Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Oscillating quadrupole effects in high precision metrology   The influence of oscillating quadrupole fields on atomic energy levels is
examined theoretically and general expressions for the quadrupole matrix
elements are given. The results are relevant to any ion-based clock in which
one of the clock states supports a quadrupole moment. Clock shifts are
estimated for $^{176}$Lu$^+$ and indicate that coupling to the quadrupole field
would not be a limitation to clock accuracy at the $\lesssim10^{-19}$ level.
Nevertheless, a method is suggested that would allow this shift to be
calibrated. This method utilises a resonant quadrupole coupling that enables
the quadrupole moment of the atom to be measured. A proof-of-principle
demonstration is given using $^{138}$Ba$^+$, in which the quadrupole moment of
the $D_{5/2}$ state is estimated to be $\Theta=3.229(89) e a_0^2$.

9
The categories of this paper are: nlin
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn