Concept of a thorium-229 based nuclear optical clock.
A nuclear clock or nuclear optical clock is a notional clock that would use the frequency of a nuclear transition as its reference frequency,[1] in the same manner as an atomic clock uses the frequency of an electronic transition in an atom's shell. Such a clock is expected to be more accurate than the best current atomic clocks by a factor of about 10, with an achievable accuracy approaching the 10−19 level.[2]
The only nuclear state suitable for the development of a nuclear clock using existing technology is thorium-229m, a nuclear isomer of thorium-229 and the lowest-energy nuclear isomer known. With an energy of 8.35574(3) eV,[3][4] this corresponds to a wavelength of 148.3821(5) nm in the vacuum ultraviolet region, making it accessible to laser excitation.[5][6]
^Peik, Ekkehard; Tamm, Christian (15 January 2003). "Nuclear laser spectroscopy of the 3.5 eV transition in 229Th" (PDF). Europhysics Letters. 61 (2): 181–186. Bibcode:2003EL.....61..181P. doi:10.1209/epl/i2003-00210-x. S2CID 250818523. Archived (PDF) from the original on 2024-04-11. Retrieved 2019-03-17.
^C. Campbell; et al. (2012). "A single ion nuclear clock for metrology at the 19th decimal place". Physical Review Letters. 108 (12) 120802: 120802. arXiv:1110.2490. Bibcode:2012PhRvL.108l0802C. doi:10.1103/PhysRevLett.108.120802. PMID 22540568. S2CID 40863227.
^Thirolf, Peter (April 29, 2024). "Shedding Light on the Thorium-229 Nuclear Clock Isomer". Physics. Vol. 17. doi:10.1103/Physics.17.71.
^Tiedau, J.; Okhapkin, M. V.; Zhang, K.; Thielking, J.; Zitzer, G.; Peik, E.; et al. (29 April 2024). "Laser Excitation of the Th-229 Nucleus" (PDF). Physical Review Letters. 132 (18) 182501: 182501. Bibcode:2024PhRvL.132r2501T. doi:10.1103/PhysRevLett.132.182501. PMID 38759160. The nuclear resonance for the Th4+ ions in Th:CaF2 is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum.
^Cite error: The named reference WenseReview was invoked but never defined (see the help page).
^Miller, Johanna L (1 June 2024). "Slow-motion spectroscopy paves the way for a nuclear clock". Physics Today. Vol. 77, no. 6. pp. 12–14. doi:10.1063/pt.kvtv.jxde.
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