DR. SUBHADEEP DE

Duration for 9 192 631 770 electronic oscillations between the doublet hyperfine ground state of caesium atoms is internationally defined as the SI second since 1967. CSIR-NPL, the national metrological institute in India, is custodian of maintaining the national time namely the Indian Standard Time (IST) as per the international standard. In last two decades, the laser cooling and different trapping techniques has reached to a high level of sophistication, which allows precise controlling of the atoms in a well characterized environment. This enables the researcher to build more and more accurate atomic clocks which have wide range of applications in exploring fundamental science and also in sophisticated modern technologies. This boosts us developing accurate atomic clocks which will enable us in time keeping at a level of 1 s accuracy over the age of the universe. We have successfully developed caesium fountain which is currently operational with an accuracy of 2¿10-15 and contributing for accurate time keeping at the international level. Recently, we have started developing an ytterbium-ion optical clock which may reach to an accuracy of 1 part in 1018. In this lecture, the speaker will give an overview about the IST generation & dissemination, current status in caesium fountains and development of the upcoming ytterbium-ion optical clock.