Manipulation of Ultracold Bose Gases by Pulsed Standing

第六届全国冷原子物理和量子信息 青年学者学术讨论会—浙江金华 Manipulation of Ultracold Bose Gases by Pulsed Standing Wave 周小计 School of Electronic Engineering and Computer Science Peking University, Beijing 北京大学信息科学技术学院

Outline 1 Background 2 Interaction between a BEC and standing wave pulses 3 Observation of critical correlation 4 Discussion and Summary 2

Motivation of coherent amplification--- precise measurement l Coherent amplification of a weak signal l Coherent manipulate quantum states BEC in space ; Science 328, 1540(2010) Vacuum fluctuation: PRL 104, 195303(2010) BEC : Heisenberg uncertainty limit Nature 464 , 1165(2010); 1170(2010) 3

Typical cooperative scattering process A cigar-shaped BEC + GHz off-resonant pump laser + Time of flight (Science 285, 571(1999); Science 300, 475(2003)) 4

Matter wave Grating and Spatial distribution intensity; duration; detuning L. Deng, E. W. Hagley, Q. Cao, Xiaorui Wang, Xinyu Luo, R. Q Wang, M. G. L. Payne, Fan Yang, Xiaoji Zhou, X. Z. Chen, and Mingsheng Zhan, Phys. Rev. Lett. 105, 220404 (2010). 5

Cooperative scattering by traveling wave pulses for new parameters : Angle, Frequencies, Phase, Linewidth, Lattice l Bo Lu, Xiaoji Zhou*, T. Vogt, Zhen Fang, Xuzong Chen, Phys. Rev. A 83, 033620 (2011). l X. Liu, Xiaoji Zhou*, Wei Xiong, T. Vogt, and Xuzong Chen, Phys. Rev. A 83, 063402 (2011). l. T. Vogt, Bo Lu, X. Liu, Xu Xu, Xiaoji Zhou*, and Xuzong Chen, Phys. Rev. A 83 053603 (2011). l. Bo Lu, T. Vogt, X. Liu, Xu Xu, Xiaoji Zhou*, Xuzong Chen, Phys. Rev. A 83, 051608(R) (2011). l. Xiaoji Zhou* , F. Yang, X. G. Yue, T. Vogt, Xuzong Chen, Phys. Rev. A 81, 013615 (2010). l. Zhen Fang, Rui Guo, Xiaoji Zhou*, Xuzong Chen, Phys. Rev. A 82, 015601 (2010). l. L. Deng et al, Phys. Rev. Lett. 105, 220404 (2010). l. Xiaoji Zhou*, Phys. Rev. A 80, 023818 (2009)； l. Xiaoji Zhou* , Jiageng Fu, Xuzong Chen, Phys. Rev. A 80, 063608 (2009)； l. F. Yang, Xiaoji Zhou *, J Li, Y. K. Chen, L. Xia, X. Z. Chen, Phys. Rev. A 78, 043611 (2008)； 6

Several pumping frequencies Mechanism for Resonant Superradiant Scattering Fan Yang, Xiaoji Zhou *, J. Li, Y. Chen, Lin Xia, and X. Z. Chen, Phys. Rev. A 78, 043611 (2008). X. J. Zhou*, J. Fu, X. Z. Chen, Phys. Rev. A 80, 063608 (2009). 7

Relative phase of pump beams l Duration equals to periods, usual models do not predict. l The light relative initial phase is imprinted into two matter wave gratings. Xiaoji Zhou* , F. Yang, X. G. Yue, T. Vogt, Xuzong Chen, Phys. Rev. A 81, 013615 (2010). 8

Scattering Gain from an array of condensates Superradiant gain and direction of coherent radiant 850 nm nm 0 78 Xu Xu, Xiaoji Zhou *, and Xuzong Chen, Phys. Rev. A 79, 033605 (2009); 9

Competition between superradiance and wave amplification T. Vogt, Bo Lu, X. Liu, Xu Xu, Xiaoji Zhou*, and Xuzong Chen, Phys. Rev. A 83 053603 (2011) 10

Cooperative scattering measurement of coherence Effects of the interaction between atoms on band gap Bo Lu, T. Vogt, X. Liu, Xu Xu, Xiaoji Zhou*, Xuzong Chen, Phys. Rev. A 83, 051608(R) (2011). X. X. Liu, Xiaoji Zhou*, W. Zhang, T. Vogt, Bo Lu, X. G. Yue, X. Z Chen, Phys. Rev. A 83, 063604 (2011). 11

Outline 1 Background 2 Interaction between a BEC and standing wave pulses 3 Observation of critical correlation 4 Discussion and Summary 12

Manipulation of BEC by Standing Wave Pulses 13

Beyond Raman–Nath regime • High intensity and short pulse • the momentum representation

Projection theory in the Bloch band • • • Raman-Nath regime High intensity and short pulse Bragg regime low intensity and long pulse Tunneling regime 15

2. 1 Design Atomic interferometry momentum states Wei Xiong, Xuguang Yue, Zhongkai Wang, , Xiaoji Zhou*, X. Z Chen, Phys. Rev. A 84, 043616 (2011) 16

2. 2 Rapid nonadiabatic loading in an optical lattice adiabatic loading: 40 ms non-adiabatic loading: 40 us, loss 10 -3 X. X. Liu, Xiaoji Zhou*, W. Xiong, T. Vogt, and Xuzong Chen, Phys. Rev. A 83, 063402 (2011) 17

阱内脉冲 Pin=38 m. W, Pr=31 m. W Pin=38 m. W, Pr=9 m. W Pin=38 m. W, Pr=2. 3 m. W

阱外脉冲 Pin=38 m. W, Pr=31 m. W Pin=38 m. W, Pr=9 m. W Pin=38 m. W, Pr=2. 3 m. W

2. 4 Two standing wave pulses and interference

Temporal Talbot-Lau Interferometer(TLI) 34

Outline 1 Background 2 Interaction between a BEC and standing wave pulses 3 Observation of critical correlation 4 Discussion and Summary 36

Critical correlation Transition Textbooks tell us the correlation length diverges near the critical temperature Science 315, 1556, (2007): the interference of two released beams with a high-finesse optical cavity 38

Revelation of critical phase transition area under the broad peak; the total area in the bi-modal structure 39

The fraction of the filtered atoms as temperature Wei Xiong, Xiaoji Zhou*, Xuguang Yue, Xuzong Chen, Biao Wu, Hongwei Xiong*, submitted 40

The results based on the data fitting 1) Critical exponents: ν’ = 0. 70± 0. 08, ν =0. 70± 0. 11 universality XY Model: 0. 67 2) Amplitude ratio: field theory in 3 D: 0. 50; ǫ-expansion method: 0. 33 3) Critical temperature: interaction correction: 0. 05; finite-size correction: 0. 03 41

Outline 1 Background 2 Interaction between a BEC and standing wave pulses 3 Observation of critical correlation 4 Discussion and Summary 42

Summary l An efficient coherent control for the momentum states based on a sequence of standing wave pulses are given. l Effects of velocity of condensate and diffraction phases induced temporal asymmetry are discussed. l Observation of Critical Correlation Across Superfluid Lambda Transition in an Ultra-cold Bose Gas 45

Acknowledgement Collaborator Hongwei Xiong, Biao Wu Hui Zhai, Wei Zhang, Guangjiong Dong Lan Yin Helpful discusser Li You, Cheng Chin, Han Pu , Ying Wu , Jie Liu, Su Yi, Baolong Lu, Chaohong Lee, Vincent Liu, Guangjiong Dong, Jing Zhang, Tiancai Zhang, Shougang Zhang, Mingsheng Zhan, Ruquan Wang, Supeng Kou, Shuai Chen, Libing Fu, Junpeng Cao, Weidong Li, Yubo Zhang ……… 46