National Physical Laboratory (NPL), New Delhi has reported the successful development of the first and only Cs fountain clock in India. This is one of the most accurate clocks on Earth, based on laser cooled atoms of Cs. Such a clock also acts as primary frequency standard. In this fountain, trapping of about 10 million atoms and cooling these to a few μK above absolute zero, has been demonstrated. These atoms could be launched up to a meter and the return signal is detected by measuring the fluorescence. During the flight, these cold atoms interact with a synthesized microwave signal twice and this leads to its operation as an ultraprecise clock. The first clock signal (Ramsey Fringes) was recently demonstrated at NPL.
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