Combined optical–infrared single-ion frequency standard

Abstract

A combined infrared-optical frequency-standard scheme has been demonstrated with a single ion of ytterbium. The optical (2)S(1/2)-(2)D(5/2) reference transition at 411 nm and the infrared (2)F(7/2)-(2)D(5/2) 3.43-microm transition were driven sequentially. The structure of the infrared (2)F(7/2)-(2)D(5/2) reference transition at 3.43 microm has also been studied. Infrared transition linewidths of 300 kHz were observed. The output of a Nd:YAG laser and an extended-cavity diode laser were difference-frequency mixed in a crystal of AgGaS(2) to produce narrow-linewidth light at 3.43 microm . Both lasers were frequency stabilized to high-finesse reference cavities.

Calculations of the relativistic effects in many-electron atoms and space-time variation of fundamental constants

“…We present in Table IV relativistic shifts of frequencies of some atomic transitions which are used or proposed as optical frequency standards. These include the strongly forbidden E1 transition in Ca I [13] and E2 transitions in Sr II [14], Yb II [15] and Hg II [16]. There are many other atoms which are being studied as possible frequency standards but which are not included in the table.…”

“…Single-electron states of a valence electron calculated in a non-local potential (15) are often called Brueckner orbitals.…”

Lifetime measurements and calculations in singly ionized ytterbium

“…The ytterbium ion has attracted much attention from physicists in recent years for several reasons. It has special interest for atomic clocks and trapped-ion frequency standards in relation to the structure of the low-lying levels giving rise to optical, infrared or microwave frequency standards (Tamm et al 1995, Fisk et al 1995, Gill et al 1995, Taylor et al 1998. Among the transitions of particular interest, the electric octupole 2 S 1/2 -2 F 7/2 467 nm transition, belonging to the isotopes 172 or 171 of Yb + , which has a lifetime of around 10 years, has attracted special attention, both experimentally (Roberts et al 1997(Roberts et al , 2000 and theoretically .…”

High-resolution, high-accuracy spectroscopy of trapped ions

“…Therefore, many groups are working on optical frequency standards. The laser-cooled stored ion efforts include trapped 172Yb+ at 411 nm [44] and 3.43 pm [45], 171Yb+ at 435 nm [46], 88Sr+ at 674 nm [47,48], 138Ba+ at 12.5 pm [49], *Oca+ at 729 nm [50-521, '''In+ at 237 nm [53,54], and lg9Hg+ at 282 nm [55].…”