A5005508125- Atomic and Molecular Physics
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Frequency and Time Standards
- Nuclear physics research studies
- Advanced Chemical Physics Studies
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Cosmology and Gravitation Theories
- Radioactive Decay and Measurement Techniques
- Quantum, superfluid, helium dynamics
- Scientific Measurement and Uncertainty Evaluation
- Quantum chaos and dynamical systems
- Black Holes and Theoretical Physics
- Nuclear Physics and Applications
- Pulsars and Gravitational Waves Research
- Advanced NMR Techniques and Applications
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Noncommutative and Quantum Gravity Theories
- Astronomy and Astrophysical Research
- Muon and positron interactions and applications
- Quantum Mechanics and Applications
- Physics of Superconductivity and Magnetism
UNSW Sydney
2016-2025
Johannes Gutenberg University Mainz
2016-2024
Helmholtz Institute Mainz
2017-2022
Massey University
2010-2022
GSI Helmholtz Centre for Heavy Ion Research
2021-2022
University of California, Berkeley
2013-2020
Petersburg Nuclear Physics Institute
1994-2019
Kurchatov Institute
2019
TRIUMF
2018
St Petersburg University
2018
We describe the results of a search for time variability fine structure constant alpha using absorption systems in spectra distant quasars. Three large optical data sets and two 21 cm mm provide four independent samples, spanning approximately 23% to 87% age universe. Each sample yields smaller past shows 4 sigma deviation: Delta alpha/alpha = -0.72+/-0.18 x 10(-5) over redshift range 0.5<z<3.5. find no systematic effects which can explain our results. The only potentially significant push...
An order of magnitude sensitivity gain is described for using quasar spectra to investigate possible time or space variation in the fine structure constant $\ensuremath{\alpha}$. Applied a sample 30 absorption systems, spanning redshifts $0.5<z<1.6$, we derive limits on variations $\ensuremath{\alpha}$ over wide range epochs. For whole sample,...
We previously reported Keck telescope observations suggesting a smaller value of the fine structure constant $\ensuremath{\alpha}$ at high redshift. New Very Large Telescope (VLT) data, probing different direction in Universe, shows an inverse evolution; increases Although pattern could be due to as yet undetected systematic effects, with systematics presently understood combined data set fits spatial dipole, significant $4.2\ensuremath{\sigma}$ level, right ascension...
A simple analytical formula, a=a\ifmmode\bar\else\textasciimacron\fi{}[1-tan(\ensuremath{\pi}/n-2)tan{\ensuremath{\Phi}-[\ensuremath{\pi}/2(n-2)]}, is obtained for the scattering length in atomic collisions. Here a\ifmmode\bar\else\textasciimacron\fi{}=cos[\ensuremath{\pi}/(n-2)]{ \ensuremath{\surd}2M\ensuremath{\alpha} /[\ensuremath{\Elzxh}(n-2)]${\mathrm{}}}^{2/(\mathit{n}\mathrm{\ensuremath{-}}2)}$[\ensuremath{\Gamma}(n-3)/(n-2)]/[T(n-1)/(n-2)] mean determined by asymptotic behavior of...
The $^1\mathrm{S}_0$-$^3\mathrm{P}_0$ clock transition frequency $ν_\text{Sr}$ in neutral $^{87}$Sr has been measured relative to the Cs standard by three independent laboratories Boulder, Paris, and Tokyo over last years. agreement on $1\times 10^{-15}$ level makes best agreed-upon optical atomic frequency. We combine periodic variations with $^{199}$Hg$^+$ H-maser data test Local Position Invariance obtaining strongest limits date gravitational-coupling coefficients for fine-structure...
The 7.6(5) eV nuclear magnetic-dipole transition in a single $^{229}\mathrm{Th}^{3+}$ ion may provide the foundation for an optical clock of superb accuracy. A virtual composed stretched states within $5{F}_{5/2}$ electronic ground level both and isomeric manifolds is proposed. It shown to offer unprecedented systematic shift suppression, allowing performance with total fractional inaccuracy approaching $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}$.
We report on a search for ultralow-mass axionlike dark matter by analyzing the ratio of spin-precession frequencies stored ultracold neutrons and 199Hg atoms an axion-induced oscillating electric dipole moment neutron axion-wind effect. No signal consistent with is observed axion mass range 10−24≤ma≤10−17 eV. Our null result sets first laboratory constraints coupling to gluons, which improve astrophysical limits up 3 orders magnitude, also improves previous nucleons factor 40.Received 29...
Abstract Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances ability create, cool, control complex molecules down quantum level, along with recent upcoming species production at several facilities around world, create compelling opportunity coordinate combine these efforts bring precision measurement extreme nuclei. In...
A method is developed for calculation of single-particle occupation numbers in finite Fermi systems interacting particles. It more accurate than the canonical distribution and gives Fermi-Dirac limit large number shown that statistical effects interaction are absorbed by an increase effective temperature. Criteria quantum chaos equilibrium considered. All results confirmed numerical experiments two-body random model.
An ab initio method for high accuracy calculations atoms with more than one valence electron is described. The effective Hamiltonian the electrons formed using many-body perturbation theory interaction of core. configuration-interaction then used to find energy levels atom. application this thallium shows that gives an about 0.5% ionization potential and a few tenths percent first intervals. \textcopyright{} 1996 American Physical Society.
Detection of high-redshift absorption in the optical spectra quasars have provided a powerful tool to measure spatial and temporal variations physical ``constants'' Universe. It is demonstrated that high sensitivity variation fine structure constant alpha can be obtained from comparison heavy light atoms (or molecules). We performed calculations for pair FeII MgII which accurate quasar laboratory are available. A possibility $10^5$ times enhanced effects fundamental constants suitable...
Theories unifying gravity and other interactions suggest the possibility of spatial temporal variation physical ``constants'' in Universe. Detection high-redshift absorption systems intersecting sight lines towards distant quasars provides a powerful tool for measuring these variations. We have previously demonstrated that high sensitivity to fine-structure constant $\ensuremath{\alpha}$ can be obtained by comparing spectra heavy light atoms (or molecules). Here we describe new calculations...
Collective $P$- and $T$-odd moments produced by parity time invariance violating forces in reflection asymmetric nuclei are considered. The enhanced collective Schiff, electric dipole, octupole appear due to the mixing of rotational levels opposite parity. These can exceed single-particle more than 2 orders magnitude. enhancement is nature intrinsic small energy separation between members doublets. In turn these nuclear induce $T$- $P$-odd effects atoms molecules. A simple estimate given a...
The aim of the present paper is to analyze a realistic model quantum chaotic system: spectrum and eigenstates rare-earth atom Ce. Using relativistic configuration-interaction method spectra wave functions odd even levels Ce with J=4 are calculated. It shown that structure excited states at excitation energies above 1 eV becomes similar compound in heavy nuclei. superpositions simple basis (with number ``principal'' components N\ensuremath{\sim}100), built 4f, 6s, 5d, 6p single-electron...
Sensitivity to temporal variation of the fundamental constants may be strongly enhanced in transitions between narrow close levels different nature. This enhancement realized a large number molecules due cancellation ground state fine-structure ${\ensuremath{\omega}}_{f}$ and vibrational interval ${\ensuremath{\omega}}_{v}$ [$\ensuremath{\omega}={\ensuremath{\omega}}_{f}\ensuremath{-}n{\ensuremath{\omega}}_{v}\ensuremath{\approx}0$,...
The relative effects of the variation fine structure constant $\ensuremath{\alpha}={e}^{2}/\ensuremath{\hbar}c$ and dimensionless strong interaction parameter ${m}_{q}/{\ensuremath{\Lambda}}_{\mathrm{QCD}}$ are enhanced by 5--6 orders magnitude in a very narrow ultraviolet transition between ground first excited states $^{229}\mathrm{Th}$ nucleus. It may be possible to investigate this with laser spectroscopy. Such an experiment would have potential improving sensitivity temporal fundamental...
We derive an approximate expression for a "radiative potential" which can be used to calculate QED strong Coulomb field radiative corrections energies and electric dipole (E1) transition amplitudes in many-electron atoms with accuracy of few percent. The expectation value the potential gives energies. Radiative E1 expressed terms its energy derivative (the low-energy theorem): relative magnitude contribution is ~alpha^3 Z^2 ln(1/(alpha^2 Z^2)), while sum other contributions (Z_i+1)^2, where...
We apply the sum-over-states approach to calculate partial contributions parity nonconservation (PNC) in cesium [Porsev, Beloy, and Drevianko, Phys. Rev. Lett. 102, 181601 (2009)]. find significant corrections two nondominating terms coming from contribution of core highly excited states ($n>9$, so called tail). When these differences are taken into account result Porsev et al., ${E}_{\mathrm{PNC}}=0.8906(24)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}i(\ensuremath{-}{Q}_{W}/N)$...
Quasar absorption lines provide a precise test of whether the fine-structure constant, α, is same in different places and through cosmological time. We present new analysis large sample quasar absorption-line spectra obtained using Ultraviolet Visual Echelle Spectrograph (UVES) on Very Large Telescope (VLT) Chile. apply many-multiplet method to derive values Δα/α≡ (αz−α0)/α0 from 154 absorbers, combine these with 141 previous observations at Keck Observatory Hawaii. In VLT sample, we find...
We study atomic systems that are in the frequency range of optical clocks and have enhanced sensitivity to potential time-variation fine structure constant, alpha. The high is due coherent contributions from three factors: nuclear charge Z, ionization degree, significant differences configuration composition states involved. Configuration crossing keeps frequencies despite large energies. discuss a few promising examples largest alpha-sensitivities seen systems.
The Standard Model of particle physics assumes that the so-called fundamental constants are universal and unchanging. Absorption lines arising in molecular clouds along quasar sightlines offer a precise test for variations proton-to-electron mass ratio, μ, over cosmological time distance scales. inversion transitions ammonia particularly sensitive to μ as compared rotational transitions. Comparing available spectra observed toward B0218+357 with new, high-quality spectra, we present first...