Quadrupole Effects Research Articles

Strange-metal behavior without fine tuning in PrV2Al20

Strange-metal behavior observed in the praseodymium-based heavy-fermion material PrV2Al20 has been tentatively interpreted in the framework of proximity to a quantum critical point (QCP) associated with quadrupolar ordering. Here, we demonstrate that an alternative, natural explanation exists without invoking a QCP, in terms of the unconventional nature of the quadrupolar Kondo effect taking place in non-Kramers ions. Using a combination of density-functional theory calculations and analytical arguments, we construct a periodic Anderson model with realistic parameters to describe PrV2Al20. We solve the model using dynamical mean-field theory preserving the model symmetries and demonstrate the non-Fermi liquid strange-metal behavior stemming from the two-channel nature of the quadrupolar Kondo effect. Our calculations provide an explanation for the puzzling temperature dependence in the magnetic susceptibility and provide a basis for analyzing future photoemission experiments. Published by the American Physical Society 2024

Effect of Quadrupole and Hexadecapole Deformations of Target on Projectile

Effect of Quadrupole and Hexadecapole Deformations of Target on Projectile

Accurate Detection of G-Series Agent Simulants by Pseudo-Multiple Reaction Monitoring on Miniature LIT-MS.

Rapid and accurate on-site detection of chemical warfare agents (CWAs) could defend military and civilian populations against current and emerging chemical weapons. With the development of ambient ionization and linear ion trap technology, the rapid and accurate quantitative determination method of CWAs based on direct ionization and multistage mass spectrometry has attracted widespread attention. In this study, a microliter electrospray ionization-miniature linear ion trap mass spectrometry (LIT-MS) instrument was designed and constructed, and the effects of quadrupole enhanced dipole resonance excitation on the resolution and sensitivity were investigated; consequently, the parameters of CWAs detection were optimized. Based on the broad time-frequency ion excitation technology, accurate multiple reaction monitoring (MRM) quantitative analysis of DMMP (G-series agent simulants, m/z 125 → m/z 93) was obtained. The linear correlation coefficient in the concentration range of 1 to 20 μg/mL could reach 99.02%, and the relative standard deviations (RSD) of continuous repeatability, interday repeatability, and intraday repeatability were all less than 10%. The results showed that the accurate pseudo-MRM detection method based on miniature linear ion trap mass spectrometry for CWAs detection was feasible.

The third post-Newtonian equatorial motion in Kerr spacetime

We calculate the third post-Newtonian (PN) order solution for the equatorial motion of a test particle in Kerr spacetime. In particular, we obtain the effects of the spin-induced quadrupole on the periastron advance and the orbital period at the 3PN order.

Rational design of the PEBA2533 mixed matrix membrane containing metallo-supramolecular polymers for efficient CO2/H2 separation

Mixed-matrix membranes (MMMs) are an effective method for overcoming the trade-off limitations of conventional polymeric membranes and are attractive for CO2/H2 separation. However, major challenges remain in achieving high gas separation performance and long-term stability owing to undesirable polymer/filler interfaces. In this study, a novel metallo-supramolecular polymer (F127-Tpy-M) was designed and selected to engineer a polymer/filler interface. Benefiting from strong intermolecular interactions, F127-Tpy-M dispersed well in the PEBA2533 matrix with a defect-free interface. By synergistically combining the dipole–quadrupole effect of the ethylene oxide groups in F127 and gas–metal interactions, MMMs could significantly improve the gas separation performance. In comparison with the pristine membrane, the MMM with 60% F127-Tpy-M loading exhibited 175–194% and 215–259% increases in CO2/H2 selectivity and CO2 permeability, respectively, which far surpass the 2008 Robeson upper bound. The molecular dynamics simulations supported the experimental data, confirming that F127-Tpy-M is a promising candidate for designing next-generation high-performance MMMs.

Quadrupole assisted optical rectification and corresponding refractive index change in GaAs quantum dot in THz range

We investigate the optical rectification (OR) process and the corresponding refractive index change (RIC) in single electron charged GaAs spherical quantum dot. The effective mass approximation is used with the finite potential including the effect of conduction band nonparabolicity. The OR and the RIC processes are studied including dipole plus quadrupole effects within the framework of the density matrix approach for different dot radii and outside arsenide, nitride and oxide matrix in the terahertz range.

Quadrupole Effects in the Photoionisation of Sodium 3s in the Vicinity of the Dipole Cooper Minimum

A procedure to obtain relativistic expressions for photoionisation angular distribution parameters using the helicity formulation is discussed for open-shell atoms. Electric dipole and quadrupole transition matrix elements were considered in the present work, to study the photoionisation dynamics of the 3s electron of the sodium atom in the vicinity of the dipole Cooper minimum. We studied dipole–quadrupole interference effects on the photoelectron angular distribution in the region of the dipole Cooper minimum. Interference with quadrupole transitions was found to alter the photoelectron angular distribution, even at rather low photon energies. The initial ground and final ionised state discrete wavefunctions of the atom were obtained in the present work using GRASP, and we employed RATIP with discrete wavefunctions, to construct continuum wavefunctions and to calculate transition amplitudes, total cross-sections and angular distribution asymmetry parameters.

Constitutive matrices for 32 typical classes of crystalline solids with couple stress, quadrupole, and curvature-based flexoelectric effects

Constitutive matrices for 32 typical classes of crystalline solids with couple stress, quadrupole, and curvature-based flexoelectric effects

Relativistic coupled-cluster analysis of the second-order effects on the hyperfine structure in Cs133

Using the single and double approximated relativistic coupled-cluster method, we calculate the first-order hyperfine structure constants for the $6{p}_{3/2}, 8{p}_{3/2}, 6{d}_{3/2}, 7{d}_{3/2}$, and $7{d}_{5/2}$ states in $^{133}\mathrm{Cs}$, and also evaluate the second-order magnetic dipole--magnetic dipole, magnetic dipole--electric quadrupole effects caused by the off-diagonal hyperfine interaction. With these calculations, we reanalyze some recent high-precision experimental measurements of the hyperfine splitting intervals of $^{133}\mathrm{Cs}$. We find that the second-order magnetic dipole--magnetic dipole effects are especially sizable at the order of kHz in the $B$ constant for the ${d}_{3/2,5/2}$ states. Our calculations can provide a reference for future higher precision experimental measurements.

Long-range electrostatic contribution to electron-phonon couplings and mobilities of two-dimensional and bulk materials

Charge transport plays a crucial role in manifold potential applications of two-dimensional materials, including field-effect transistors, solar cells, and transparent conductors. At most operating temperatures, charge transport is hindered by scattering of carriers by lattice vibrations. Assessing the intrinsic phonon-limited carrier mobility is thus of paramount importance to identify promising candidates for next-generation devices. Here we provide a framework to efficiently compute the drift and Hall carrier mobility of two-dimensional materials through the Boltzmann transport equation by relying on a Fourier-Wannier interpolation. Building on a recent formulation of long-range contributions to dynamical matrices and phonon dispersions [Phys. Rev. X 11, 041027 (2021)], we extend the approach to electron-phonon coupling including the effect of dynamical dipoles and quadrupoles. We identify an unprecedented contribution associated with the Berry connection that is crucial to preserve the Wannier-gauge covariance of the theory. This contribution is not specific to two-dimensional crystals, but also concerns the three-dimensional case, as we demonstrate via an application to bulk SrO. We showcase our method on a wide selection of relevant monolayers ranging from ${\mathrm{SnS}}_{2}$ to ${\mathrm{MoS}}_{2}$, graphene, BN, InSe, and phosphorene. We also discover a nontrivial temperature evolution of the Hall hole mobility in InSe whereby the mobility increases with temperature above 150 K due to the Mexican-hat electronic structure of the InSe valence bands. Overall, we find that dynamical quadrupoles are essential and can impact the carrier mobility in excess of 75%.

Influence of Residual Quadrupolar Interaction on Quantitative Sodium Brain Magnetic Resonance Imaging of Patients With Multiple Sclerosis.

The purpose of this work was to evaluate the influence of residual quadrupolar interaction on the determination of human brain apparent tissue sodium concentrations (aTSCs) using quantitative sodium magnetic resonance imaging ( 23 Na MRI) in healthy controls (HCs) and patients with multiple sclerosis (MS). Especially, it was investigated if the more detailed examination of residual quadrupolar interaction effects enables further analysis of the observed 23 Na MRI signal increase in MS patients. 23 Na MRI with a 7 T MR system was performed on 21 HC and 50 MS patients covering all MS subtypes (25 patients with relapsing-remitting MS, 14 patients with secondary progressive MS, and 11 patients with primary progressive MS) using 2 different 23 Na pulse sequences for quantification: a commonly used standard sequence (aTSC Std ) as well as a sequence with shorter excitation pulse length and lower flip angle for minimizing signal loss resulting from residual quadrupolar interactions (aTSC SP ). Apparent tissue sodium concentration was determined using the same postprocessing pipeline including correction of the receive profile of the radiofrequency coil, partial volume correction, and relaxation correction. Spin dynamic simulations of spin-3/2 nuclei were performed to aid in the understanding of the measurement results and to get deeper insight in the underlying mechanisms. In normal-appearing white matter (NAWM) of HC and all MS subtypes, the aTSC SP values were approximately 20% higher than the aTSC Std values ( P < 0.001). In addition, the ratio aTSC SP /aTSC Std was significantly higher in NAWM than in normal-appearing gray matter (NAGM) for all subject cohorts ( P < 0.002). In NAWM, aTSC Std values were significantly higher in primary progressive MS compared with HC ( P = 0.01) as well as relapsing-remitting MS ( P = 0.03). However, in contrast, no significant differences between the subject cohorts were found for aTSC SP . Spin simulations assuming the occurrence of residual quadrupolar interaction in NAWM were in good accordance with the measurement results, in particular, the ratio aTSC SP /aTSC Std in NAWM and NAGM. Our results showed that residual quadrupolar interactions in white matter regions of the human brain have an influence on aTSC quantification and therefore must be considered, especially in pathologies with expected microstructural changes such as loss of myelin in MS. Furthermore, the more detailed examination of residual quadrupolar interactions may lead to a better understanding of the pathologies themselves.

Two-Photon Interface of Nuclear Spins Based on the Optonuclear Quadrupolar Effect

Photons and nuclear spins are two well-known building blocks in quantum information science and technology. Establishing an efficient interface between optical photons and nuclear spins, while highly desirable for hybridizing these two quantum systems, is challenging because the interactions between nuclear spins and the environment are usually weak in magnitude, and there is also a formidable gap between nuclear spin frequencies and optical frequencies. In this work, we propose an opto-nuclear quadrupolar (ONQ) effect, whereby optical photons can be efficiently coupled to nuclear spins, similar to Raman scattering. Compared to previous works, ancilla electron spins are not required for the ONQ effect. This leads to advantages such as applicability in defect-free nonmagnetic crystals and longer nuclear spin coherence time. In addition, the frequency of the optical photons can be arbitrary, so they can be fine-tuned to minimize the material heating and to match telecom wavelengths for long-distance communications. Using perturbation theory and first-principles calculations, we demonstrate that the ONQ effect is stronger by several orders of magnitude than other nonlinear optical effects that could couple to nuclear spins. Based on this rationale, we propose promising applications of the ONQ effect, including quantum memory, quantum transduction, and materials isotope spectroscopy. We also discuss issues relevant to the experimental demonstration of the ONQ effect.

Laser Cooling of Nuclear Magnons.

The initialization of nuclear spin to its ground state is challenging due to its small energy scale compared with thermal energy, even at cryogenic temperature. In this Letter, we propose an optonuclear quadrupolar effect, whereby two-color optical photons can efficiently interact with nuclear spins. Leveraging such an optical interface, we demonstrate that nuclear magnons, the collective excitations of nuclear spin ensemble, can be cooled down optically. Under feasible experimental conditions, laser cooling can suppress the population and entropy of nuclear magnons by more than 2 orders of magnitude, which could facilitate the application of nuclear spins in quantum information science.

Quadrupolar photovoltaic effect in the terahertz range in a two-dimensional spin- 32 hole system

We identify a strong photovoltaic response due to the non-linear optical transition between heavy and light hole sub-bands enabled by T_d-symmetry in a quantum well, which we term the quadrupolar photovoltaic effect (QPE). The photovoltaic current exhibits a strong resonance in the vicinity of the heavy hole-light hole splitting, with a magnitude governed by the momentum relaxation time, which can reach nanoseconds in GaAs holes. Since the heavy hole-light hole splitting can be tuned from a few meV to nearly 100 meV the QPE could serve as the basis for a terahertz photo-detector. We discuss strategies for experimental observation and device applications.

Probes of axial and nonaxial hexadecapole deformation effects in nuclei around 230U

The structure properties for even–even nuclei around 230U, located on the hexadecapole-deformation island, are investigated using the potential-energy-surface calculation within the framework of the macroscopic−microscopic model. The impact of different deformation degrees of freedom (including axial and nonaxial quadrupole and hexadecapole deformations) on total energy, shell, and pairing contributions is analyzed, based on the projected energy maps and curves. The single-particle structure is presented and briefly discussed. To a large extent, a much better agreement with experimental data and other theoretical results is obtained if the hexadecapole deformations, especially the axial one, are taken into account. These results could provide useful insights into understanding the effects of different quadrupole and hexadecapole deformations.

Quantifying quadrupole effects in the NMR spectra of spin-1/2 nuclei in rotating solids.

Quantifying the NMR spectra of spin I = 1/2 nuclei coupled to quadrupolar spins (nuclei with spin quantum number, S > 1/2) has remained an arduous task in solid-state magic angle spinning (MAS) NMR experiments. In particular, extraction of chemical shift anisotropy (CSA) tensors from line-shapes of spin I = 1/2 nuclei coupled to quadrupolar spin (S = 1) in MAS experiments has remained challenging owing to the simultaneous presence of both heteronuclear dipolar interactions and quadrupolar interactions. Unlike experiments that involve only spin-1/2 nuclei, both faster spinning frequencies and stronger decoupling field strengths on the quadrupolar spins are essential to average/minimize the contributions from heteronuclear dipolar interactions. To this end, a quantitative theory based on the concept of "effective fields" is proposed to deduce optimal conditions in experiments that involve simultaneous recoupling and decoupling of heteronuclear dipolar interactions. Through analytic expressions, the spectral frequencies and intensities observed in experiments are quantified and rigorously verified. Since extraction of molecular constraints in NMR experiments involves iterative fitting of experimental data, we believe that the analytic expressions derived would speed up and be beneficial in quantifying such experiments.

Subcycle-resolved strong-field tunneling ionization: Identification of magnetic dipole and electric quadrupole effects

Interaction of a strong laser pulse with matter transfers not only energy but also linear momentum of the photons. Recent experimental advances have made it possible to detect the small amount of linear momentum delivered to the photoelectrons in strong-field ionization of atoms. Linear momentum transfer is a unique signature of the laser-atom interaction beyond its dipolar limit. Here, we present a decomposition of the subcycle time-resolved linear momentum transfer in term of its multipolar components. We show that the magnetic dipole contribution dominates the linear momentum transfer during the dynamical tunneling process while the post-ionization longitudinal momentum transfer in the field-driven motion of the electron in the continuum is primarily governed by the electric quadrupole interaction. Alternatively, exploiting the radiation gauge, we identify nondipole momentum transfer effects that scale either linearly or quadratically with the coupling to the laser field. The present results provide detailed insights into the physical mechanisms underlying the subcycle linear momentum transfer induced by nondipole effects.

Effects of electric quadrupole interactions with tunable atomic mirrors

Recent studies have involved electric quadrupole effects in atoms interacting with the evanescent mode. This type of surface mode is usually produced by the total internal reflection in a dielectric-vacuum atz=0, and its intensity distribution is very close to the outer surface z>0 half-space. Coating the planar surface of a dielectric substrate with multilayer dielectric thin film of different thicknesses provides an enhanced in such evanescent modes. This type of mode can be used purely as an atomic mirror. We show that the use of such elements for atomic optics gives significant enhancement of the evanescent mode magnitude without degrading the quality of the atomic reflection process. In addition, the decay depth of the evanescent mode can be conveniently controlled by design parameters. This property keeps the atom-light interaction timeτ, and thus the probability of decay emission, very low, which means a high degree of coherence property.

Time delay in the quadrupole field of a body at rest in the 2PN approximation

The time delay of a light signal in the quadrupole field of a body at rest is determined in the second post-Newtonian (2PN) approximation in harmonic coordinates. For grazing light rays at Sun, Jupiter, and Saturn the 2PN quadrupole effect in time delay amounts up to 0.004, 0.14, and 0.04 pico-second, respectively. These values are compared with the time delay in the first post-Newtonian (1PN and 1.5PN) approximation, where it turns out that only the first eight mass-multipoles and the spin-dipole of these massive bodies are required for a given goal accuracy of 0.001 pico-second in time-delay measurements in the solar system. In addition, the spin-hexapole of Jupiter is required on that scale of accuracy.

Study on the fringe field effect of quadrupoles for CSNS MEBT

Study on the fringe field effect of quadrupoles for CSNS MEBT