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R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

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T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

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St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

D. Akamatsu, H. Inaba, K. Hosaka, M. Yasuda, A. Onae, T. Suzuyama, M. Amemiya, and F.-L. Hong, “Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb,” Appl. Phys. Express 7(1), 012401 (2014).

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A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

A. A. Madej, P. Dubé, Z. Zhou, J. E. Bernard, and M. Gertsvolf, “88Sr+ 445-THz single-ion reference at the 10-17 level via control and cancellation of systematic uncertainties and its measurement against the SI second,” Phys. Rev. Lett. 109(20), 203002 (2012).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10(-18) level,” Nature 506(7486), 71–75 (2014).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10(-18) level,” Nature 506(7486), 71–75 (2014).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10(-18) level,” Nature 506(7486), 71–75 (2014).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10(-18) level,” Nature 506(7486), 71–75 (2014).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

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A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

A. A. Madej, P. Dubé, Z. Zhou, J. E. Bernard, and M. Gertsvolf, “88Sr+ 445-THz single-ion reference at the 10-17 level via control and cancellation of systematic uncertainties and its measurement against the SI second,” Phys. Rev. Lett. 109(20), 203002 (2012).

T. Middelmann, S. Falke, C. Lisdat, and U. Sterr, “High accuracy correction of blackbody radiation shift in an optical lattice clock,” Phys. Rev. Lett. 109(26), 263004 (2012).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

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A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

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Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

A. A. Madej, P. Dubé, Z. Zhou, J. E. Bernard, and M. Gertsvolf, “88Sr+ 445-THz single-ion reference at the 10-17 level via control and cancellation of systematic uncertainties and its measurement against the SI second,” Phys. Rev. Lett. 109(20), 203002 (2012).

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J. Azoubib, M. Granveaud, and B. Guinot, “Estimation of the scale unit duration of time scales,” Metrologia 13(3), 87–93 (1977).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

J. Azoubib, M. Granveaud, and B. Guinot, “Estimation of the scale unit duration of time scales,” Metrologia 13(3), 87–93 (1977).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

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St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

T. Ido, H. Hachisu, F. Nakagawa, and Y. Hanado, “Rapid evaluation of time scale using an optical clock,” J. Phys. Conf. Ser. 723, 012041 (2016).

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Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

D. Akamatsu, H. Inaba, K. Hosaka, M. Yasuda, A. Onae, T. Suzuyama, M. Amemiya, and F.-L. Hong, “Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb,” Appl. Phys. Express 7(1), 012401 (2014).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

D. Akamatsu, H. Inaba, K. Hosaka, M. Yasuda, A. Onae, T. Suzuyama, M. Amemiya, and F.-L. Hong, “Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb,” Appl. Phys. Express 7(1), 012401 (2014).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

H. Hachisu, G. Petit, and T. Ido, “Absolute frequency measurement with uncertainty below 1×10−15 using International Atomic Time,” Appl. Phys. B 123(1), 34 (2017).

T. Ido, H. Hachisu, F. Nakagawa, and Y. Hanado, “Rapid evaluation of time scale using an optical clock,” J. Phys. Conf. Ser. 723, 012041 (2016).

H. Hachisu and T. Ido, “Intermittent optical frequency measurements to reduce the dead time uncertainty of frequency link,” Jpn. J. Appl. Phys. 54(11), 112401 (2015).

A. Yamaguchi, N. Shiga, S. Nagano, Y. Li, H. Ishijima, H. Hachisu, M. Kumagai, and T. Ido, “Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr,” Appl. Phys. Express 5(2), 022701 (2012).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

F. Nakagawa, M. Imae, Y. Hanado, and M. Aida, “Development of multichannel dual-mixer time difference system to generate UTC(NICT),” IEEE Trans. Instrum. Meas. 54(2), 829–832 (2005).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

D. Akamatsu, H. Inaba, K. Hosaka, M. Yasuda, A. Onae, T. Suzuyama, M. Amemiya, and F.-L. Hong, “Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb,” Appl. Phys. Express 7(1), 012401 (2014).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

A. Yamaguchi, N. Shiga, S. Nagano, Y. Li, H. Ishijima, H. Hachisu, M. Kumagai, and T. Ido, “Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr,” Appl. Phys. Express 5(2), 022701 (2012).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

B. Miyahara, T. Kodama, and Y. Kuroishi, “Development of new hybrid geoid model for Japan, GSIGEO2011,” Bull. GSI 62, 11 (2014).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

M. S. Safronova, S. G. Porsev, U. I. Safronova, M. G. Kozlov, and C. W. Clark, “Blackbody-radiation shift in the Sr optical atomic clock,” Phys. Rev. A 87(1), 012509 (2013).

A. Yamaguchi, N. Shiga, S. Nagano, Y. Li, H. Ishijima, H. Hachisu, M. Kumagai, and T. Ido, “Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr,” Appl. Phys. Express 5(2), 022701 (2012).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

B. Miyahara, T. Kodama, and Y. Kuroishi, “Development of new hybrid geoid model for Japan, GSIGEO2011,” Bull. GSI 62, 11 (2014).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

J. Lodewyck, M. Zawada, L. Lorini, M. Gurov, and P. Lemonde, “Observation and cancellation of a perturbing dc stark shift in strontium optical lattice clocks,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 59(3), 411–415 (2012).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

A. Yamaguchi, N. Shiga, S. Nagano, Y. Li, H. Ishijima, H. Hachisu, M. Kumagai, and T. Ido, “Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr,” Appl. Phys. Express 5(2), 022701 (2012).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

T. Middelmann, S. Falke, C. Lisdat, and U. Sterr, “High accuracy correction of blackbody radiation shift in an optical lattice clock,” Phys. Rev. Lett. 109(26), 263004 (2012).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

J. Lodewyck, M. Zawada, L. Lorini, M. Gurov, and P. Lemonde, “Observation and cancellation of a perturbing dc stark shift in strontium optical lattice clocks,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 59(3), 411–415 (2012).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

J. Lodewyck, M. Zawada, L. Lorini, M. Gurov, and P. Lemonde, “Observation and cancellation of a perturbing dc stark shift in strontium optical lattice clocks,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 59(3), 411–415 (2012).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

Y. Huang, H. Guan, P. Liu, W. Bian, L. Ma, K. Liang, T. Li, and K. Gao, “Frequency comparison of two 40Ca+ optical clocks with an uncertainty at the 10−17 level,” Phys. Rev. Lett. 116(1), 013001 (2016).

A. A. Madej, P. Dubé, Z. Zhou, J. E. Bernard, and M. Gertsvolf, “88Sr+ 445-THz single-ion reference at the 10-17 level via control and cancellation of systematic uncertainties and its measurement against the SI second,” Phys. Rev. Lett. 109(20), 203002 (2012).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

T. Middelmann, S. Falke, C. Lisdat, and U. Sterr, “High accuracy correction of blackbody radiation shift in an optical lattice clock,” Phys. Rev. Lett. 109(26), 263004 (2012).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

B. Miyahara, T. Kodama, and Y. Kuroishi, “Development of new hybrid geoid model for Japan, GSIGEO2011,” Bull. GSI 62, 11 (2014).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

A. Yamaguchi, N. Shiga, S. Nagano, Y. Li, H. Ishijima, H. Hachisu, M. Kumagai, and T. Ido, “Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr,” Appl. Phys. Express 5(2), 022701 (2012).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

T. Ido, H. Hachisu, F. Nakagawa, and Y. Hanado, “Rapid evaluation of time scale using an optical clock,” J. Phys. Conf. Ser. 723, 012041 (2016).

F. Nakagawa, M. Imae, Y. Hanado, and M. Aida, “Development of multichannel dual-mixer time difference system to generate UTC(NICT),” IEEE Trans. Instrum. Meas. 54(2), 829–832 (2005).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10(-18) level,” Nature 506(7486), 71–75 (2014).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

D. Akamatsu, H. Inaba, K. Hosaka, M. Yasuda, A. Onae, T. Suzuyama, M. Amemiya, and F.-L. Hong, “Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb,” Appl. Phys. Express 7(1), 012401 (2014).

G. Panfilo, A. Harmegnies, and L. Tisserand, “A new prediction algorithm for the generation of International Atomic Time,” Metrologia 49(1), 49–56 (2012).

G. Panfilo and T. E. Parker, “A theoretical and experimental analysis of frequency transfer uncertainty, including frequency transfer into TAI,” Metrologia 47(5), 552–560 (2010).

G. Panfilo and P. Tavella, “Atomic clock prediction based on stochastic differential equations,” Metrologia 45(6), S108–S116 (2008).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

C. Y. Park, D. Yu, W. Lee, S. E. Park, E. B. Kim, S. K. Lee, J. W. Cho, T. H. Yoon, J. Mun, S. J. Park, T. Y. Kwon, and S. Lee, “Absolute frequency measurement of 1S0(F = 1/2)–3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS,” Metrologia 50(2), 119–128 (2013).

G. Panfilo and T. E. Parker, “A theoretical and experimental analysis of frequency transfer uncertainty, including frequency transfer into TAI,” Metrologia 47(5), 552–560 (2010).

D. Yu, M. Weiss, and T. E. Parker, “Uncertainty of a frequency comparison with distributed dead time and measurement interval offset,” Metrologia 44(1), 91–96 (2007).

H. Hachisu, G. Petit, and T. Ido, “Absolute frequency measurement with uncertainty below 1×10−15 using International Atomic Time,” Appl. Phys. B 123(1), 34 (2017).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

M. S. Safronova, S. G. Porsev, U. I. Safronova, M. G. Kozlov, and C. W. Clark, “Blackbody-radiation shift in the Sr optical atomic clock,” Phys. Rev. A 87(1), 012509 (2013).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

F. Riehle, “Towards a re-definition of the second based on optical atomic clocks,” C. R. Phys. 16(5), 506–515 (2015).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

M. S. Safronova, S. G. Porsev, U. I. Safronova, M. G. Kozlov, and C. W. Clark, “Blackbody-radiation shift in the Sr optical atomic clock,” Phys. Rev. A 87(1), 012509 (2013).

M. S. Safronova, S. G. Porsev, U. I. Safronova, M. G. Kozlov, and C. W. Clark, “Blackbody-radiation shift in the Sr optical atomic clock,” Phys. Rev. A 87(1), 012509 (2013).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

A. Yamaguchi, N. Shiga, S. Nagano, Y. Li, H. Ishijima, H. Hachisu, M. Kumagai, and T. Ido, “Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr,” Appl. Phys. Express 5(2), 022701 (2012).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

T. Middelmann, S. Falke, C. Lisdat, and U. Sterr, “High accuracy correction of blackbody radiation shift in an optical lattice clock,” Phys. Rev. Lett. 109(26), 263004 (2012).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

D. Akamatsu, H. Inaba, K. Hosaka, M. Yasuda, A. Onae, T. Suzuyama, M. Amemiya, and F.-L. Hong, “Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb,” Appl. Phys. Express 7(1), 012401 (2014).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

T. Tanabe, D. Akamatsu, T. Kobayashi, A. Takamizawa, S. Yanagimachi, T. Ikegami, T. Suzuyama, H. Inaba, S. Okubo, M. Yasuda, F.-L. Hong, A. Onae, and K. Hosaka, “Improved Frequency Measurement of the 1S0–3P0 Clock Transition in 87Sr Using a Cs Fountain Clock as a Transfer Oscillator,” J. Phys. Soc. Jpn. 84(11), 115002 (2015).

G. Panfilo and P. Tavella, “Atomic clock prediction based on stochastic differential equations,” Metrologia 45(6), S108–S116 (2008).

T. L. Nicholson, S. L. Campbell, R. B. Hutson, G. E. Marti, B. J. Bloom, R. L. McNally, W. Zhang, M. D. Barrett, M. S. Safronova, G. F. Strouse, W. L. Tew, and J. Ye, “Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty,” Nat. Commun. 6, 6896 (2015).

A. D. Ludlow, T. Zelevinsky, G. K. Campbell, S. Blatt, M. M. Boyd, M. H. G. de Miranda, M. J. Martin, J. W. Thomsen, S. M. Foreman, J. Ye, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, Y. Le Coq, Z. W. Barber, N. Poli, N. D. Lemke, K. M. Beck, and C. W. Oates, “Sr lattice clock at 1 × 10-16 fractional uncertainty by remote optical evaluation with a Ca clock,” Science 319(5871), 1805–1808 (2008).

G. Panfilo, A. Harmegnies, and L. Tisserand, “A new prediction algorithm for the generation of International Atomic Time,” Metrologia 49(1), 49–56 (2012).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

J. Lodewyck, S. Bilicki, E. Bookjans, J. Robyr, C. Shi, G. Vallet, R. Le Targat, D. Nicolodi, Y. Le Coq, J. Guena, M. Abgrall, P. Rosenbusch, and S. Bize, “Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock,” Metrologia 53(4), 1123–1130 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

Y. Lin, Q. Wang, Y. Li, F. Meng, B. Lin, E. Zang, Z. Sun, F. Fang, T. Li, and Z. Fang, “First evaluation and frequency measurement of the strontium optical lattice clock at NIM,” Chin. Phys. Lett. 32(9), 090601 (2015).

D. Yu, M. Weiss, and T. E. Parker, “Uncertainty of a frequency comparison with distributed dead time and measurement interval offset,” Metrologia 44(1), 91–96 (2007).

R. Le Targat, L. Lorini, Y. Le Coq, M. Zawada, J. Guéna, M. Abgrall, M. Gurov, P. Rosenbusch, D. G. Rovera, B. Nagórny, R. Gartman, P. G. Westergaard, M. E. Tobar, M. Lours, G. Santarelli, A. Clairon, S. Bize, P. Laurent, P. Lemonde, and J. Lodewyck, “Experimental realization of an optical second with strontium lattice clocks,” Nat. Commun. 4, 2109 (2013).

P. G. Westergaard, J. Lodewyck, L. Lorini, A. Lecallier, E. A. Burt, M. Zawada, J. Millo, and P. Lemonde, “Lattice-induced frequency shifts in Sr optical lattice clocks at the 10-17 level,” Phys. Rev. Lett. 106(21), 210801 (2011).

C. Grebing, A. Al-Masoudi, S. Dörscher, S. Häfner, V. Gerginov, S. Weyers, B. Lipphardt, F. Riehle, U. Sterr, and Ch. Lisdat, “Realization of a timescale with an accurate optical lattice clock,” Optica 3, 563 (2016).

St. Falke, N. Lemke, C. Grebing, B. Kipphardt, S. Weyers, V. Gerginov, N. Huntemann, Ch. Hagemann, A. Al-Masoudi, S. Hafner, S. Vogt, U. Sterr, and Ch. Lisdat, “A strontium lattice clock with 3×10−17 inaccuracy and its frequency,” New J. Phys. 16(7), 073023 (2014).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10(-18) level,” Nature 506(7486), 71–75 (2014).

St. Falke, H. Schnatz, J. S. R. V. Winfred, Th. Middelmann, St. Vogt, S. Weyers, B. Lipphardt, G. Grosche, F. Riehle, U. Sterr, and Ch. Lisdat, “The 87Sr optical frequency standard at PTB,” Metrologia 48(5), 399–407 (2011).

Y. Hiyama, A. Yamagiwa, T. Kawahara, M. Iwata, Y. Fukuzaki, Y. Shouji, Y. Sato, T. Yutsudo, T. Sasaki, H. Shigematsu, H. Yamao, T. Inukai, M. Ohtaki, K. Kokado, S. Kurihara, I. Kimura, T. Tsutsumi, T. Yahagi, Y. Furuya, I. Kageyama, S. Kawamoto, K. Yamaguchi, H. Tsuji, and S. Matsumura, “Revision of Survey Results of Control Points after the 2011 off the Pacific Coast of Tohoku Earthquake,” Bulletin of the GSI 59, 31 (2011).

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