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Turquoise magic wavelength of the 87Sr clock transition

G. Kestler1, R.J. Sedlik1, E.C. Trapp2, M.S. Safronova3, and J.T. Barreiro1,*

  • *Contact author: barreiro@ucsd.edu
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Phys. Rev. Applied 25, 014053 – Published 22 January, 2026

DOI: https://doi.org/10.1103/rp9f-664g

Abstract

Optical lattice clocks of fermionic strontium offer a versatile platform for probing fundamental physics and developing quantum technologies. The bivalent electronic structure of strontium gives rise to a doubly forbidden atomic transition that is accessible due to hyperfine mixing in fermionic strontium-87, thus resulting in a submillihertz natural linewidth. Currently, the most accurate optical lattice clocks operate on this narrow transition by tightly trapping strontium-87 atoms in a magic optical lattice at 813 nm. Magic wavelengths occur where the Stark shifts of both the ground and excited states are equal, thus eliminating any position- and intensity-dependent broadening of the corresponding transition. Theoretical calculations of the electronic structure of strontium-87 have also predicted another magic wavelength of the clock transition at 497.01(57) nm. In this work, we experimentally measure the magic wavelength to be 497.4364(4) nm. Compared to the 813-nm magic wavelength, 497 nm is closer to the strong 461-nm dipolar transition of strontium, resulting in an order-of-magnitude increase in atomic polarizability and deeper traps with less optical power. The proximity to the 461-nm transition also leads to an enhanced sensitivity of 334(10) Hz/(nm ER) at the magic wavelength.

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Phys. Rev. Applied 25, 014053– Published 22 January, 2026
  • Received 9 July 2025
  • Revised 22 October 2025
  • Accepted 22 December 2025
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