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Hydrogen chloride (HCl) is a key repository of chlorine in the interstellar medium. Accurate determinations of its abundance are critical to assessing the chlorine elemental abundance and constraining stellar nucleosynthesis models. To aid in modeling recent and future observations of HCl rovibrational spectra, we present cross sections and rate coefficients for collisions between HCl and molecular hydrogen. Transitions between rovibrational states of HCl are considered for temperatures ranging from 10 to 3000 K. Cross sections are computed using a full dimensional quantum close-coupling (CC) method and a reduced dimensionality coupled-states (CS) approach. The CS results, benchmarked against the CC results, are used with a recoupling approach to calculate hyperfine-resolved rate coefficients for rovibrational transitions of HCl induced by H2. The rate coefficients will allow for a better determination of the HCl abundance in the interstellar medium and an improved understanding of interstellar chlorine chemistry. We demonstrate the utility of the new rate coefficients in a nonthermodynamic equilibrium radiative transfer model applied to observations of HCl rovibrational transitions in a circumstellar shell. [ABSTRACT FROM AUTHOR]

The presence of NiGa V N 0 center in cubic gallium nitride (c -GaN), a candidate material for qubit applications, has been proven through first-principles calculation and theoretical analysis. The NiGa V N 0 center is composed of a nitride-vacancy (VN) and an adjacent substitutional nickel atom (NiGa) at the gallium site, possessing the same C 3v structure with the negatively charged nitrogen-vacancy center (NVâ€" center) as the diamond. The NiGa V N 0 center is a spin-triplet, existing in n -type c -GaN. Combined with the group theory, the molecular orbitals (MOs), and the electron distribution of the center were analyzed. Furthermore, regarding the optical properties of the NiGa V N 0 center and maintaining spin-conserving, the electron occupation number in the MOs a 1(2) and exy could be changed, which opens up the prospects for spin manipulation in the NiGa V N 0 center. As a result, the zero-phonon line is found to be relatively low (at about 0.575 eV), which means the optical excitation can be achieved at lower energy. The Stokes and anti-Stokes shifts are shown to be 240 and 153 meV, respectively. Therefore, the findings of this study provide an important basis for quantum computing and networks. In particular, combining the results of the magnetic coupling and hyperfine interaction to achieve the best characteristics of the spintronic center makes it promising for qubit application. [ABSTRACT FROM AUTHOR]

Transition metal defects in SiC give rise to localized electronic states that can be optically addressed in the telecom range in an industrially mature semiconductor platform. This has led to intense scrutiny of the spin and optical properties of these defect centers. For spin-1/2 defects, a combination of the defect symmetry and the strong spin–orbit coupling may restrict the allowed spin transitions, giving rise to defect spins that are long lived, but hard to address via microwave spin manipulation. Here, we show via analytical and numerical results that the presence of a central nuclear spin can lead to a non-trivial mixing of electronic spin states, while preserving the defect symmetry. The interplay between a small applied magnetic field and hyperfine coupling opens up magnetic microwave transitions that are forbidden in the absence of hyperfine coupling, enabling efficient manipulation of the electronic spin. We also find that an electric microwave field parallel to the c-axis can be used to manipulate the electronic spin via modulation of the relative strength of the dipolar hyperfine term. [ABSTRACT FROM AUTHOR]

The relativistic coupled-cluster method has been employed to calculate the energies, magnetic dipole, electric quadrupole and magnetic octupole hyperfine-structure constants of the low-lying states of Ra+. The validity of our calculations is substantiated by comparing the calculated binding energies and magnetic dipole hyperfine-structure constants with the corresponding available experimental results. The combination of our theoretical results with the available experimental values of the electric quadrupole hyperfine-structure constant, makes it possible to extract the electric quadrupole moments Q of the 209,211,221,223Ra nuclei. Our Q(221Ra) = 1.968(34) and Q(223Ra) = 1.248(22) are consistent with the referenced values 1.978(106) and 1.254(66) from a semi-empirical analysis (1988 Z. Phys. D 11 105), but Q(211Ra) = 0.33(2) is smaller than the referenced value 0.48(4) by about 30%. Furthermore, we also performed a procedure for assessing the contributions of magnetic octupole hyperfine interaction to the hyperfine splitting considering the preliminary value of magnetic octupole moment from the single-particle nuclear structure model. The sensitivity of hyperfine-structure interval measurements in 223Ra+ that can reveal the effect caused by the nuclear octupole moment are found to be on the order of kHz. [ABSTRACT FROM AUTHOR]

There is rapidly expanding interest in exploiting the spin of valence-band holes rather than conduction-band electrons for spin qubit semiconductor circuits composed of coupled quantum dots. The hole platform offers stronger spin–orbit interaction (SOI), large difference between in-dot-plane and out-of-dot-plane g-factors, i.e. g-factor anisotropy, and a significantly reduced hyperfine coupling to nuclei in the host material. These attributes collectively can deliver fast all-electric coherent spin manipulation, efficient spin-flip inter-dot tunneling channels, a voltage tunable effective g-factor, a g-factor adjustable to nearly zero in an appropriately oriented external magnetic field, and long spin relaxation and coherence times. Here, we review our recent work on the physics of heavy holes confined in a planar GaAs/AlGaAs double quantum dot system with strong SOI. For a single-hole, we have performed resonant tunneling magneto-spectroscopy to extract spin-flip and spin-conserving tunneling strengths, implemented spin-flip Landau–Zener–Stückelberg–Majorana (LZSM) interferometry, determined the spin relaxation time T1 as a function of magnetic field using a fast single-shot latched charge technique, electrically tuned the effective g-factor revealed by electric dipole spin resonance, and found signatures of the hyperfine interaction and dynamic nuclear polarization with holes. For two-holes, we have measured the energy spectrum in the presence of strong SOI (and so not limited by Pauli spin blockade), quantified the heavy-hole (HH) g-factor anisotropy on tilting the magnetic field, described a scheme to employ HHs whose g-factor is tunable to nearly zero for an in-plane magnetic field for a coherent photon-to-spin interface, and observed a well-defined LZSM interference pattern at small magnetic fields on pulsing through the singlet-triplet anti-crossing. [ABSTRACT FROM AUTHOR]

The law of Biot and Savart, derived by observation of the magnetic field produced by electric current flowing in a macroscopic conductor, is shown to yield the correct expression for the nuclear hyperfine interaction, when applied to the electron circulation current derived for hydrogenic atoms from the theories of Pauli and Dirac, as further developed independently by Darwin, Gordon and Hartree. The law thus applies also on the microscopic scale to the magnetic field generated by the electron probability flux of the various atomic eigenstates, and may clearly be generalised formally for application to many-electron atoms, as outlined by Hartree. The present, fully relativistic, treatment is advantageous in avoiding the usual artificial splitting of the hyperfine interaction into a magnetic dipole–dipole contribution and a separate contribution arising from electron orbital motion. The formula obtained forms the basis for the inclusion of higher order (quantum electrodynamic and nuclear recoil) corrections. Interest in this subject is enhanced by observations of 'strongly forbidden' (magnetic dipole) atomic transitions arising from the nuclear magnetic interaction, notably the 21 cm line of hydrogen, which has played an important role in astrophysics, in both measurements of galactic rotation and studies of the early Universe. [ABSTRACT FROM AUTHOR]

A facile synthesis method is introduced how to prepare magnetically active ultraviolet emitting manganese ions incorporated into ZnSxSe1−x colloidal quantum dot (nanoalloy) at 110 °C in aqueous solutions. The reaction time is the main factor to control the hydrodynamic size from 3 to 10 nm and the precursor ratio is significant to tune the alloy composition. ZnS shell layer on the ZnSxSe1−x core was grown to passivate environmental effects. The nanoalloy has ultraviolet emission at 380 nm having a lifetime of 80 ns and 7% quantum yield. The incorporation of Mn2+ ions into the nanoalloys induced magnetic activity but did not modify the structure and photophysical properties of the nanoalloys. Colloidal and powdery samples were prepared and analyzed by electron paramagnetic resonance (EPR) spectroscopy. In the colloidal dispersions, EPR spectra showed hyperfine line splitting regardless of the Mn2+ ion fractions, up to 6%, indicating that Mn2+ ions incorporated into the nanoalloys were isolated. EPR signals of the powdery samples were broadened when the fraction of Mn2+ ions was higher than 0.1%. The EPR spectra were simulated to reveal the locations and interactions of Mn2+ ions. The simulations suggest that the Mn2+ ions are located on the nanoalloy surfaces. These findings infer that the magnetic dipolar interactions are regulated by the initial mole ratio of Mn/Zn and the physical state of the nanoalloys adjusted by preparation methods. [ABSTRACT FROM AUTHOR]

It is common for senior physics students at many universities to perform optical pumping experiments using a rubidium cell in an integrated apparatus. Such experiments provide an encounter with atomic structure in the context of a standard technique of modern atomic physics. Typically, students investigate radiofrequency resonances between Zeeman levels and measure hyperfine splitting. Despite its pivotal role in aligning the apparatus the so-called zero-field resonance is usually not investigated in such experiments. However it is instructive to look more closely at this phenomenon. We show that it is a consequence of a residual transverse magnetic field that is the result of the inability to align precisely the optical axis of the apparatus in the local N–S direction. The measured width and depth of the resonance-like minimum in transmission is found to be consistent with a very small relaxation rate for the rubidium atoms. In an appendix we show further that the measurements compare well with theory for the Hanle effect in the ground state for an arbitrary magnetic field direction relative to the optical axis of the experiment. [ABSTRACT FROM AUTHOR]

We report observations of the cyanide anion, CN, in the disk around TW Hya covering the N = 1−0, N = 2−1, and N = 3−2 transitions. Using line-stacking techniques, 24 hyperfine transitions are detected out of the 30 within the observed frequency ranges. Exploiting the super-spectral resolution from the line-stacking method reveals the splitting of hyperfine components previously unresolved by laboratory spectroscopy. All transitions display a similar emission morphology, characterized by an azimuthally symmetric ring, peaking at ≈45 au (0.″75), and a diffuse outer tail extending out to the disk edge at ≈200 au. Excitation analyses assuming local thermodynamic equilibrium (LTE) yield excitation temperatures in excess of the derived kinetic temperatures based on the local line widths for all fine-structure groups, suggesting assumptions of LTE are invalid. Using the 0D radiative transfer code RADEX , we demonstrate that such non-LTE effects may be present when the local H2 density drops to 107 cm−3 and below. Comparison with models of TW Hya find similar densities at elevated regions in the disk, typically z / r ≳ 0.2, consistent with model predictions where CN is formed via vibrationally excited H2 in the disk atmospheric layers where UV irradiation is less attenuated. [ABSTRACT FROM AUTHOR]

Angle-frequency coupling in scattering of polarized light on atoms is represented by the angle-dependent (AD) partial frequency redistribution (PRD) matrices. There are several lines in the linearly polarized solar spectrum, for which PRD combined with quantum interference between hyperfine structure states play a significant role. Here we present the solution of the polarized line transfer equation including the AD-PRD matrix for scattering on a two-level atom with hyperfine structure splitting and an unpolarized lower level. We account for the effects of arbitrary magnetic fields (including the incomplete Paschen–Back effect regime) and elastic collisions. For exploratory purposes we consider a self-emitting isothermal planar atmosphere and use atomic parameters that represent an isolated Na i D2 line. For this case we show that the AD-PRD effects are significant for field strengths below about 30 G, but that the computationally much less demanding approximation of angle-averaged PRD may be used for stronger fields. [ABSTRACT FROM AUTHOR]

Short pulses from mode-locked lasers can produce background-free atomic fluorescence by allowing temporal separation of the prompt incidental scatter from the subsequent atomic emission. We use this to improve our quantum state detection of optical-frequency and electron-shelved trapped ion qubits by more than two orders of magnitude. For direct detection of qubits defined on atomic hyperfine structure, however, the large bandwidth of short pulses is greater than the hyperfine splitting, and repeated excitation is not qubit state selective. Here, we show that the state resolution needed for projective quantum measurement of hyperfine qubits can be recovered by applying techniques from coherent control to the orbiting valence electron of the queried ion. We demonstrate electron wavepacket interference to allow readout of the original qubit state using broadband pulses, even in the presence of large amounts of background laser scatter. [ABSTRACT FROM AUTHOR]

Addressing and coherent control of single atoms in solids, with both optical and nuclear spin degrees of freedom is of particularly interest for applications ranging from nanoscale sensing to quantum computing. Here, we performed the spectroscopy study of single praseodymium ions in an yttrium aluminum garnet crystal at cryogenic temperature. The single nuclear spin of individual praseodymium ions is detected through a background-free optical upconversion readout technique. Single ions show stable photoluminescence with spectrally resolved hyperfine splitting of the praseodymium ground state. Based on this measurement, optical Rabi and optically detected nuclear magnetic resonance measurements are performed to study their spin coherence properties. We find short the spin coherence times of praseodymium nuclear spins which we attribute to spin phonon coupling. [ABSTRACT FROM AUTHOR]

In this paper, we present the spectroscopy of the 6P1/2 state in 87Rb using a double-resonance technique at 780 nm and 421 nm. The double-resonance technique is implemented using electromagnetically induced transparency (EIT) and optical pumping methods. Using these spectroscopy methods, we have measured the hyperfine splitting of the 6P1/2 state with precision of <400 kHz, which agrees well with other spectroscopy methods such as electrical discharge and saturated absorption spectroscopy at 421 nm. [ABSTRACT FROM AUTHOR]

Efficient optical pumping is an important tool for state initialization in quantum technologies, such as optical quantum memories. In crystals doped with Kramers rare-earth ions, such as erbium and neodymium, efficient optical pumping is challenging due to the relatively short population lifetimes of the electronic Zeeman levels, of the order of 100 ms at around 4 K. In this article we show that optical pumping of the hyperfine levels in isotopically enriched 145Nd 3+:Y2SiO5 crystals ismore efficient, owing to the longer population relaxation times of hyperfine levels. By optically cycling the population many times through the excited state a nuclear spin flip can be forced in the ground state hyperfine manifold, in which case the population is trapped for several seconds before relaxing back to the pumped hyperfine level. To demonstrate the effectiveness of this approach in applications we perform an atomic frequency comb memory experiment with 33% storage efficiency in 145Nd 3+:Y2SiO5, which is on a par with results obtained in non-Kramers ions, e.g. europium and praseodymium, where optical pumping is generally efficient due to the quenched electronic spin. Efficient optical pumping in neodymium-doped crystals is also of interest for spectral filtering in biomedical imaging, as neodymium has an absorption wavelength compatible with tissue imaging. In addition to these applications, our study is of interest for understanding spin dynamics in Kramers ions with nuclear spin. [ABSTRACT FROM AUTHOR]

High resolution two-photon spectrum of the transitions 6S1/2 → 6P3/2 → 8S1/2, 9S1/2 and 6S1/2 → 6P1/2 → 7D3/2 in neutral 133Cs are presented in a room-temperature vapor cell using a femtosecond optical frequency comb. Spectra are obtained by scanning the repetition frequency of the femtosecond optical frequency comb over the two-photon hyperfine structure. The centroid frequency of the 6S1/2 → 8S1/2, 9S1/2, 7D3/2 transitions are 729009798.80(17) MHz, 806761363.96(11) MHz, and 780894762.595(23) MHz, respectively. The hyperfine coupling constants of the corresponding states are also obtained. The results are consistent with the previous measurements. [ABSTRACT FROM AUTHOR]

The elementary excitation spectrum of a two-component Bose—Einstein condensate in different hyperfine states is obtained by Green's function method. It is found to have two branches. In the long wave-length limit, the two branches of the excitation spectrum are reduced to one phonon excitation and one single-particle excitation. The single-particle one has an energy gap. When the energy gap exists, we study the Landau critical velocity and the depletion of the condensate. With the obtained Green's functions, we calculate the structure factor of a two-component condensate. It is found that the static structure factor comprises only the branch of the phonon excitation and the single-particle excitation makes no contribution to the structure factor. [ABSTRACT FROM AUTHOR]

We present a six-level atomic system using a density matrix approach to show variation of the optical properties in an ...-type Doppler-broadened system for the D2 line of alkali atoms with the nuclear spin I = 3/2, i.e. 87Rb, 23Na and 7Li. The variation in optical properties arises due to the presence of multiple excited states with varying separations. These excited states cause asymmetry in absorption profiles. This asymmetric nature is more prominent for an atom with more closely spaced hyperfine levels in the excited state. In room temperature atomic vapour, the enhanced absorption at the line centre starts to disappear with a decrease in hyperfine separation. We also discuss the transient behaviour of considered atoms, which is in good agreement with an absorption profile in each case. This approach opens a possibility of realizing the optical switching application in a realistic atom. [ABSTRACT FROM AUTHOR]

This report summarizes progress made in understanding properties such as zero-phonon-line energies, emission and absorption polarizations, electron–phonon couplings, strain tuning and hyperfine coupling of single photon emitters in hexagonal boron nitride. The primary aims of this research are to discover the chemical nature of the emitting centres and to facilitate deployment in device applications. Critical analyses of the experimental literature and data interpretation, as well as theoretical approaches used to predict properties, are made. In particular, computational and theoretical limitations and challenges are discussed, with a range of suggestions made to overcome these limitations, striving to achieve realistic predictions concerning the nature of emitting centers. A symbiotic relationship is required in which calculations focus on properties that can easily be measured, whilst experiments deliver results in a form facilitating mass-produced calculations. [ABSTRACT FROM AUTHOR]

A method for calculating the properties of Rydberg states and Rydberg–Rydberg interaction between two 87Sr atoms is described. The method is based on a multichannel quantum defect theory description of the Rydberg states that accounts for the hyperfine splitting of the 87Sr+ ground state. Results are given for the scalar and tensor polarizabilities and the eigenvalues of the C6 matrix for the 5sns FT = 9/2 series. These results illustrate the new features that arise due to the hyperfine splitting of the thresholds. In particular, there should be several couple Förster resonances above n = 50 unlike the case of 88Sr which has none. [ABSTRACT FROM AUTHOR]

When multiple star-forming gas structures overlap along the line of sight and emit optically thin emission at significantly different radial velocities, the emission can become non-Gaussian and often exhibits two distinct peaks. Traditional line-fitting techniques can fail to account adequately for these double-peaked profiles, providing inaccurate measurements of cloud kinematics. We present a new method, called Convnet Line-fitting Of Velocities in Emission-line Regions (CLOVER), for distinguishing between one-component, two-component, and noise-only emission lines using 1D convolutional neural networks trained with synthetic spectral cubes. CLOVER utilizes spatial information in spectral cubes by predicting on 3 × 3 pixel subcubes, using both the central pixel’s spectrum and the average spectrum over the 3 × 3 grid as input. On an unseen set of 10,000 synthetic spectral cubes in each predicted class, CLOVER has classification accuracies of ∼99% for the one-component class and ∼97% for the two-component class. For the noise-only class, which is analogous to a signal-to-noise cutoff of four for traditional line-fitting methods, CLOVER has classification accuracy of 100%. CLOVER also has exceptional performance on real observations, correctly distinguishing between the three classes across a variety of star-forming regions. In addition, CLOVER quickly and accurately extracts kinematics directly from spectra identified as two-component class members. Moreover, we show that CLOVER is easily scalable to emission lines with hyperfine splitting, making it an attractive tool in the new era of large-scale NH3 and N2H+ mapping surveys. [ABSTRACT FROM AUTHOR]

Quantum interference effects, together with partial frequency redistribution (PFR) in line scattering, produce subtle signatures in the so-called Second Solar Spectrum (the linearly polarized spectrum of the Sun). These signatures are modified in the presence of arbitrary strength magnetic fields via the Hanle, Zeeman, and Paschen–Back effects. In the present paper we solve the problem of polarized line formation in a magnetized atmosphere taking into account scattering in a two-level atom with hyperfine structure splitting together with PFR. To this end we incorporate the collisionless PFR matrix derived in Sowmya et al. in the polarized transfer equation. We apply the scattering expansion method to solve this transfer equation. We study the combined effects of PFR and the Paschen–Back effect on polarized line profiles formed in an isothermal one-dimensional planar atmosphere. For this purpose, we consider the cases of D2 lines of Li i and Na i. [ABSTRACT FROM AUTHOR]

In order to accurately evaluate hyperfine interaction (HFI) (both the isotropic, Fermi contact term and the anisotropic, dipole interaction term) of spin-polarized atoms and molecules, we newly implement the cubic harmonics routines for calculating HFI in the all-electron mixed basis code, TOMBO, in which both plane waves (PWs) and atomic orbitals (AOs) are used as basis functions, and AOs are restricted inside the non-overlapping atomic spheres and composed of the numerical radial function on a logarithmic radial mesh and analytic cubic harmonics. The method has a distinct merit of describing the cusp behavior near the nucleus position, which is essential for the Fermi contact term, and of significantly reducing the required cutoff energy for PWs compared to the usual PW expansion approach accompanied with the pseudopotential or PAW method. We also considered the contributions from surrounding atoms in the dipole interaction. Calculated results show excellent agreement with the experimental data, indicating the excellent performance of the code. [ABSTRACT FROM AUTHOR]

Eigenvalue problems for linear differential equations, such as time-independent Schrödinger equations, can be generalized to eigenvalue problems for nonlinear differential equations. In the nonlinear context a separatrix plays the role of an eigenfunction and the initial conditions that give rise to the separatrix play the role of eigenvalues. Previously studied examples of nonlinear differential equations that possess discrete eigenvalue spectra are the first-order equation and the first, second, and fourth Painlevé transcendents. It is shown here that the differential equations for the first and second Painlevé transcendents can be generalized to large classes of nonlinear differential equations, all of which have discrete eigenvalue spectra. The large-eigenvalue behavior is studied in detail, both analytically and numerically, and remarkable new features, such as hyperfine splitting of eigenvalues, are described quantitatively. [ABSTRACT FROM AUTHOR]

The possibility to shield short-range dynamics between colliding particles of an ultracold gas with an optical field is controlled by the details of their long-range interactions. Using an asymptotic model presented in a previous work (Orbán et al 2015 Phys. Rev. A 92 032510), we determine the long-range interaction between an excited and a ground-state alkali-metal atom, including their hyperfine structure. As an example we focus on the bosonic pair 39K() + 133Cs(), which corresponds to the second dissociation limit of the KCs molecule above the ground state. Several excited electronic states are found repulsive at large interatomic distances, being thus promising candidates for optical shielding. The results reveal that the hyperfine coupling scheme is essentially different from the one described in (Orbán et al 2015 Phys. Rev. A 92 032510) for the states correlated to the 39K() + 133Cs(). [ABSTRACT FROM AUTHOR]

A velocity-selective spectroscopy technique for studying the spectra of Rydberg gases is presented. This method provides high-resolution spectrum measurements. We present experimental results for a ladder system 6S1/2 → 6P3/2 →nS(D) electromagnetically-induced transparency involving highly-excited Rydberg states. Based on a radio-frequency modulation technique, we measure the hyperfine structure splitting of intermediate states and the fine structure splitting of Rydberg states in a room temperature 133Cs vapor cell. The experimental data and theoretical predictions show excellent agreement. [ABSTRACT FROM AUTHOR]

We have recently reported on the first direct measurement of the hyperfine transition in lithium-like bismuth (209Bi80+) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. Combined with a new measurement of the hyperfine splitting (HFS) in hydrogen-like (209Bi82+) the so-called specific difference meV could be determined and was found to be in good agreement with its prediction from strong-field bound-state quantum electrodynamics. Here we report on additional investigations performed to estimate systematic uncertainties of these results and on details of the experimental setup. We show that the dominating uncertainty arises from insufficient knowledge of the ion beam velocity which is determined by the electron-cooler voltage. Two routes to obtain a cooler-voltage calibration are discussed and it is shown that agreement can be reached either between the experimental and the theoretical result, or between the two measurements of the HFS in hydrogen-like bismuth, but not both at the same time. [ABSTRACT FROM AUTHOR]

We have performed a Mössbauer investigation of oxygen-vacancy formation on a doped substitutional solution of Sn1−yMyO2 (M  =  Al, Fe, Ce and Er) nanoparticles. Experimental results were assessed from Mössbauer spectroscopy data, which suggest the rise of the oxygen-vacancy population while increasing the content of dopant ions (M). Likewise, we have analyzed the dependence of the structural, electronic and hyperfine properties on the oxygen-vacancy concentration through first-principles calculations of the SnO2−x (where x varies from 0 to 0.25) system. The results obtained from the isomer shift and quadrupole splitting indicate a significant dependence of the hyperfine properties on the number of oxygen vacancies. Moreover, after structural optimization of the Sn16O32-Vo supercell (where Vo is the number of oxygen vacancies) we found an increase of the unit-cell volume with the increase of Vo, while the bulk modulus showed a linear decrease with Vo. Indeed, our results corroborate the experimental findings for pure and transition-metal-doped SnO2 systems for which the presence of the oxygen vacancy plays a key role. [ABSTRACT FROM AUTHOR]

On the basis of the quasipotential approach in quantum electrodynamics, we calculate vacuum polarization and quadrupole corrections in the first and second orders of perturbation theory in the hyperfine structure of P-states in muonic deuterium. All corrections are presented in integral form and are evaluated analytically and numerically. The obtained results can be used for the improvement of the transition frequencies between levels 2P and 2S. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance has emerged as a vital tool to explore the fundamental physics of Kondo lattice systems. Because nuclear spins experience two different hyperfine couplings to the itinerant conduction electrons and to the local f moments, the Knight shift can probe multiple types of spin correlations that are not accessible via other techniques. The Knight shift provides direct information about the onset of heavy electron coherence and the emergence of the heavy electron fluid. [ABSTRACT FROM AUTHOR]

The thermalization parameter of positronium in pure isobutane gas was measured in order to take into account the thermalization effect on precision measurements of the ground-state hyperfine splitting (HFS) of positronium. The momentum-transfer cross section was measured to be for positroniums with kinetic energy below 0.17 eV. Using this value, our new HFS experiment revealed that the positronium thermalization effect on HFS was as large as . In this article, we show the details of Ps thermalization measurement, which have not been published before, and also its effect on HFS. [ABSTRACT FROM AUTHOR]

The direct collapse black hole (DCBH) scenario describes the isothermal collapse of a pristine gas cloud directly into a massive, 104–106 black hole. In this paper we show that large H i column densities of primordial gas at K with low molecular abundance—which represent key aspects of the DCBH scenario—provide optimal conditions for the pumping of the 2p-level of atomic hydrogen by trapped Lyα photons. This Lyα pumping mechanism gives rise to an inverted level population of the transition, and therefore also gives rise to stimulated fine structure emission at (rest-frame). We show that simplified models of the DCBH scenario amplify the CMB by up to a factor of , above which the maser saturates. Hyperfine splitting of the 3 cm transition gives rise to a characteristic broad (FWHM ∼ tens of MHz in the observers frame) asymmetric line profile. This signal subtends an angular scale of ∼1–10 mas, which translates to a flux of ∼0.3–3 μJy, which is detectable with ultra-deep surveys being planned with SKA1-MID. While challenging, as the signal is visible for a fraction of the collapse time of the cloud, the matching required physical conditions imply that a detection of the redshifted 3-cm emission line could provide direct evidence for the DCBH scenario. [ABSTRACT FROM AUTHOR]

A high-resolution two-photon spectrum of 5S1/2 → 5P3/2 → 5D5/2 transitions in a thermal 85Rb vapor cell is presented by using an optical frequency comb and a cw laser. The fluorescence of 6P3/2 → 5S1/2 spontaneous emission is detected when the cw laser frequency is scanned from the 5S1/2 ground state to 5P3/2 hyperfine levels and the optical frequency comb repetition rate is fixed. The hyperfine splittings (Ff = 2–5) of the 5D5/2 excited state are well resolved. The dependences of fluorescence intensities on the cw laser intensity and temperature of 85Rb vapor cell are studied, respectively. The experimental results are in good agreement with the theoretical analyses. [ABSTRACT FROM AUTHOR]

We report the first nuclear magnetic resonance (NMR) study on single crystals of staircase Kagomé antiferromagnet PbCu3TeO7 (TN1 ∼36 K). A Curie constant Θ ∼ −140 K is obtained by a Curie–Weiss fit to the high-temperature Knight shift of 125Te. The hyperfine coupling constant is estimated to be 125Ahf = −67 kOe/μB, and a strong interlayer coupling among staircase Kagomé planes is suggested with such a large hyperfine coupling, according to the lattice structure. The 63,65Cu NMR spectra are found by the zero-field (ZF) NMR at T = 2 K, and the internal hyperfine fields are estimated to be 10.3 T and 9.6 T, for Cu(1) and Cu(2) sites, respectively, in the lattice. A second type of ZF NMR signal with a large rf enhancement is also seen after field-cycling through a high magnetic field. [ABSTRACT FROM AUTHOR]

A semiclassical, four-level model of a nanosecond, chirped pulse interacting with all optically accessible hyperfine states in an ultracold alkali atom, e.g., the 85Rb, is analyzed aiming at population inversion within 5S1/2 electronic state. The nature of two-photon adiabatic passage performed by a single pulse having the bandwidth prior to chirping significantly narrower than the hyperfine splitting of 5S1/2 state is investigated in the framework of the dressed state picture. It is shown that two dressed states are involved in the adiabatic dynamics of population inversion. The excited state manifold appeared to play an important mediating role in the mechanism of population transfer. [ABSTRACT FROM AUTHOR]

On the basis of perturbation theory in the fine structure constant α and the mass ratio of the electron and muon, we calculate the one-loop vacuum polarization, electron vertex corrections, nuclear structure and recoil corrections of the hyperfine splitting of the ground state in muonic lithium ions and . We obtain complete results for small hyperfine splittings of the ground state in of MHz and MHz and in MHz and MHz, which can be regarded as a reliable estimates for comparison with future experimental data. [ABSTRACT FROM AUTHOR]

In view of recent experiments in ultracold atomic systems, the photoassociation of Efimov trimers, composed of three identical bosons, is studied utilizing the multipole expansion. We study both the normal hierarchy case, where one-body current is dominant, and the strong hierarchy case, relevant for photoassociation in ultracold atoms, where two-body current is dominant. For identical particles in the normal hierarchy case, the leading contribution comes from the r2s-mode operator and from the quadrupole d-mode operator. The s-mode reaction is found to be dominant at low temperature, while as the temperature increases the d-mode becomes as significant. For the strong hierarchy case, the leading contribution comes from a 2-body s-wave δ operator. In both cases log periodic oscillations are found in the cross section. For large but finite scattering length the amplitude of the oscillations becomes larger in comparison to infinite scattering length case. We apply our theory to photoassociation of 7Li ultracold atoms and show a good fit to the available experimental results. [ABSTRACT FROM AUTHOR]

The ASACUSA antihydrogen setup at the CERN Antiproton Decelerator (AD) consists of an antihydrogen source (cusp magnet coupled to a positron source and an antiproton catching magnet) followed by a spectrometer beamline. After production in the cusp, the antihydrogen atoms decay while they escape the trap leading to changes in their effective magnetic moment which in turn affect their trajectories in the beamline. Those sequential decays in the presence of a varying magnetic field strength from their production point in the cusp to their detection at the end of the spectrometer line can in principle greatly affect the prospects for a precision measurement of the antihydrogen hyperfine splitting given the so-far relatively low number of available anti-atoms. The impact of the antihydrogen decay in this context has for the first time been simulated. The implementation of atomic radiative decay has been done in Geant4 to extend the particle tracking capabilities originally embedded in Geant4 to excited atoms, and to allow studies of the effect of dynamic atomic properties on trajectories. This new tool thus allows the study of particle–matter interaction via the Geant4 toolkit while properly taking into account the atomic nature of the object under study. The implementation as well as impacts on the experimental sensitivity for antihydrogen spectroscopy are discussed in this paper. [ABSTRACT FROM AUTHOR]

We report an improved measurement of the hyperfine splitting in hydrogen-like bismuth (209Bi82+) at the experimental storage ring ESR at GSI by laser spectroscopy on a coasting beam. Accuracy was improved by about an order of magnitude compared to the first observation in 1994. The most important improvement is an in situ high voltage measurement at the electron cooler (EC) platform with an accuracy at the 10 ppm level. Furthermore, the space charge effect of the EC current on the ion velocity was determined with two independent techniques that provided consistent results. The result of nm provides an important reference value for experiments testing bound-state quantum electrodynamics in the strong magnetic field regime by evaluating the specific difference between the splittings in the hydrogen-like and lithium-like ions. [ABSTRACT FROM AUTHOR]