Measurement of the $^{199}\mathrm{Hg}^{+}$ $5{d}^{9}6{s}^{2}\text{ }^{2}D_{5/2}$ Electric Quadrupole Moment and a Constraint on the Quadrupole Shift

Measurement of the ${}^{199}{Hg}^{+}$ $5 d^{9} 6 s^{2} {}^{2}D_{5 / 2}$ Electric Quadrupole Moment and a Constraint on the Quadrupole Shift

W. H. Oskay, W. M. Itano, and J. C. Bergquist

Phys. Rev. Lett. 94, 163001 – Published 26 April 2005

Abstract

The electric-quadrupole moment of the state is measured to be . This value was determined by measuring the frequency of the optical clock transition for different applied electric-field gradients. An isolated, mechanically stable optical cavity provides a frequency reference for the measurement. We compare the results with theoretical calculations and discuss the implications for the accuracy of an atomic clock based upon this transition. We now expect that the frequency shift caused by the interaction of the quadrupole moment with stray electric-field gradients will not limit the accuracy of the optical clock at the level.