Direct laser cooling Al+ ions optical clocks

Abstract

Al${}^{+}$ ions optical clock is a very promising optical frequency standard candidate due to its extremely small blackbody radiation shift. It has been successfully demonstrated with indirect cooled, quantum-logic-based spectroscopy technique. Its accuracy is limited by second-order Doppler shift, and its stability is limited by the number of ions that can be probed in quantum logic processing. We propose a direct laser cooling scheme of Al${}^{+}$ ions optical clocks where both the stability and accuracy of the clocks are greatly improved. In the proposed scheme, two Al${}^{+}$ ions traps are utilized. The first trap is used to trap a large number of Al${}^{+}$ ions to improve the stability of the clock laser, while the second trap is used to trap a single Al${}^{+}$ ions to provide the ultimate accuracy. Both traps are cooled with a continuous wave 167 nm laser. The expected clock laser stability can reach $9.0\times 10^{-17}/\sqrt{\tau }$. For the second trap, in addition to 167 nm laser Doppler cooling, a second stage pulsed 234 nm two-photon cooling laser is utilized to further improve the accuracy of the clock laser. The total systematic uncertainty can be reduced to about $1\times 10^{-18}$. The proposed Al${}^{+}$ ions optical clock has the potential to become the most accurate and stable optical clock.

arXiv comment17 pages, 2 figures

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Cited by in corpus (2)

• Towards a Transportable Aluminium Ion Quantum Logic Optical Clock
• Investigating the $4D_{3/2}|3,\pm 2⟩$--$4D_{5/2}|3,\pm 2⟩$ transition in Nb${}^{4+}$ for a THz atomic clock