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Study on Correlation Length at Lambda Critical Point in an Ultracold Bose Gas

Study on Correlation Length at Lambda Critical Point in an Ultracold Bose Gas. — Joint Workshop on Bose Einstein Condensation and Ultracold Phenomena September 25-27 2013,Beijing,China. Xuzong Chen ( 陈徐宗 ) Institute of Quantum Electronics ( 量子电子学研究所） ,

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Study on Correlation Length at Lambda Critical Point in an Ultracold Bose Gas

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  1. Study on Correlation Length at Lambda Critical Point in an Ultracold Bose Gas —Joint Workshop on Bose Einstein Condensation and Ultracold Phenomena September 25-27 2013,Beijing,China Xuzong Chen (陈徐宗) Institute of Quantum Electronics (量子电子学研究所）, Peking University（北京大学）, China

  2. Welcome to visit Peking University

  3. Main Gate of Peking University

  4. Campus of Peking University

  5. Lake of Peking University

  6. School of Electronics Engineering and Computer Science, Peking University

  7. Institute of Quantum Electronics

  8. Laser Tech. Atomic clock MRI Quantum Information Cold Atom Electronic Technology Quantum Physics

  9. Research Quantum Optics and Quantum Information(Prof. Hong Guo) Ultra Laser (Prof. Zhigang Zhang) Cold atom and Precision Measurement (Prof. Xuzong Chen, Xiaoji Zhou) Magnetic Resonant Imaging ,(Asso. Prof. Weiming Wang) Optical Clock (Prof. Jingbiao Chen ) professors. 5, assoc. professors. 4, Assistant Prof. 3, staff 3, PhD students 34, master students 30

  10. Outline • Background • Measurement of phase transition and correlation between atoms in 1Doptical Lattice • Measurement of critical exponent at Lambda point in quantum gas • Future ultracold atom experiments in space

  11. Surface of sun H.K.Onnes, 1908,1919 Liquid Nitrogen Liquid 4He, superfluidity, superconductivity Bardeen ,1950, 1972 3He superfluidity, Doppler cooling,MOT D. Lee et al , 1970,1996 Sisyphus cooling S.Chu et al , 1980,1997 Subrecoil cooling, evaporative cooling, BEC Cornel, et al, 1995,2001 Cooling Roadmap and Phase Transition T(K)

  12. Quantum Phase Transition Cv/R T/Tc quantum liquid normal liquid quantum gas normal gas • Many body system • Exist critical temp: Tc • Superfluid while T<Tc (4) Lambda phase transition (5) H4 Boson, H3 Fermion, (6) Bose gas (Rb) , Fermi Gas (K)

  13. Evidence (1) of superfluid in quantum gas——vortex Bose Einstein Condensate helium-4 Science 292, 476 (2001)

  14. Evidence (2) of superfluid in quantum gas——quantum phase transition in optical lattice 1 D 2 D 3 D

  15. Phase Transition in 3D Optical Lattice 3 D superfluid Mott insulator

  16. superfluid Quantum Phase Transition M. Greiner et al. Nature 415, p38 (2002) Mott insulator

  17. Outline • Background • Measurement of phase transition and correlation between atoms in 1Doptical Lattice • Measurement of critical exponent at Lambda point in quantum gas • Future ultracold atom experiments in space

  18. Apparatus for Rb BEC Upper MOT Thank for Prof. Joerg Schmiedmayer Low MOT

  19. 1D Optical Lattice 1 D BEC Pancake BEC Bose-Hubbard model Superfluid phase U << J Mott insulating phase U >> J

  20. Primary phase transition between SF and MI Lattice Depth: 0, 5.6Er, 11.2Er, 16.9Er, 22.4Er, 28Er Fan Yang, Xiaoji Zhou, Juntao Li, Yuankai Chen, Lin Xia, and Xuzong Chen, Phys. Rev. A 78, 043611(2008)

  21. Correlation vs optical potential in 1D optical lattice Spatial correlation function d 1,2 3 2 1 1,3 x

  22. (2) Measurement on the Coherence of optical lattice (-1,0) (-1,0)

  23. Superradiation scattering in optical lattice Xu Xu, Xiaoji Zhou, and Xuzong Chen, Phys. Rev. A 79, 033605(2009) Thibault Vogt, Bo Lu, XinXing Liu, Xu Xu, Xiaoji Zhou, and Xuzong Chen, Phys. Rev. A 83, 053603 (2011)

  24. Superradiant scattering in 1D optical lattice pure BEC, V=0Er pure Optical Lattice (OL) , V=11Er MWA in Optical Lattice, V=11Er, MWA in Optical Lattice, V=34Er, superfluid Mott insulator

  25. Matter wave amplification VS delay time Power=4 mW pulse= 5 s Red Detuning = 1.3 GHz V= 11.44 Er 0 s 35 s 40 s 5 s 50 s 10 s 15 s 60 s 20 s 70 s 25 s 80 s 30 s

  26. Matter wave amplification VS delay time Power=4 mW pulse= 5 s Red Detuning = 1.3 GHz V= 11.44 Er 0 s 35 s 40 s 5 s 50 s 10 s 15 s 60 s 20 s 70 s 25 s 80 s 30 s

  27. 1,2 3 1 2 Bo Lu, Thibault Vogt, Xinxing Liu, Xu Xu, Xiaoji Zhou, and Xuzong Chen, Phys. Rev. A 83, 051608(R) (2011) Thibault Vogt, Bo Lu, XinXing Liu, Xu Xu, Xiaoji Zhou, and Xuzong Chen, Phys. Rev. A 83, 053603 (2011)

  28. Scattering light enhanced while matter wave grating in Δt = 2nπ/ωr Scattering light cancelled while matter wave grating in Δt = 2(n+1)π/ωr

  29. Vmax 1,1’ 2,2’ 3,3’ 3 1 1’ 2 2’ 3’ 1,0’ 2,1’ 3,2’ Δt Coherence of matter wave grating will be decreased while t increased, so that the visibility will be deceased

  30. Correlation decay in Mott insulator case Power=4 mW pulse= 5 s Red Detuning = 1.3 GHz V=36 Er 0 s 35 s 40 s 5 s 50 s 10 s 15 s 60 s 20 s 70 s 25 s 80 s 30 s Bo Lu, Thibault Vogt, Xinxing Liu, Xu Xu, Xiaoji Zhou, and Xuzong Chen, Phys. Rev. A 83, 051608(R) (2011)

  31. Outline • Background • Measurement of phase transition and correlation between atoms in 1Doptical Lattice • Measurement of critical exponent at Lambda point in quantum gas • Future ultracold atom experiments in space

  32. Critical behavior around phase transition point "for pioneering contributions to the theory of superconductors and super fluids" Alexei A. Abrikosov Vitaly L. Ginzburg Anthony J. Leggett The correlated length of gas around phase transition point is satisfied: "for his theory for critical phenomena in connection with phase transitions" critical temperature Critical factor Kenneth G. Wilson

  33. Critical exponents ——universal description on phase transition • the dimension of the system, • the range of the interaction, • the spin dimension. Correlation function correlated length

  34. Critical exponent ——phase transition in quantum gas The correlated length vs temperature correlated function M. Köhl, T. Donner, S. Ritter, T. Bourdel, A. Öttl, F. Brennecke, and T. Esslinger: Advances in Solid State Physics, 79-88 (2008) correlated length Critical exponent

  35. Measurement of the critical exponent at critical point in quantum gas Correlation function: Correlated length:

  36. Momentum filter——Talbot Effect Henry Fox Talbot（ 1836 ） Grating 2 Grating 1

  37. Matter Wave momentum filter By means of Talbot-Lau Effect Xiong, Wei; Zhou, Xiaoji; Yue, Xuguang; XuzongChen, NEW JOURNAL OF PHYSICS，Vol.15, 063025 (2013 )

  38. Momentum width compressed by momentum filter

  39. Correlated length: Signal to noise ratio:

  40. Critical behavior of Bose gas

  41. Bimode fitting approach Fixed momentum window fitting approach

  42. Outline • Background • Measurement of phase transition and correlation between atoms in 1Doptical Lattice • Measurement of critical exponent at Lambda point in quantum gas • Future ultracold atom experiments in space

  43. Surface of sun Liquid Nitrogen Liquid 4He, superfluidity, superconductivity 3He superfluidity, Doppler cooling,MOT Subrecoil cooling, evaporative cooling, BEC Cooling in Space T(K) Sisyphus cooling Cooling in space

  44. Technique challenge for cooling in space • On the ground Critical temperature for phase transition: ground： space： Operation time is needed：103 seconds

  45. Scheme for cooling in space Phase space distribution function Optical potential Total energy for the system Temperature for the system

  46. Procedure for cooling 28000 Rb atoms，with temperature of ~7 pK

  47. Procedure for cooling Ultracold Collision——Feshbach Resonance Motivation: Increase the collision rate and reduce cooling time 28000 Rb atoms，with temperature of ~7 pK

  48. Apparatus for Cs\Rb\K BEC Thank for Prof. Cheng Chin Science Chanmber

  49. Chinese Space station Core cabin launch in 2018, Science cabin launch in 2020

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