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Ultra low cost single chamber BEC apparatus with good optical access

Ultra low cost single chamber BEC apparatus with good optical access. 王如泉 Laboratory for Solid State Quantum Information Science The Institute of Physics The 4 th Young Researcher Symposium on Cold Atom Physics and Quantum information Dalian, China August 5 th , 2010.

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Ultra low cost single chamber BEC apparatus with good optical access

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  1. Ultra low cost single chamber BEC apparatus with good optical access 王如泉 Laboratory for Solid State Quantum Information Science The Institute of Physics The 4th Young Researcher Symposium on Cold Atom Physics and Quantum information Dalian, China August 5th, 2010

  2. Atomic experiments at IOP BEC of 87Rb Post doc 王晓锐 Graduate students 罗鑫宇 高奎意 Past student 曹强 Ultra sensitive optical pumped atomic magnetometer Graduate students 曹强 Past students 吴莎，伏吉庆，孔嘉 87Rb-40K-6Li Bose-Fermi mixture Post doc 张文卓 Graduate students 张峰 岳振华 刘鹏飞 Technician 赵渤 Quantum memory based on 87Rb in optical lattice (cooperation with 吴令安） Graduate students 裴莉亚 芦晓刚

  3. BEC of 87Rb • BEC apparatus technical details • Single chamber design • Home made DFB diode laser with simple frequency lock scheme • All injection lock based laser system • Second order RF modulation injection lock for repumping light • Unique dark MOT scheme • Home developed real time timing control system based on C and Labview • BEC results • Future improvements

  4. Single chamber vs. double MOT BEC Single chamber BEC JILA 103 pure BEC Stanford 104 pure BEC IOP 105 pure BEC Single chamber BEC Double MOT BEC

  5. Single chamber design vs. Double MOT design: advantages and disadvantages

  6. Vacuum chamber details

  7. DFB diode laser vs. external-cavity laser • Great mechanical stability • Large mode hopping free tuning range • Very repeatable frequency tuning • High precision temperature control (1mK) • Less frequency cover • Broader line width

  8. 铷蒸汽室 Master laser frequency lock PID控制器 锁相放大器 输出 输入 参考 功率放大器 λ/2 λ/4 电流反馈 DFB二极管激光器 To experiment

  9. Saturated spectroscopy F=3 F=2 F=1 F=0 780.2nm F=2 6834.7MHz F=1

  10. Home made master DFB laser Precision temperature controller Magnetic field modulator Master laser To-3 package DFB diode with peltier cooler Precision current controller, Ramp generator and PID

  11. Cooling laser system diagram 200MHz AOM Loading laser Saturation spectroscopy (frequency lock precision <1Mhz) MOT Loading Detection and optical pumping Master laser Level 1 slave Cooling laser 200MHz AOM 80MHz AOM 100MHz AOM Double pass CMOT & PGC Repumping laser 80MHz AOM Repumping 3.4GHz RF Modulation To other slave lasers For laser pumped atomic magnetometer

  12. Home made injection lock lasers Injection lock current controller 4 injection lock lasers Injection lock temperature regulator

  13. Injection lock to the 2nd RF modulated harmonic side band Master laser Free running slave 6.83GHz Injected slave 频率

  14. Dark MOT dark mot: cooling -15MHz, loading -16.5 normal mot: cooling -15MHz, loading -15MHz cooling power 20mW, diameter 11.4mm, total  intensity 19.6mW/cm^2  loading power 80mW, diameter 22 mm, total  intensity 21mW/cm^2 

  15. QUIC trap： 3D magnetic field simulation Axial magnetic field Structure of the QUIC trap XY plane equipotential lines Home-made QUIC trap coils Finite element thermal simulation

  16. Typical QUIC trap performance

  17. Timing control system 31 channel Digital output PC Timing output data with C++ …… PCI 6534 trigger Output data file AO, DO & Trigger RTSI FPI 3 System monitor with Labview PCI 6713 8 channel Analog channel …… Powreful control system Bug fee operation

  18. Imaging system

  19. Experimental results CMOT MOT10ms MOT Quadruple trap PGC

  20. Cooling parameters

  21. Vacuum trap life

  22. 1070KHz 1060KHz 1045KHz Pure BEC has about 1*105 atoms Final evaporation frequency: 1070, 1060, 1045 KHz. Time of flight 20 ms.

  23. Anisotropic BEC expansion Anisotropic free expansion of BEC time of expansion :1ms, 5ms, 9ms, 13ms, 17ms

  24. Future improvements: LIAD C. Klempt et al. Light induced atom desorption (LIAD) can greatly increase atom number (5×105 pure BEC expected)

  25. Future improvements: transfer and Feshbach coils, ultra high resolution in situ imaging • Additional transfer coils will be added to achieve full 3D optical access • High spatial imaging resolution <2μm • Feschbach resonance coils

  26. 超高灵敏度原子磁场计 应用前景 • 反潜 • 矿产勘探（重磁法） • 医学 (脑磁，心磁等) • 材料的内部劳损 • 航天器的磁场导航 • 陀螺仪

  27. 美国国家标准局，原子喷泉钟 斯坦福，原子重力计 耶鲁，原子陀螺仪 三种原子干涉仪的灵敏度受原子数的限制，并且结构非常复杂。 原子磁场计，原子数大很多数量级，结构简单，spin调控成本很低。

  28. 磁场计工作原理 灵敏度极限

  29. 灵敏度最高的原子磁场计，SERF磁场计 I. K. Kominis, T. W. Kornack, J. C. Allred & M. V. Romalis Nature 422, 596 - 599 (2003) 灵敏度和最好的SQUID竞争，但无需液氮或液氦。

  30. 米粒大的超小型磁场计 50 pT Hz–1/2灵敏度, 由电池供电

  31. 物理所原子磁场计结构图

  32. 原子磁场计实验装置 Helmholtz 线圈，用于抵消地磁场。 泵浦激光和探测激光器

  33. 磁场计信号和灵敏度 磁场计输出信号 输出噪声能量谱 磁场测量灵敏度50pT/√Hz

  34. 87Rb-40K-6Li Bose Fermi Mixture • Motivation • Extremely large Diopole-dipole interaction with hetero-nucleus molecules • System stability under cold collision

  35. Experimental difficulties Run away condition 87Rb-40K-6Li mixture Ultra low collision cross section 87Rb-87Rb |a|=100a0 7Li-7Li |a|=30a0 Successful group #1 Dickerman Evaporation time =60s, small degenerate atom No Successful group #2 R. Grimm 100W dipole trap, very small degenerate atom No Complicated laser system for STIRAP two lasers locked to a optical frequency comb

  36. Mini-trap, BEC of 7Li Power dissipation <10W at 120A Radial field gradient 500G/cm Axial oscillation frequency 60Hz Trap depth 80G

  37. Thank you for your attention!

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