NIST Primary Frequency Standards and the Realization of the SI Second

Lombardi, Michael A.; Heavner, Thomas P.; Jefferts, Steven R.

doi:10.1080/19315775.2007.11721402

Cited by 46 publications

(39 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Results of our energy calculations are summarized in Table I. Columns 2-7 of Table I give the lowest-order DF energies E (0) , secondorder and third-order Coulomb correlation energies E (2) and E (3) , first-order and second-order Breit corrections B (1) and B (2) , and an estimated Lamb shift contribution, E (LS) . The Lamb shift E (LS) is calculated as the sum of the one-electron self energy and the first-order vacuum-polarization energy.…”

Section: Energy Levelsmentioning

confidence: 99%

“…The present relative standard uncertainty of Cs microwave frequency standard is around 4 × 10 −16 [1]. More precise frequency standards will open ways to more sensitive quantum-based standards for applications such as measurements of the fundamental constants and testing of physics postulates, inertial navigation, magnetometry, gravity gradiometry, and tracking of deepspace probes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca+

Safronova

2011

Phys. Rev. A

View full text Add to dashboard Cite

A systematic study of Ca + atomic properties is carried out using high-precision relativistic allorder method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the levels up to n = 7. Recommended values and estimates of their uncertainties are provided for a large number of electric-dipole transitions. Electric-dipole scalar polarizabilities for the 5s, 6s, 7s, 8s, 4pj , 5pj, 3dj , and 4dj states and tensor polarizabilities for the 4p 3/2 , 5p 3/2 , 3dj , and 4dj states in Ca + are calculated. Methods are developed to accurately treat the contributions from highly-excited states, resulting in significant (factor of 3) improvement in accuracy of the 3d 5/2 static polarizability value, 31.8(3) a + is calculated to be 0.381(4) Hz at room temperature, T = 300 K. Electric-quadrupole 4s−nd and electric-octupole 4s−nf matrix elements are calculated to obtain the ground state multipole E2 and E3 static polarizabilities. Excitation energies of the ns, np, nd, nf , and ng states with n ≤ 7 in are evaluated and compared with experiment. Recommended values are provided for the 7p 1/2 , 7p 3/2 , 8p 1/2 , and 8p 3/2 removal energies for which experimental measurements are not available. The hyperfine constants A are determined for the low-lying levels up to n = 7. The quadratic Stark effect on hyperfine structure levels of 43 Ca + ground state is investigated. These calculations provide recommended values critically evaluated for their accuracy for a number of Ca + atomic properties for use in planning and analysis of various experiments as well as theoretical modeling.

show abstract

Section: Energy Levelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca+

Safronova

2011

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…Two-level systems manipulated by electromagnetic waves are the fundamental building blocks in many applications, such as nuclear magnetic resonance (NMR) [1] and electron paramagnetic resonance (EPR) microscopy, atomic clocks [2,3] and interferometers [4,5], magnetometry with atoms [6] or NV centers in diamonds [7] and quantum information processing with atoms, ions, quantum dots or superconducting qubits [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Damping of local Rabi oscillations in the presence of thermal motion

et al. 2013

View full text Add to dashboard Cite

We investigate both theoretically and experimentally the effect of thermal motion of laser cooled atoms on the coherence of Rabi oscillations induced by an inhomogeneous driving field. The experimental results are in excellent agreement with the derived analytical expressions. For freely falling atoms with negligible collisions, as those used in our experiment, we find that the amplitude of the Rabi oscillations decays with time t as exp[−(t/τ ) 4 ] , where the coherence time τ drops with increasing temperature and field gradient. We discuss the consequences of these results regarding the fidelity of Rabi rotations of atomic qubits. We also show that the process is equivalent to the loss of coherence of atoms undergoing a Ramsey sequence in the presence of static magnetic field gradients -a common situation in many applications. In addition, our results are relevant for determining the resolution when utilizing atoms as field probes. Using numerical calculations, our model can be easily extended to situations in which the atoms are confined by a potential or to situations where collisions are important.

show abstract

“…The present relative standard uncertainty of the Cs microwave frequency standard is approximately 4 × 10 −16 [1]. The operation of atomic clocks is generally carried out at room temperature, whereas the definition of the second refers to the clock transition in an atom at absolute zero.…”

Section: Introductionmentioning

confidence: 99%

“…Significant recent progress in optical spectroscopy and measurement techniques has led to the achievement of relative standard uncertainties in optical frequency standards that are comparable to the Cs microwave benchmark. In 2006, the International Committee for Weights and Measures (CIPM) recommended that the following transitions frequencies be used as secondary representations of the second [5]: ground-state hyperfine microwave transition in 87 Rb [6], [7], 5s 2 S 1/2 − 4d 2 D 5/2 optical transition of the 88 Sr + ion [8], [9], 5d 10 6s 2 S 1/2 (F = 0) − 5d 9 6s 2 2 D 5/2 (F = 2) optical transition in 199 Hg + ion [10], [11], 6s 2 S 1/2 (F = 0) − 5d 2 D 5/2 (F = 2) optical transition in 171 Yb + ion [12], [13] and 5s 2 1 S 0 − 5s5p 3 P 0 transition in 87 Sr neutral atom [14], 1 Email: msafrono@udel.edu [15], [16]. With better stability and accuracy, as well as extremely low systematic perturbations, such optical frequency standards can reach a systematic fractional uncertainty of order 10 −18 [9], [17].…”

Section: Introductionmentioning

confidence: 99%

Black-body radiation shifts and theoretical contributions to atomic clock research

Safronova

Jiang

Arora

et al. 2010

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

View full text Add to dashboard Cite

Abstract-A review of theoretical calculations of black-body radiation (BBR) shifts in various systems of interest to atomic clock research in presented. Calculations for monovalent systems, such as Ca + , Sr + , and Rb are carried out using a relativistic all-order single-double method, where all single and double excitations of the Dirac-Fock wave function are included to all orders of perturbation theory. A recently developed method for accurate calculations of BBR shifts in divalent atoms such as Sr is discussed. This approach combines the relativistic all-order method and the configuration interaction method. The evaluation of uncertainties in theoretical values of BBR shifts is discussed in detail.

show abstract

NIST Primary Frequency Standards and the Realization of the SI Second

Cited by 46 publications

References 57 publications

Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca+

Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca+

Damping of local Rabi oscillations in the presence of thermal motion

Black-body radiation shifts and theoretical contributions to atomic clock research

Contact Info

Product

Resources

About