Configuration interaction in many-electron atoms may cause anomalies in the fine structure which make the intervals small and very sensitive to variation of the fine structure constant. Repeated precision measurements of these intervals over long period of time can put strong constrain on possible time variation of the fine structure constant. We consider the $5p^4 \ ^3$P$_{2,1,0}$ fine structure multiplet in the ground state of neutral tellurium as an example. Here the effect of change of the fine structure constant is enhanced about one hundred times in the relative change of the small energy interval between the $^3$P$_1$ and $^3$P$_0$ states.
We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time-variation of the fine structure constant, alpha. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest alpha-sensitivities seen in atomic systems.
Theories unifying gravity with other interactions suggest spatial and temporal variation of fundamental ``constants'' in the Universe. A change in the fine structure constant, alpha, could be detected via shifts in the frequencies of atomic transitions in quasar absorption systems. Previous studies of three independent samples of data, containing 143 absorption systems spread from 2 to 10 billion years after big bang, hint that alpha was smaller 7 - 11 billion years ago. To continue this study we urgently need accurate laboratory measurements of atomic transition frequencies. In this paper, we…
A long-standing problem of fine-structure anomalies in muonic atoms is revisited by considering the $Δ2p$ splitting in muonic $^{90}\mathrm{Zr}$, $^{120}\mathrm{Sn}$ and $^{208}\mathrm{Pb}$ and the $Δ3p$ splitting in muonic $^{208}\mathrm{Pb}$. State-of-the-art techniques from both nuclear and atomic physics are brought together in order to perform the most comprehensive to date calculations of nuclear-polarization energy shifts. Barring the more subtle case of muonic $^{208}\mathrm{Pb}$, the results suggest that the dominant calculation uncertainty is much smaller than the persisting discrepa…
Evidence that the fine structure constant, alpha, was different in an early epoch has recently been found in quasar (QSO) absorption spectra. An accurate laboratory measurement of alpha variation could help to distinguish between space and time variation of alpha and possibly confirm the QSO results. We have performed calculations of the relativistic energy shifts that a variation of alpha would cause in a wide range of atomic spectra. A laboratory measurement of how these transition frequencies vary over time is vital in determining whether alpha is varying today.
Calculation of the Dirac hydrogen atom spectrum in the framework of dynamical fine structure constant (alpha) variability discloses a small departure in the laboratory from Sommerfeld's formula for the fine structure shifts, possibly measurable today. And for a distant object in the universe, the wavelength shift of a spectral line specifically ascribable to cosmological alpha variation is found to depend differently on the quantum numbers than in the conventional view. This last result clashes with the conventional wisdom that an atom's spectrum can change with cosmological time only through …
Quasar absorption spectral data indicate the presence of a spatial gradient in the electromagnetic fine-structure constant $α$ on cosmological length scales. We point out that experiments with accelerometers, including torsion pendula and atom interferometers, can be used as sensitive probes of cosmological spatial gradients in the fundamental constants of nature, which give rise to equivalence-principle-violating forces on test masses. Using laboratory data from the Eöt-Wash experiment, we constrain spatial gradients in $α$ along any direction to be $| \boldsymbol{\nabla} α/ α| < 6.6 \times 1…
We perform accurate calculations of the dependence of transition frequencies in two valence electron atoms and ions on a variation of the fine structure constant, alpha. The relativistic Hartree-Fock method is used with many-body perturbation theory and configuration interaction methods to calculate transition frequencies. The results are to be used in atomic-clock-type laboratory experiments designed to test whether alpha varies in time.
We study transitions between ground and low-energy excited states of heavy ions corresponding to s-d single-electron transitions or s^2-d^2 double-electron transitions. The large nuclear charge Z and significant change in angular momentum of electron orbitals make these transitions highly sensitive to a potential variation in the fine-structure constant, alpha. The transitions may be considered as candidates for laboratory searches for space-time variation of alpha.
In this paper we report calculations of the relativistic corrections to transition frequencies (q factors) of Yb II for the transitions from the odd-parity states to the metastable state $4f^{13}6s^2 ^2F_{7/2}^o$. These transitions are of particular interest experimentally since they possess some of the largest q factors calculated to date and the $^2F_{7/2}^o$ state can be prepared with high efficiency. This makes Yb II a very attractive candidate for the laboratory search for variation of the fine-structure constant alpha.
Dependence of transition frequencies on the fine structure constant $α=e^2/\hbar c$ is calculated for several many-electron systems which are used or planned to be used in the laboratory search for the time variation of the fine structure constant. In systems with a large number of electrons in open shells (from 11 to 15) the relative effects of the variation may be strongly enhanced. For the transitions which were considered before the results are in good agreement with previous calculations.
We review recent activity searching for variations in the fundamental constants of nature in quasar absorption spectra and in the laboratory. While research in this direction has been ongoing for many decades, the topic has recently been stimulated by astronomical evidence for spatial variation in the fine-structure constant, alpha. This result could be confirmed using different quasar data and atomic clock measurements, but there are significant challenges to obtain the required accuracy. We review existing measurements and discuss some of the most promising systems where any variations would…
We consider an application of precision frequency measurements to searches for possible time variations of the fundamental physical constants. Current laboratory constraints on variations of the fine structure constant alpha and other fundamental constants are presented.
We consider different options for the search for possible variations of the fundamental constants. We give a brief overview of the results obtained with several methods. We discuss their advantages and disadvantages with respect to simultaneous variations of all constants in both time and space in the range 10^{8}-10^{10} yr. We also suggest a few possibilities for the laboratory search. Particularly, we propose some experiments with the hyperfine structure of hydrogen, deuterium and ytterbium-171 and of some atoms with a small magnetic moment. Other suggestions are for some measurements of th…
It has been proposed that the radio-frequency electric-dipole (E1) transition between two nearly degenerate opposite-parity states in atomic dysprosium should be highly sensitive to possible temporal variation of the fine structure constant ($α$) [V. A. Dzuba, V. V. Flambaum, and J. K. Webb, Phys. Rev. A {\bf 59}, 230 (1999)]. We analyze here an experimental realization of the proposed search in progress in our laboratory, which involves monitoring the E1 transition frequency over a period of time using direct frequency counting techniques. We estimate that a statistical sensitivity of $|\adot…
Recent data on cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of possible variation of other constants. We discuss variation of strong scale and quark masses. We derive the limits on their relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii) Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals.
We propose a new probe of the dependence of the fine structure constant, alpha, on a strong gravitational field using metal lines in the spectra of white dwarf stars. Comparison of laboratory spectra with far-UV astronomical spectra from the white dwarf star G191-B2B recorded by the Hubble Space Telescope Imaging Spectrograph gives limits on the fractional variation of alpha of (Delta alpha/alpha)=(4.2 +- 1.6)x10^(-5) and (-6.1 +- 5.8)x10^(-5) from Fe V and Ni V spectra, respectively, at a dimensionless gravitational potential relative to Earth of (Delta phi) ~ 5x10^(-5). With better determina…
We report precise measurements of ground-state, $λ$-doublet microwave transitions in the hydroxyl radical molecule (OH). Utilizing slow, cold molecules produced by a Stark decelerator we have improved over the precision of the previous best measurement by twenty-five-fold for the F' = 2 $\to$ F = 2 transition, yielding (1 667 358 996 $\pm$ 4) Hz, and by ten-fold for the F' = 1 $\to$ F = 1 transition, yielding (1 665 401 803 $\pm$ 12) Hz. Comparing these laboratory frequencies to those from OH megamasers in interstellar space will allow a sensitivity of 1 ppm for $Δα/α$ over $\sim$$10^{10}$ yea…
There are few good direct laboratory tests of boost invariance for electrons, because the experiments required often involve repeated precision measurements performed at different times of year. However, existing measurements and remeasurements of the 2S-1S two-photon transition frequency in H--which were done to search for a time variation in the fine structure constant--also constitute a measurement of the boost symmetry violation parameter 0.83c_(TX) + 0.51c_(TY) + 0.22c_(TZ) = (4 +/- 8) x 10^(-11). This is an eight order of magnitude improvement over preexisting laboratory bounds, and with…
Detection of high-redshift absorption in the optical spectra of quasars have provided a powerful tool to measure spatial and temporal variations of physical ``constants'' in the Universe. It is demonstrated that high sensitivity to the variation of the fine structure constant alpha can be obtained from a comparison of the spectra of heavy and light atoms (or molecules). We have performed calculations for the pair FeII and MgII for which accurate quasar and laboratory spectra are available. A possibility of $10^5$ times enhanced effects of the fundamental constants variation suitable for labora…
Precision comparisons of different atomic frequency standards over a period of a few years can be used for a sensitive search for temporal variations of fundamental constants. We present recent frequency measurements of the 688 THz transition in the $^{171}$Yb$^+$ ion. For this transition frequency a record over six years is now available, showing that a possible frequency drift relative to a cesium clock can be constrained to $(-0.54\pm0.97)$ Hz/yr, i.e. at the level of $2\cdot10^{-15}$ per year. Combined with precision frequency measurements of an optical frequency in $^{199}$Hg$^+$ and of t…
