the charge radius and the electric quadrupole moment of the deuteron from the upcoming lattice QCD calculations of this nucleus is discussed.

Electromagnetic modulation of monochromatic neutrino beams

We discuss the possibility to produce a modulated monochromatic neutrino beam. Monochromatic neutrinos can be obtained in electron capture by nuclei of atoms or ions. Hydrogen-like ions are of particular interest. It is shown that monochromatic neutrino beam from such hydrogen-like ions with nuclei of non-zero spin can be modulated because of different probabilities of electron capture from hyperfine states. Modulation arises by means of inducing of electromagnetic transitions between the hyperfine states. Requirements for the hydrogen-like ions with necessary properties are discussed. A list of the appropriate nuclei for such ions is presented.

First simultaneous measurement of fission and gamma probabilities of237U and239Np via surrogate reactions

Fission and gamma decay probabilities of 237 U and 239 Np have been mea- sured, for the first time simultaneously in dedicated experiments, via the surrogate re- actions 238 U( 3 He, 4 He) and 238 U( 3 He,d), respectively. While a good agreement between our data and neutron-induced data is found for fission probabilities, gamma decay prob- abilities are several times higher than the corresponding neutron-induced data for each studied nucleus. We study the role of the different spin distributions populated in the surrogate and neutron-induced reactions. The compound nucleus spin distribution popu- lated in the surrogate reaction is extracted from the measured gamma-decay probabilities, and used as input parameter in the statistical model to predict fission probabilities to be compared to our data. A strong disagreement between our data and the prediction is ob- tained. Preliminary results from an additional dedicated experiment confirm the observed discrepancies, indicating the need of a better understanding of the formation and decay processes of the compound nucleus.

Preformation probability inside α emitters having different ground state spin-parity than their daughters

The ground-state spin and parity of a formed daughter in the radioactive Alpha-emitter is expected to influence the preformation probability of the Alpha and daughter clusters inside it. We investigate the Alpha and daughter preformation probability inside odd-A and doubly-odd radioactive nuclei when the daughter and parent are of different spin and/or parity. We consider only the ground-state to ground-state unfavored decays. This is to extract precise information about the effect of the difference in the ground states spin-parity of the involved nuclei far away any influences from the excitation energy if the decays are coming from isomeric states. The calculations are done for 161 Alpha-emitters, with Z=65-112 and N=84-173, in the framework of the extended cluster model, with WKB penetrability and assault frequency. We used a Hamiltonian energy density scheme based on Skyrme-SLy4 interaction to compute the interaction potential. The Alpha plus cluster preformation probability is extracted from the calculated decay width and the experimental half-life time. We discussed in detailed steps the effect of angular momentum of the emitted Alpha-particle on the various physical quantities involved in the unfavored decay process and how it is finally increases the half-life time. We found that if the ground states spin and/or parity of parent and daughter nuclei are different, then the preformation probability of the Alpha-cluster inside parent is less than it would be if they have similar spin-parity. We modified the formula that gives the Alpha preformation probability in terms of the numbers of protons and neutrons outside the shell closures of parent, to account for this hindrance in the preformation probability for the unfavored decays between ground states.

Solid-state NMR indirect detection of nuclei experiencing large anisotropic interactions using spinning sideband-selective pulses

Under Magic-Angle Spinning (MAS), a long radio-frequency (rf) pulse applied on resonance achieves the selective excitation of the center-band of a wide NMR spectrum. We show herein that these rf pulses can be applied on the indirect channel of Hetero-nuclear Multiple-Quantum Correlation (HMQC) sequences, which facilitate the indirect detection via spin-1/2 isotopes of nuclei exhibiting wide spectra. Numerical simulations show that this indirect excitation method is applicable to spin-1/2 nuclei experiencing a large chemical shift anisotropy, as well as to spin-1 isotopes subject to a large quadrupole interaction, such as 14N. The performances of the long pulses are analyzed by the numerical simulations of scalar-mediated HMQC (J-HMQC) experiments indirectly detecting spin-1/2 or spin-1 nuclei, as well as by dipolar-mediated HMQC (D-HMQC) experiments achieving indirect detection of 14N nuclei via 1H in crystalline γ-glycine and N-acetyl-valine samples at a MAS frequency of 60kHz. We show on these solids that for the acquisition of D-HMQC spectra between 1H and 14N nuclei, the efficiency of selective moderate excitation with long-pulses at the 14N Larmor frequency, ν0(14N), is comparable to those with strong excitation pulses at ν0(14N) or 2ν0(14N) frequencies, given the rf field delivered by common solid-state NMR probes. Furthermore, the D-HMQC experiments also demonstrate that the use of long pulses does not produce significant spectral distortions along the 14N dimension. In summary, the use of center-band selective weak pulses is advantageous for HMQC experiments achieving the indirect detection of wide spectra since it (i) requires a moderate rf field, (ii) can be easily optimized, (iii) displays a high robustness to CSAs, offsets, rf-field inhomogeneities, and fluctuations in MAS frequency, and (iv) is little dependent on the quadrupolar coupling constant.

Electromagnetic modulation of monochromatic neutrino beams

A possibility to produce a modulated monochromatic neutrino beam is discussed. Monochromatic neutrinos can be obtained in electron capture by nuclei of atoms or ions, in particular, by nuclei of hydrogen-like ions. It is shown that monochromatic neutrino beam from such hydrogen-like ions with nuclei of non-zero spin can be modulated because of different probabilities of electron capture from hyperfine states. Modulation arises by means of inducing of electromagnetic transitions between the hyperfine states. Requirements for the hydrogen-like ions with necessary properties are discussed. A list of the appropriate nuclei for such ions is presented.

Study of the fission process of 200Pb and 197Tl produced in fusion reactions with the modified statistical model and multidimensional dynamical model

The fission probability, pre-scission neutron, proton and alpha multiplicities, anisotropy of fission fragment angular distribution and the fission time have been calculated for the compound nuclei 200Pb and 197Tl based on the modified statistical model and four-dimensional dynamical model. In dynamical calculations, dissipation was generated through the chaos weighted wall and window friction formula. The projection of the total spin of the compound nucleus to the symmetry axis, K, was considered as the fourth-dimension in Langevin dynamical calculations. In our dynamical calculations, we have used a constant dissipation coefficient of K, and a non-constant dissipation coefficient to reproduce the above-mentioned experimental data. Comparison of the theoretical results of the fission probability and pre-scission particle multiplicities with the experimental data showed that the difference between the results of both dynamical models is small whereas, for the anisotropy of fission fragment angular distribution, it is slightly large. Furthermore, comparison of the results of the modified statistical model with the above-mentioned experimental data showed that with choosing appropriate values of the temperature coefficient of the effective potential, and the scaling factor of the fission-barrier height, the experimental data were satisfactorily reproduced.

Improved parametrization of the unified model forαdecay andαcapture

The updated data for the ground-state-to-ground-state α-transition half-lives in 401 nuclei and the α-capture cross sections of Ca40,Ca44,Co59,Pb,208 and Bi209 are well described in the framework of the unified model for α decay and α capture. The updated values of the α-decay half-lives, the binding energies of nuclei, the spins of parent and daughter nuclei, and the surface deformation parameters are used for the reevaluation of the model parameters. The data for the ground-state-to-ground-state α-decay half-lives are also well described by the empirical relationships.

Study of viscosity on the fission dynamics of the excited nuclei 228U produced in 19F + 209Bi reactions

A two-dimensional (2D) dynamical model based on Langevin equations was applied to study the fission dynamics of the compound nuclei 228 U produced in 19 F + 209 Bi reactions at intermediate excitation energies. The distance between the centers of masses of the future fission fragments was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis, K, was considered as the second dimension in Langevin dynamical calculations. The magnitude of post-saddle friction strength was inferred by fitting measured data on the average pre-scission neutron multiplicity for 228 U . It was shown that the results of calculations are in good agreement with the experimental data by using values of the post-saddle friction equal to 6–8 × 1021 s -1.

Polarizing Nuclear Spins in Silicon Carbide

An optical technique polarizes the spin of nuclei in silicon carbide, offering a potential new route to nuclear spin-based quantum memory.