@article { ISI:000548140000001,
title = {Branching fractions for P-3/2 decays in Ba+},
journal = {Phys. Rev. A},
volume = {101},
number = {6},
year = {2020},
month = {JUN 24},
pages = {062515},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {Branching fractions for decays from the P-3/2 level in B-138 at have been measured with a single laser-cooled ion. Decay probabilities to S-1/2, D-3/2, and D-5/2 are determined to be 0.741716(71), 0.028031(23), and 0.230253(61), respectively, which are an order-of-magnitude improvement over previous results. Our methodology only involves optical pumping and state detection, and is hence relatively free of systematic effects. Measurements are carried out in two different ways to check for consistency. Our analysis also includes a measurement of the D-5/2 lifetime, for which we obtain 30.14(40) s.},
issn = {1050-2947},
doi = {10.1103/PhysRevA.101.062515},
author = {Zhang, Zhiqiang and Arnold, K. J. and Chanu, S. R. and Kaewuam, R. and Safronova, M. S. and Barrett, M. D.}
}
@article { ISI:000527491100005,
title = {Magic wavelength of the Ba-138(+) 6s S-2(1/2)-5d D-2(5/2) clock transition},
journal = {Phys. Rev. A},
volume = {101},
number = {4},
year = {2020},
month = {APR 22},
pages = {042507},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {The zero crossing of the dynamic differential scalar polarizability of the S-1/2 - D-5/2 clock transition in Ba-138(+) has been determined to be 459.1614(28) THz. Together with previously determined matrix elements and branching ratios, this tightly constrains the dynamic differential scalar polarizability of the clock transition over a large wavelength range (greater than or similar to 700 nm). In particular, it allows an estimate of the blackbody radiation shift of the clock transition at room temperature.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.101.042507},
author = {Chanu, S. R. and Koh, V. P. W. and Arnold, K. J. and Kaewuam, R. and Tan, T. R. and Zhang, Zhiqiang and Safronova, M. S. and Barrett, M. D.}
}
@article {ISI:000455814100005,
title = {Dynamic polarizability measurements with Lu-176(+)},
journal = {Phys. Rev. A},
volume = {99},
number = {1},
year = {2019},
month = {JAN 15},
pages = {012510},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {We measure the differential polarizability of the Lu-176(+) S-1(0) <-> D-3(1) clock transition at multiple wavelengths. This experimentally characterizes the differential dynamic polarizability for frequencies up to 372 THz and allows an experimental determination of the dynamic correction to the blackbody radiation shift for the clock transition. In addition, measurements at the near resonant wavelengths of 598 and 646 nm determine the two dominant contributions to the differential dynamic polarizability below 372 THz. These additional measurements are carried out by two independent methods to verify the validity of our methodology. We also carry out a theoretical calculation of the polarizabilities using the hybrid method that combines the configuration interaction (CI) and the coupled-cluster approaches, incorporating for the first time quadratic nonlinear terms and partial triple excitations in the coupled-cluster calculations. The experimental measurements of the vertical bar < D-3(1)parallel to r parallel to P-3(J)>vertical bar matrix elements provide high-precision benchmarks for this theoretical approach.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.99.012510},
author = {Arnold, K. J. and Kaewuam, R. and Tan, T. R. and Porsev, S. G. and Safronova, M. S. and Barrett, M. D.}
}
@article {ISI:000483578600012,
title = {Measurements of the branching ratios for 6P(1/2) decays in Ba-138(+)},
journal = {Phys. Rev. A},
volume = {100},
number = {3},
year = {2019},
month = {SEP 3},
pages = {032503},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {Measurement of the branching ratios for 6P(1/2) decays to 6S(1/2) and 5D(3/2) in Ba-138(+) are reported with the decay probability from 6P(1/2) to 5D(3/2) measured to be p = 0.268177 +/- (37)(stat)-(20)(sys). This result differs from a recent report by 12 sigma. A detailed account of systematics is given, and the likely source of the discrepancy is identified. The new value of the branching reported here is combined with previous experimental results to give a new estimate of tau = 7.855(10) ns for the 6P(1/2) lifetime. In addition, ratios of matrix elements calculated from theory are combined with experimental results to provide improved theoretical estimates of the 6P(3/2) lifetime and the associated matrix elements.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.100.032503},
author = {Arnold, K. J. and Chanu, S. R. and Kaewuam, R. and Tan, T. R. and Yeo, L. and Zhang, Zhiqiang and Safronova, M. S. and Barrett, M. D.}
}
@article { ISI:000492332900006,
title = {Polarizability assessments of ion-based optical clocks},
journal = {Phys. Rev. A},
volume = {100},
number = {4},
year = {2019},
month = {OCT 24},
pages = {043418},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {It is shown that the dynamic differential scalar polarizability of the S-1/2 - D-5/2 transition in Ba-138(+) can be determined to an inaccuracy below 0.5\% across a wide wavelength range (lambda > 700 nm). This can be achieved using measurements for which accurate determination of laser intensity is not required, and most of the required measurements are already in the literature. Measurement of a laser-induced ac-Stark shift of the clock transition would then provide an in situ measurement of the laser{\textquoteright}s intensity to the same 0.5\% level of inaccuracy, which is not easily achieved by other means. This would allow accurate polarizability measurements for clock transitions in other ions, through comparison with Ba-138(+). The approach would be equally applicable to Sr+ and Ca+, with the latter being immediately applicable to Al+/Ca+ quantum logic clocks.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.100.043418},
author = {Barrett, M. D. and Arnold, K. J. and Safronova, M. S.}
}
@article {ISI:000479034100005,
title = {Suppressing Inhomogeneous Broadening in a Lutetium Multi-ion Optical Clock},
journal = {Phys. Rev. Lett.},
volume = {123},
number = {6},
year = {2019},
month = {AUG 7},
pages = {063201},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {We demonstrate precision measurement and control of inhomogeneous broadening in a multi-ion clock consisting of three Lu-176(+) ions. Microwave spectroscopy between hyperfine states in the D-3(1) level is used to characterize differential systematic shifts between ions, most notably those associated with the electric quadrupole moment. By appropriate alignment of the magnetic field, we demonstrate suppression of these effects to the similar to 10(-17) level relative to the S-1(0) <-> D-3(1) optical transition frequency. Correlation spectroscopy on the optical transition demonstrates the feasibility of a 10-s Ramsey interrogation in the three ion configuration with a corresponding projection noise limited stability of sigma(tau) = 8.2 x 10(-17)/root tau.},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.123.063201},
author = {Tan, T. R. and Kaewuam, R. and Arnold, K. J. and Chanu, S. R. and Zhang, Zhiqiang and Safronova, M. S. and Barrett, M. D.}
}