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In ion optical clock systems, the motional effects of trapped ions are critical factors in determining clock performance and currently represent key limitations in achieving lower uncertainty across different ion-based optical clocks. Building on the first liquid nitrogen-cooled Ca$^+$ ion optical clock [PhysRevApplied.17.034041], we have developed a new physical system for a second Ca$^+$ ion optical clock and made significant improvements to its ion trapping apparatus. These improvements primarily focus on two aspects: First, we designed and implemented an active stabilization system for the RF voltage, which stabilizes the induced RF signal on the compensation electrodes by adjusting the RF source amplitude in real time. This approach effectively suppressed long-term drifts in the radial secular motion frequencies to less than 1 kHz, achieving stabilized values of $\omega_x = 2\pi \times 3.522(2)\,\mathrm{MHz}$ and $\omega_y = 2\pi \times 3.386(2)\,\mathrm{MHz}$. The induced RF signal was stabilized at 59 121.43(12) µV, demonstrating the high precision of the stabilization system. Second, we optimized the application of compensation voltages by integrating the vertical compensation electrodes directly onto the ion trap structure. This refinement enabled us to suppress excess micromotion in all three mutually orthogonal directions to an even lower level. With the RF trapping frequency tuned close to the magic trapping condition of the clock transition, we further evaluated the excess micromotion-induced frequency shift in the optical clock to be $2(1) \times 10^{-19}$. To quantitatively assess the secular motion of the trapped ion, we performed sideband spectroscopy on the radial and axial motional modes, measuring both red and blue sidebands. From these measurements, we accurately determined the mean phonon number in the three motional modes after Doppler cooling, corresponding to an average ion temperature of $0.78(39)\,\mathrm{mK}$, which is close to the Doppler cooling limit. The corresponding second-order Doppler shift was evaluated to be $-(2.71 \pm 1.36) \times 10^{-18}$. The long-term stability of the radial secular motion frequency provides favorable conditions for implementing three-dimensional sideband cooling in future experiments, which will further reduce the second-order Doppler shift. These advancements not only enhance the overall stability of the optical clock but also lay the foundation for reducing its systematic uncertainty to the $10^{-19}$ level.
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Keywords:
- Ca+ion optical clock /
- cryogenic /
- secular motion /
- excess micromotion
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[1] Chen J 2009 Chinese Science Bulletin 54 348
[2] Dimarcq N, Gertsvolf M, Mileti G, Bize S, Oates C W, Peik E, Calonico D, Ido T, Tavella P, Meynadier F, Petit G, Panfilo G, Bartholomew J, Defraigne P, Donley E A, Hedekvist P O, Sesia I, Wouters M, Dubé P, Fang F, Levi F, Lodewyck J, Margolis H S, Newell D, Slyusarev S, Weyers S, Uzan J P, Yasuda M, Yu D H, Rieck C, Schnatz H, Hanado Y, Fujieda M, Pottie P E, Hanssen J, Malimon A, Ashby N 2024 Metrologia 61 012001
[3] Riehle F, Gill P, Arias F, Robertsson L 2018 Metrologia 55 188
[4] Gill P 2016 Journal of Physics: Conference Series 723 012053
[5] Takano T, Takamoto M, Ushijima I, Ohmae N, Akatsuka T, Yamaguchi A, Kuroishi Y, Munekane H, Miyahara B, Katori H 2016 Nature Photonics 10 662
[6] Schuldt T, Gohlke M, Oswald M, Wüst J, Blomberg T, Döringshoff K, Bawamia A, Wicht A, Lezius M, Voss K, Krutzik M, Herrmann S, Kovalchuk E, Peters A, Braxmaier C 2021 GPS Solutions 25 83
[7] Takamoto M, Ushijima I, Ohmae N, Yahagi T, Kokado K, Shinkai H, Katori H 2020 Nature Photonics 14 411
[8] Sanner C, Huntemann N, Lange R, Tamm C, Peik E, Safronova M S, Porsev S G 2019 Nature 567 204
[9] Mehlstäubler T E, Grosche G, Lisdat C, Schmidt P O, Denker H 2018 Reports on Progress in Physics 81 064401
[10] Gilmore K A, Affolter M, Lewis-Swan R J, Barberena D, Jordan E, Rey A M, Bollinger J J 2021 Science 373 673
[11] Huntemann N, Lipphardt B, Tamm C, Gerginov V, Weyers S, Peik E 2014 Phys. Rev. Lett. 113 210802
[12] Chou C W, Hume D B, Rosenband T, Wineland D J 2010 Science 329 1630
[13] Filzinger M, Dörscher S, Lange R, Klose J, Steinel M, Benkler E, Peik E, Lisdat C, Huntemann N 2023 Phys. Rev. Lett. 130 253001
[14] Kolkowitz S, Pikovski I, Langellier N, Lukin M D, Walsworth R L, Ye J 2016 Phys. Rev. D 94 124043
[15] McGrew W F, Zhang X, Fasano R J, Schäffer S A, Beloy K, Nicolodi D, Brown R C, Hinkley N, Milani G, Schioppo M, Yoon T H, Ludlow A D 2018 Nature 564 87
[16] Aeppli A, Kim K, Warfield W, Safronova M S, Ye J 2024 Phys. Rev. Lett. 133 023401
[17] Ma Z Y, Deng K, Wang Z Y, Wei W Z, Hao P, Zhang H X, Pang L R, Wang B, Wu F F, Liu H L, Yuan W H, Chang J L, Zhang J X, Wu Q Y, Zhang J, Lu Z H 2024 Phys. Rev. Appl. 21 044017
[18] Li J, Cui X Y, Jia Z P, Kong D Q, Yu H W, Zhu X Q, Liu X Y, Wang D Z, Zhang X, Huang X Y, Zhu M Y, Yang Y M, Hu Y, Liu X P, Zhai X M, Liu P, Jiang X, Xu P, Dai H N, Chen Y A, Pan J W 2024 Metrologia 61 015006
[19] Ushijima I, Takamoto M, Das M, Ohkubo T, Katori H 2015 Nature Photonics 9 185
[20] Brewer S M, Chen J S, Hankin A M, Clements E R, Chou C W, Wineland D J, Hume D B, Leibrandt D R 2019 Phys. Rev. Lett. 123 033201
[21] Huang Y, Zhang B, Zeng M, Hao Y, Ma Z, Zhang H, Guan H, Chen Z, Wang M, Gao K 2022 Phys. Rev. Appl. 17 034041
[22] Tofful A, Baynham C F A, Curtis E A, Parsons A O, Robertson B I, Schioppo M, Tunesi J, Margolis H S, Hendricks R J, Whale J, Thompson R C, Godun R M 2024 Metrologia 61 045001
[23] Lu B K, Sun Z, Yang T, Lin Y G, Wang Q, Li Y, Meng F, Lin B K, Li T C, Fang Z J 2022 Chinese Physics Letters 39 080601
[24] Zhiqiang Z, Arnold K J, Kaewuam R, Barrett M D 2023 Science Advances 9 eadg1971
[25] Lu X, Guo F, Wang Y, Xu Q, Zhou C, Xia J, Wu W, Chang H 2023 Metrologia 60 015008
[26] Arnold K J, Kaewuam R, Roy A, Tan T R, Barrett M D 2018 Nature Communications 9 1650
[27] Dubé P, Madej A A, Tibbo M, Bernard J E 2014 Phys. Rev. Lett. 112 173002
[28] Huang Y, Guan H, Zeng M, Tang L, Gao K 2019 Phys. Rev. A 99 011401
[29] Porsev S G, Derevianko A 2006 Phys. Rev. A 74 020502
[30] Angstmann E J, Dzuba V A, Flambaum V V 2006 Phys. Rev. Lett. 97 040802
[31] Zeng M, Huang Y, Zhang B, Hao Y, Ma Z, Hu R, Zhang H, Chen Z, Wang M, Guan H, Gao K 2023 Phys. Rev. Appl. 19 064004
[32] Bothwell T, Kedar D, Oelker E, Robinson J M, Bromley S L, Tew W L, Ye J, Kennedy C J 2019 Metrologia 56 065004
[33] Doležal M, Balling P, Nisbet-Jones P B R, King S A, Jones J M, Klein H A, Gill P, Lindvall T, Wallin A E, Merimaa M, Tamm C, Sanner C, Huntemann N, Scharnhorst N, Leroux I D, Schmidt P O, Burgermeister T, Mehlstäubler T E, Peik E 2015 Metrologia 52 842
[34] Zeng M, Huang Y, Zhang B, Ma Z, Hao Y, Hu R, Zhang H, Guan H, Gao K 2023 Chinese Physics B 32 113701
[35] Berkeland D J, Miller J D, Bergquist J C, Itano W M, Wineland D J 1998 Journal of Applied Physics 83 5025
[36] Chen J S, Brewer S M, Chou C W, Wineland D J, Leibrandt D R, Hume D B 2017 Phys. Rev. Lett. 118 053002
[37] Keller J, Partner H L, Burgermeister T, Mehlstäubler T E 2015 Journal of Applied Physics 118 104501
[38] Wineland D J, Monroe C, Itano W M, Leibfried D, King B E, Meekhof D M 1998 Journal of research of the National Institute of Standards and Technology 103 259
[39] James D F V 1998 Applied Physics B 66 181
[40] Zhang B, Huang Y, Hao Y, Zhang H, Zeng M, Guan H, Gao K 2020 Journal of Applied Physics 128 143105
[41] Zhang B, Huang Y, Zhang H, Hao Y, Zeng M, Guan H, Gao K 2020 Chinese Physics B 29 074209
[42] Dubé P, Madej A A, Zhou Z, Bernard J E 2013 Phys. Rev. A 87 023806
[43] Huntemann N, Sanner C, Lipphardt B, Tamm C, Peik E 2016 Phys. Rev. Lett. 116 063001
[44] Chou C W, Hume D B, Koelemeij J C J, Wineland D J, Rosenband T 2010 Phys. Rev. Lett. 104 070802
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