Optical Frequency Standard

Contact:
Dr. S. Panja / Dr. S. De
Room: 132, Main Building
CSIR – NPL, Dr. K. S. Krishnan Marg
New Delhi – 110012
Email: panjas@mail.nplindia.org
subhadeep@mail.nplindia.orgorg
Ph: +91 4560 9229
Fax: +91 4560 9240

Optical Frequency Standard

An optical frequency standard is based on optically probed narrow line-width electronic transition of some atoms or ions. An optical clock has much higher accuracy as it operates at few hundred THz frequency region compared to the conventional microwave atomic clocks. In NPLI, we are developing an optical frequency standard based on an ultra-narrow optical transition in single trapped Ytterbium ion (171Yb+). For 171 Yb+ the lowest lying excited state is 2D3/2 which decays to the 2S1/2 ground state via an electric quadrupole transition at 435.5 nm. The long lived 2D3/2 state has natural decay time of several years, which leads to an extremely narrow natural line width (3.1 Hz) of that transition. A Paul trap will be used to trap a single 171Yb+ and the temperature of the ion will be reduced to few micro Kelvin by laser cooling technique. A closed laser cooling scheme using 369.5 nm transition can be realized by implying two additional lasers at 935 nm and 638 nm for repumping. Finally fluorescence at 435.5 nm is will be used to drive the 2S1/2 (F =0) - 2D3/2 (F=2) clock transition, and the ion state will be determined by electron shelving technique.

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