锶原子的激光冷却和囚禁
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摘要
基于激光冷却和囚禁的铯原子喷泉钟是目前准确度最高的时间频率基准,其频率不确定度已经进入10-16量级。而激光冷却中性原子或单离子光钟有潜力实现10-18的量级,比目前最好的喷泉钟高100倍以上。2006年第17届CCTF会议将锶原子的5s21S1-5s5p3P0作为时间频率的次级秒定义之一。在不远的将来,有可能代替铯原子频率标准成为更加先进的时间频率秒定义。
锶原子的冷却和囚禁是锶光钟研究中最基础也是最重要的一步。实验中,用锶原子单重态1S0-1P1的跃迁作为初级冷却,跃迁线宽约32 MHz,所对应激光为波长461nm的蓝光。利用原子的激光冷却和囚禁技术,用自旋翻转型塞曼减速器成功将大量锶原子从速度400 m／s以上冷却到速度50 m／s以下,并用磁光阱囚禁了锶原子,形成蓝MOT原子团。再加入二维准直、重泵浦激光后MOT中囚禁的原子数有10倍以上的增加。经过实验测量得到蓝MOT中的原子寿命为355 ms,原子数为108,温度为2-3mK。在461 nm激光冷却和囚禁的基础上,成功实现锶原子689 nm激光的红冷却,形成红MOT,并用吸收成像法拍照；初步估计原子从蓝MOT向红MOT的转移效率为20%；用荧光的飞行时间图像法初步测量红MOT原子团的温度为18μK。
Laser cooling and trapping Cs fountain clock with a frequency uncertainty of 10"15 is cuurently the most accurate primary frequency standard. Optical clock has the potential to reach an uncertainty of 10-18, more than 100 times better. In the 17th CCTF, the 5s2 1S1-5s5p 3P0 transition of Strontium atom was recommended to be one of the secondary definition of the SI base unit "second". Most possibly, the Cs fountain clock time and frequency standard will be re-defined with the optical clock in the near future.
This thesis summarizes our preliminary experiments about laser cooling and trapping of Strontium atoms, which are very important steps for the study of strontium optical lattice clock. The 1S0-1P1 transition which is used to pre-cool the strontium atoms has a natural linewidth of about 32 MHz, and the wavelenth is about 461 nm. The atoms beam is slowed down from 400 m/s to less than 50 m/s with a spin-flip Zeeman slower. The slow atoms are trapped in the blue Magneto-Optical Trap (blue MOT), and the atoms number in the trap is 10 times more with 2D collimation laser and repumping lasers. There are more than 108 atoms in the trap with a lifetime about 355 ms. The temperature measured with Time-Of-Fight (TOF) method is about 2-3 mK. About 20% atoms in the blue MOT are transferred to the red MOT with 689 nm laser. The atom cloud images are taken by a normal CCD with absorption imaging method and by an EMCCD with fluorescence imaging method. The TOF method is used to calculate the temperature of the atoms in the red Mot, the approximate temperature is about 18μK.
锶原子的冷却和囚禁是锶光钟研究中最基础也是最重要的一步。实验中,用锶原子单重态1S0-1P1的跃迁作为初级冷却,跃迁线宽约32 MHz,所对应激光为波长461nm的蓝光。利用原子的激光冷却和囚禁技术,用自旋翻转型塞曼减速器成功将大量锶原子从速度400 m／s以上冷却到速度50 m／s以下,并用磁光阱囚禁了锶原子,形成蓝MOT原子团。再加入二维准直、重泵浦激光后MOT中囚禁的原子数有10倍以上的增加。经过实验测量得到蓝MOT中的原子寿命为355 ms,原子数为108,温度为2-3mK。在461 nm激光冷却和囚禁的基础上,成功实现锶原子689 nm激光的红冷却,形成红MOT,并用吸收成像法拍照；初步估计原子从蓝MOT向红MOT的转移效率为20%；用荧光的飞行时间图像法初步测量红MOT原子团的温度为18μK。
Laser cooling and trapping Cs fountain clock with a frequency uncertainty of 10"15 is cuurently the most accurate primary frequency standard. Optical clock has the potential to reach an uncertainty of 10-18, more than 100 times better. In the 17th CCTF, the 5s2 1S1-5s5p 3P0 transition of Strontium atom was recommended to be one of the secondary definition of the SI base unit "second". Most possibly, the Cs fountain clock time and frequency standard will be re-defined with the optical clock in the near future.
This thesis summarizes our preliminary experiments about laser cooling and trapping of Strontium atoms, which are very important steps for the study of strontium optical lattice clock. The 1S0-1P1 transition which is used to pre-cool the strontium atoms has a natural linewidth of about 32 MHz, and the wavelenth is about 461 nm. The atoms beam is slowed down from 400 m/s to less than 50 m/s with a spin-flip Zeeman slower. The slow atoms are trapped in the blue Magneto-Optical Trap (blue MOT), and the atoms number in the trap is 10 times more with 2D collimation laser and repumping lasers. There are more than 108 atoms in the trap with a lifetime about 355 ms. The temperature measured with Time-Of-Fight (TOF) method is about 2-3 mK. About 20% atoms in the blue MOT are transferred to the red MOT with 689 nm laser. The atom cloud images are taken by a normal CCD with absorption imaging method and by an EMCCD with fluorescence imaging method. The TOF method is used to calculate the temperature of the atoms in the red Mot, the approximate temperature is about 18μK.
引文
[1].百度百科,“激光冷却”词条
[2]. S. A. Diddams, J. C. Bergquist, S. R. Jefferts, and C. W. Oates, Standardsof Time and Frequency at the Outset of the 21st Century, Science 306,1318 (2004).
[3]. S. Bize et al., Cold atom clocks and applications, Journal of Physics B, Atomic, Molecular and Optical Physics 38, S449 (2005).
[4].翟造成,张为群等,《原子钟基本原理与时频测量技术》,上海科学技术文献出版社,2009
[5]. I.I. Rabi, J. R. Zacharias, S. Millman, P. Kusch (1938). A New Method of Measuring Nuclear Magnetic Moment, Phys. Rev.,53:318.
[6]. N. F. Ramsey, A Molecular Beam Resonance Method with Separated Oscillating Fields, Phys. Rev.,1950,78,695
[7]. K. Shimoda, T. C. Wang and C. H. Townes, Phys. Rev.,1956,102,1308
[8]. L. Essen和J. V. L. Parry, Phil. Trans. R. Soc., London, Seres A,1957,250,45
[9]. J. L. Hall, Optical Frequency Measurement:40 Years of Technology Revolutions, IEEE Journ. Sel. Top. Quant. Electr.6,1136 (2000)
[10]. M. Arditi, J. L. Picgue, J. Phys. Lett.,1980,41,379-381
[11]. F. G. Major, G. Werth, Phys. Rev. Lett.,1973,30,1155-1158
[12]. T. Hansch, and A. Schawlow,1975, Cooling of gases by laser radiation, Opt. Commun.13,68.
[13]. D. Wineland, and H. Dehmelt,1975, Proposed 1014, laser fluorescence spectroscopy on TI1 mono-ion oscillatorⅢ, Bull. Am. Phys. Soc.20,637
[14]. A. Steane, C. Foot,1991, Europhys. Lett.,14,231
[15]. S. Chu, L. Hollberg, J.E. Bjorkholm, A. Cable, and A. Ashkin, in Laser Spectroscopy VII, T.W. Hansch and Y.R.Shen, eds., "Three Dimensional Viscous Confinement and cooling of Atoms by Resonance Radiation Pressure",1985, Springer-Verlag.
[16]. C. Monroe, W. Swann, H. Robinson, et al., Phys. Rev. Lett.,1990,65,1571
[17]. K. Gibble, S. Kasapi, S. Chu, Opt. Lett.,1992,17,526.
[18]. M. Kasevich, E. Riis, S. Chu, et al, Phys. Rev. Lett.,1989,63,612
[19]. A. Clairon, et. al. Quantum projection noise in an atomic fountain:A high stability Cs frequency standard, Proceedings of the 5th symposium on Frequency Standard and Metrology, London,1965.
[20]. R. Wynands and S. Weyers, Atomic fountain clocks, Metrologia 42(2005) S64-79
[21]. Longsheng Ma, et. al. "Optical Frequency Synthesis and Comparison with Uncertainty at the 10-19 Level", SCI. Vol.303,1843,2004
[22]. T.Rosenband, et. al. Frequency ratio of Al+ and Hg+ single-ion optical clock: Metrology at the 17th decimal place, Science,319,5871, pp:1808-1812 (2008),
[23]. H. Katori, M. Takamoto, et al., "Ultrastable optical clock with neutral atoms in an engineered light shift trap", Phys. Rev. Lett.91(17):173005(2003)
[24]. J. C. Bergquist, W. M. Itano, et al., "Recoilless optical absorption and Dopplersidebands of a single trapped ion", Phys. Rev. A 36(1):428(1987).
[25]. T. Ido and H. Katori, "Recoil-Free Spectroscopy of Neutral Sr Atoms in theLamb-Dicke Regime", Phys. Rev. Lett.91(5):053001(2003)
[26]. T. Ido and H. Katori, "Recoil-Free Spectroscopy of Neutral Sr Atoms in the Lamb-Dicke Regime", Phys. Rev. Lett.91(5):053001(2003)
[27]. D. J. Wineland, W. M. Itano, et al., "Laser-cooling limits and single-ion spectroscopy", Phys. Rev. A 36(5):2220(1987)
[28]. G. Wilpers, T. Binnewies, et al., "Optical Clock with Ultracold Neutral Atoms", Phys. Rev. Lett.89(23):230801(2002)
[29]. H. Katori, Spectoscopy of the Strontium atoms in the lamb-dicke confinement, Proceedings of the 6th Symposium on Frequency Standard and Metrology.
[30]. A. D. Ludlow, et. al. Sr lattice clock at 1×10-16 fractional uncertainty by remote optical evaluation with a Ca clock, Science 319,1805 (2008)
[31]. H. J. Metcalf and P. van der Straten, Laser Cooling and Trapping (Springer, ADDRESS,1999.
[32]. 王义遒,原子的激光冷却与陷俘,北京大学出版社,2007
[33]. C. N. Cohen-Tannoudji, Manipulating atoms with photons, Reviews Of Modern Physics 70,707 (1998).
[34]. P. D. Lett, W. D. Phillips, S. L. Rolston, C. E. Tanner, R. N. Watts, and C. I.Westbrook, Optical Molasses, Journal Of The Optical Society Of America B-Optical Physics 6,2084 (1989)
[35]. Y. Castin, H. Wallis, and J. Dalibard, Limit Of Doppler Cooling, Journal Of The Optical Society Of America B-Optical Physics 6,2046 (1989).
[36]. D. J. Wineland and W. M. Itano, Laser Cooling Of Atoms, Physical Review A 20,1521 (1979).
[37]. C. S. Adams and E. Riis, Laser cooling and trapping of neutral atoms, Progress In Quantum Electronics 21,1 (1997).
[38]. Reina Maruyama, Optical Trapping of Ytterbium Atoms, PHD. Theses.
[39]. W. Phillips, Nobel lecture, "Laser cooling and trapping of neutral atoms".
[40]. W. D. Phillips and H. Metcalf. Laser deceleration of an atomic-beam. Phys. Rev.Lett.,48(9):596-599,1982.
[41]. K. J. Gunter, Design and implementation of a Zeeman slower for 87Rb.
[42]. Steven Hoekstra, Atoms trap trace analysis of Calcium isotopes, PHD. Thesis.
[43]. Todd P. Meyrath, Electromagnet Design Basics for Cold Atom Experiments.
[44]. Chaneliere T., He L., Kaiser R., Wilkowski D., Loading, cooling and trapping of Strontium using intercombinaison line Submited to PRA (06/04/2007) [hal-00140366 version 1] (06/04/2007).
[45]. Andrew D. Ludlow, The Strontium Optical Lattice Clock:Optical Spectroscopy with Sub-Hertz Accuracy, PHD. Thesis.
[46]. M. Boyd, "High Precision Spectroscopy of Strontium in an Optical Lattice: Towards a New Standard for Frequency and Time", PHD thesis.
[47]. Xinye Xu, Thomas H. Loftus, John L. Hall, Alan Gallagher, and Jun Ye, "Cooling and trapping of atomic strontium".
[48]. Y. Li, T. Idol, T. Eichler, H. Katori,2004, "Narrow-line diode laser system for laser cooling of strontium atoms on the intercombination transition", Phys. B, 78,315.
[49]. T. E. Barrett, S. W. Dapore-Schwartz, M. D. Ray, and G. P. Lafyatis, Phys. Rev. Lett.67,3483 (1991).
[50]. I. Courtillot, A. Quessada, R. P. Kovacich, J-J. Zondy, A. Landragin, A. Clairon, and P. Lemonde OPTICS LETTERS/Vol.28, No.6/March 15,2003.
[51]. T. E. Barrett, S. W. Daporeschwartz, et al., "Slowing Atoms with (Sigma(-))-Polarized Light", Phys. Rev. Lett.67(25):3483-3487(1991).
[52]. Michael A. Joffe, Wolfgang Ketterle, Alex Martin, and David E. Pritchard Vol.10, No.12/December 1993/J. Opt. Soc. Am. B 2257.
[53]. I. Courtillot, A. Quessada, R. P. Kovacich, J-J. Zondy, A. Landragin, A. Clairon, and P. Lemonde Opt. Lett. Vol.28, No.6/March 15,2003.
[54]. P. A. Molenaar, P. van der Straten, and H. G. M. Heideman PHY. REV. A, 1997 VOL 55, No.1
[55]. C. J. Dedman etal REVIEW OF SCIENTIFIC INSTRUMENTS VOL.75, No.12 December 2004.
[56]. Toptica SHG110 Manuel.
[57]. 赵阳,硕士学位论文..
[58]. 李烨等,窄线宽689nm外腔半导体激光系统,成都2009时间频率年会.
[59]. 王强等,锶原子光钟二级冷却的前期实验,成都2009时间频率年会.
[60]. 林百科等,87Sr光钟系统中反亥姆霍兹线圈及驱动电路设计,成都2009时间频率年会.
[61]. Steven Chu et. al, Three-dimensional viscous confinement and cooling of atoms by resonance radiation pressurePhys. Rev.Lett.55 48,1985
[62]. Xinye xu, et. al. Dynamics in a two-level atom magneto-optical trap, Phys. Rev. A 66,011401,2002
[63]. Westbrook C I et al Localization of atoms in a three-dimensional standing wave, Phys.Rev. Lett.65 33,1990
[64]. Mitsunaga M et. al. Temperature diagnostics for cold sodium atoms by transient four-wave mixing Opt.Lett.23 840,1998
[65]. P. D. Lett et al, Observation of Atoms Laser Cooled below the Doppler Limit Phys. Rev. Lett.61 169,1985
[66]. T. M. Brzozowski, et. al. Time-of-flight measurement of the temperature of cold atoms for short trap-probe beam distances, J. Opt. B,4 62-66,2002
[67]. Wang Shao-kai, Wang Qiang, et. al. CHIN. PHYS. LETT. Vol 26, No.9, 093202
[68]. Wang Qiang, et. al. Magneto-Optical Trapping of 88Sr with 689nm Laser, ATF2010
[2]. S. A. Diddams, J. C. Bergquist, S. R. Jefferts, and C. W. Oates, Standardsof Time and Frequency at the Outset of the 21st Century, Science 306,1318 (2004).
[3]. S. Bize et al., Cold atom clocks and applications, Journal of Physics B, Atomic, Molecular and Optical Physics 38, S449 (2005).
[4].翟造成,张为群等,《原子钟基本原理与时频测量技术》,上海科学技术文献出版社,2009
[5]. I.I. Rabi, J. R. Zacharias, S. Millman, P. Kusch (1938). A New Method of Measuring Nuclear Magnetic Moment, Phys. Rev.,53:318.
[6]. N. F. Ramsey, A Molecular Beam Resonance Method with Separated Oscillating Fields, Phys. Rev.,1950,78,695
[7]. K. Shimoda, T. C. Wang and C. H. Townes, Phys. Rev.,1956,102,1308
[8]. L. Essen和J. V. L. Parry, Phil. Trans. R. Soc., London, Seres A,1957,250,45
[9]. J. L. Hall, Optical Frequency Measurement:40 Years of Technology Revolutions, IEEE Journ. Sel. Top. Quant. Electr.6,1136 (2000)
[10]. M. Arditi, J. L. Picgue, J. Phys. Lett.,1980,41,379-381
[11]. F. G. Major, G. Werth, Phys. Rev. Lett.,1973,30,1155-1158
[12]. T. Hansch, and A. Schawlow,1975, Cooling of gases by laser radiation, Opt. Commun.13,68.
[13]. D. Wineland, and H. Dehmelt,1975, Proposed 1014, laser fluorescence spectroscopy on TI1 mono-ion oscillatorⅢ, Bull. Am. Phys. Soc.20,637
[14]. A. Steane, C. Foot,1991, Europhys. Lett.,14,231
[15]. S. Chu, L. Hollberg, J.E. Bjorkholm, A. Cable, and A. Ashkin, in Laser Spectroscopy VII, T.W. Hansch and Y.R.Shen, eds., "Three Dimensional Viscous Confinement and cooling of Atoms by Resonance Radiation Pressure",1985, Springer-Verlag.
[16]. C. Monroe, W. Swann, H. Robinson, et al., Phys. Rev. Lett.,1990,65,1571
[17]. K. Gibble, S. Kasapi, S. Chu, Opt. Lett.,1992,17,526.
[18]. M. Kasevich, E. Riis, S. Chu, et al, Phys. Rev. Lett.,1989,63,612
[19]. A. Clairon, et. al. Quantum projection noise in an atomic fountain:A high stability Cs frequency standard, Proceedings of the 5th symposium on Frequency Standard and Metrology, London,1965.
[20]. R. Wynands and S. Weyers, Atomic fountain clocks, Metrologia 42(2005) S64-79
[21]. Longsheng Ma, et. al. "Optical Frequency Synthesis and Comparison with Uncertainty at the 10-19 Level", SCI. Vol.303,1843,2004
[22]. T.Rosenband, et. al. Frequency ratio of Al+ and Hg+ single-ion optical clock: Metrology at the 17th decimal place, Science,319,5871, pp:1808-1812 (2008),
[23]. H. Katori, M. Takamoto, et al., "Ultrastable optical clock with neutral atoms in an engineered light shift trap", Phys. Rev. Lett.91(17):173005(2003)
[24]. J. C. Bergquist, W. M. Itano, et al., "Recoilless optical absorption and Dopplersidebands of a single trapped ion", Phys. Rev. A 36(1):428(1987).
[25]. T. Ido and H. Katori, "Recoil-Free Spectroscopy of Neutral Sr Atoms in theLamb-Dicke Regime", Phys. Rev. Lett.91(5):053001(2003)
[26]. T. Ido and H. Katori, "Recoil-Free Spectroscopy of Neutral Sr Atoms in the Lamb-Dicke Regime", Phys. Rev. Lett.91(5):053001(2003)
[27]. D. J. Wineland, W. M. Itano, et al., "Laser-cooling limits and single-ion spectroscopy", Phys. Rev. A 36(5):2220(1987)
[28]. G. Wilpers, T. Binnewies, et al., "Optical Clock with Ultracold Neutral Atoms", Phys. Rev. Lett.89(23):230801(2002)
[29]. H. Katori, Spectoscopy of the Strontium atoms in the lamb-dicke confinement, Proceedings of the 6th Symposium on Frequency Standard and Metrology.
[30]. A. D. Ludlow, et. al. Sr lattice clock at 1×10-16 fractional uncertainty by remote optical evaluation with a Ca clock, Science 319,1805 (2008)
[31]. H. J. Metcalf and P. van der Straten, Laser Cooling and Trapping (Springer, ADDRESS,1999.
[32]. 王义遒,原子的激光冷却与陷俘,北京大学出版社,2007
[33]. C. N. Cohen-Tannoudji, Manipulating atoms with photons, Reviews Of Modern Physics 70,707 (1998).
[34]. P. D. Lett, W. D. Phillips, S. L. Rolston, C. E. Tanner, R. N. Watts, and C. I.Westbrook, Optical Molasses, Journal Of The Optical Society Of America B-Optical Physics 6,2084 (1989)
[35]. Y. Castin, H. Wallis, and J. Dalibard, Limit Of Doppler Cooling, Journal Of The Optical Society Of America B-Optical Physics 6,2046 (1989).
[36]. D. J. Wineland and W. M. Itano, Laser Cooling Of Atoms, Physical Review A 20,1521 (1979).
[37]. C. S. Adams and E. Riis, Laser cooling and trapping of neutral atoms, Progress In Quantum Electronics 21,1 (1997).
[38]. Reina Maruyama, Optical Trapping of Ytterbium Atoms, PHD. Theses.
[39]. W. Phillips, Nobel lecture, "Laser cooling and trapping of neutral atoms".
[40]. W. D. Phillips and H. Metcalf. Laser deceleration of an atomic-beam. Phys. Rev.Lett.,48(9):596-599,1982.
[41]. K. J. Gunter, Design and implementation of a Zeeman slower for 87Rb.
[42]. Steven Hoekstra, Atoms trap trace analysis of Calcium isotopes, PHD. Thesis.
[43]. Todd P. Meyrath, Electromagnet Design Basics for Cold Atom Experiments.
[44]. Chaneliere T., He L., Kaiser R., Wilkowski D., Loading, cooling and trapping of Strontium using intercombinaison line Submited to PRA (06/04/2007) [hal-00140366 version 1] (06/04/2007).
[45]. Andrew D. Ludlow, The Strontium Optical Lattice Clock:Optical Spectroscopy with Sub-Hertz Accuracy, PHD. Thesis.
[46]. M. Boyd, "High Precision Spectroscopy of Strontium in an Optical Lattice: Towards a New Standard for Frequency and Time", PHD thesis.
[47]. Xinye Xu, Thomas H. Loftus, John L. Hall, Alan Gallagher, and Jun Ye, "Cooling and trapping of atomic strontium".
[48]. Y. Li, T. Idol, T. Eichler, H. Katori,2004, "Narrow-line diode laser system for laser cooling of strontium atoms on the intercombination transition", Phys. B, 78,315.
[49]. T. E. Barrett, S. W. Dapore-Schwartz, M. D. Ray, and G. P. Lafyatis, Phys. Rev. Lett.67,3483 (1991).
[50]. I. Courtillot, A. Quessada, R. P. Kovacich, J-J. Zondy, A. Landragin, A. Clairon, and P. Lemonde OPTICS LETTERS/Vol.28, No.6/March 15,2003.
[51]. T. E. Barrett, S. W. Daporeschwartz, et al., "Slowing Atoms with (Sigma(-))-Polarized Light", Phys. Rev. Lett.67(25):3483-3487(1991).
[52]. Michael A. Joffe, Wolfgang Ketterle, Alex Martin, and David E. Pritchard Vol.10, No.12/December 1993/J. Opt. Soc. Am. B 2257.
[53]. I. Courtillot, A. Quessada, R. P. Kovacich, J-J. Zondy, A. Landragin, A. Clairon, and P. Lemonde Opt. Lett. Vol.28, No.6/March 15,2003.
[54]. P. A. Molenaar, P. van der Straten, and H. G. M. Heideman PHY. REV. A, 1997 VOL 55, No.1
[55]. C. J. Dedman etal REVIEW OF SCIENTIFIC INSTRUMENTS VOL.75, No.12 December 2004.
[56]. Toptica SHG110 Manuel.
[57]. 赵阳,硕士学位论文..
[58]. 李烨等,窄线宽689nm外腔半导体激光系统,成都2009时间频率年会.
[59]. 王强等,锶原子光钟二级冷却的前期实验,成都2009时间频率年会.
[60]. 林百科等,87Sr光钟系统中反亥姆霍兹线圈及驱动电路设计,成都2009时间频率年会.
[61]. Steven Chu et. al, Three-dimensional viscous confinement and cooling of atoms by resonance radiation pressurePhys. Rev.Lett.55 48,1985
[62]. Xinye xu, et. al. Dynamics in a two-level atom magneto-optical trap, Phys. Rev. A 66,011401,2002
[63]. Westbrook C I et al Localization of atoms in a three-dimensional standing wave, Phys.Rev. Lett.65 33,1990
[64]. Mitsunaga M et. al. Temperature diagnostics for cold sodium atoms by transient four-wave mixing Opt.Lett.23 840,1998
[65]. P. D. Lett et al, Observation of Atoms Laser Cooled below the Doppler Limit Phys. Rev. Lett.61 169,1985
[66]. T. M. Brzozowski, et. al. Time-of-flight measurement of the temperature of cold atoms for short trap-probe beam distances, J. Opt. B,4 62-66,2002
[67]. Wang Shao-kai, Wang Qiang, et. al. CHIN. PHYS. LETT. Vol 26, No.9, 093202
[68]. Wang Qiang, et. al. Magneto-Optical Trapping of 88Sr with 689nm Laser, ATF2010