Jul 17 – 22, 2022
Royal Conservatory of Music, Toronto
America/Toronto timezone

Ultra-high vacuum chamber development for a Sr optical lattice clock with a Laguerre-Gaussian trapping geometry

Jul 20, 2022, 5:00 PM
1h 30m
Hart House (Hart House)

Hart House

Hart House

7 Hart House Cir, Toronto, ON M5S 3H3
Poster presentation Precision measurement and tests of fundamental physics Poster session


Strontium optical lattice clocks (OLC) are a promising instrument for applications ranging from the redefinition of the second in the international system to geodesy and fundamental physics, for instance, dark matter detection, variation of fundamental constants, or general relativity tests. LNE-SYRTE, Observatoire de Paris operates two Sr OLCs with a systematic uncertainty on the order of $10^{-17}$, mostly limited by the inhomogeneous thermal distribution of the vacuum chamber inducing black body radiation (BBR) shift, but also by cold collisions between the atoms trapped in each site of the optical lattice.
Aiming to improve the characterization of systematic effects in optical lattice clocks below $10^{-18}$, we propose the implementation of Laguerre-Gaussian modes (LG$_{pl}$) to shape a multi-site trap in the 1D optical lattice of a Sr OLC. Hence reducing the density of atoms, while preserving the advantages of 1D lattices such as amplified power and spatial purity of the modes, unlike 3D optical lattices or tweezers. Quantitatively, the trapping potential in an LG$_{0l}$ mode is given by:
$U_{0l}(r,\varphi,z)=-U_0 e^{\frac{-2r^2}{w^2(z)}}\cos^2\left[kz-\psi_l(z)\right]\left(\frac{2r^2}{w^2(z)}\right)^{|l|}\cos^2(l\varphi)$
where $U_0 = \alpha_d I_0$, with $\alpha_d$ the atomic polarizability and $I_0$ the intra-cavity of the trapping light.
In this work, using a liquid crystal on silicon spatial light modulator (SLM), we demonstrate the generation of LG$_{0l}$ modes with $l$ up to 4, and the injection of these modes into an optical cavity placed in a new copper vacuum chamber. A Pound-Drever-Hall (PDH) scheme is then used to lock the cavity length to the LG$_{0l=0,1,2,3,4}$ modes. Trapping depths up to 39$E_r$ for an LG$_{04}$ were obtained, a priori making it possible to implement LG lattices within the clock sequence.
In addition, for limiting conductive and radiative exchanges between the experimental system and the laboratory, the thermal design of the new setup comprises an Ultra-High Vacuum (UHV) chamber that is also placed in a primary vacuum environment. The new thermal conditions will allow better control and determination of the contribution of the BBR to the clock transition $^1 S_0 - ^3P_0$ at a fractional uncertainty below $10^{-18}$.

Presenter name Miguel Angel Cifuentes Marin
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Primary authors

Miguel Angel Cifuentes Marin (SYRTE - Observatoire de Paris) Jérôme Lodewyck (LNE-SYRTE, Observatoire de Paris) Rodolphe Letargat (LNE-SYRTE Observatoire de Paris) Haosen Shang (LNE-SYRTE Observatoire de Paris) Yannick Foucault (LNE-SYRTE Observatoire de Paris)

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