ultra low cost single chamber bec apparatus with good optical access
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Ultra low cost single chamber BEC apparatus with good optical access
王如泉Laboratory for Solid State Quantum Information Science
The Institute of PhysicsThe 4th Young Researcher Symposium on Cold Atom Physics and Q
uantum information Dalian, China
August 5th, 2010
Atomic experiments at IOPBEC of 87RbPost 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
BEC of 87Rb BEC apparatus technical details
Single chamber design Home made DFB diode laser with simple frequency lock sc
heme All injection lock based laser system Second order RF modulation injection lock for repumping li
ght Unique dark MOT scheme Home developed real time timing control system based on
C and Labview BEC results Future improvements
Single chamber vs. double MOT BEC
Single chamber BEC Double MOT BEC
Single chamber BECJILA 103 pure BECStanford 104 pure BECIOP 105 pure BEC
Single chamber design vs. Double MOT design: advantages and disadvantagesSingle chamber Double MOT
Vacuum 1 chamber
1 pump
2 chambers
2 pumps
Laser cooling 6 laser beams 13 laser beams
Optical access4 free directions
2D optical lattice
3 free directions
1D optical lattice
No. of BEC atoms 1x105 (2 ~ 5)x105
Vacuum chamber details
DFB diode laser vs. external-DFB diode laser vs. external-cavity lasercavity laser
1. Great mechanical stability2. Large mode hopping free tuning range3. Very repeatable frequency tuning4. High precision temperature control (1mK)5. Less frequency cover6. Broader line width
DFB 二极管激光器 铷蒸汽室
锁相放大器
功率放大器
电流反馈
输入 参考
Master laser frequency lockMaster laser frequency lock
λ/2 λ/4
PID 控制器 输出
To experiment
Saturated spectroscopySaturated spectroscopy
780.2nm
6834.7MHz
F=3
F=2
F=1
F=0
F=2
F=1
Home made master DFB laser Home made master DFB laser
Precision temperature controller
Master laser
Magnetic field modulator
Precision current controller,Ramp generator and PID
To-3 package DFB diode with peltier cooler
Cooling laser system diagram
Master laser
Level 1 slave
80MHzAOM
Cooling laser
Repumping laser
200MHzAOM
Loading laser
200MHzAOM
80MHzAOM
3.4GHz RF Modulation
100MHzAOM
MOT Loading
Detection and optical pumping
CMOT & PGCDouble pass
To other slave lasersFor laser pumped
atomic magnetometer
Saturation spectroscopy(frequency lock
precision <1Mhz)
Repumping
Home made injection lock Home made injection lock laserslasers
Injection lock current controller
Injection lock temperature regulator
4 injection lock lasers
Master laser
Free running slave
Injected slave
频率
6.83GHz
Injection lock to the 2nd RF modulated harmonic side bandInjection lock to the 2nd RF modulated harmonic side band
dark mot: cooling -15MHz, loading -16.5normal mot: cooling -15MHz, loading -15MHzcooling power 20mW, diameter 11.4mm, total intensity 19.6mW/cm^2 loading power 80mW, diameter 22 mm, total intensity 21mW/cm^2
Dark MOT
QUIC trap :
3D magnetic field simulation Structure of the QUIC trap
0 2 4 6 8 10 12 14 160
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180轴 向 磁 场
B/G
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-10 -8 -6 -4 -2 0 2 4 6 8 100
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Axial magnetic field
XY plane equipotential lines Finite element thermal simulation Home-made QUIC trap coils
Typical QUIC trap performance
研究小组轴向曲率 Gs/cm^
2 径向梯度 Gs/cm
物理所 317 210
Hansch 260 225
York University 289 ?
北大 260 225
武汉物理所 (Ver 1) 167 189The University of Texas
at Austin 195 235
Timing control system
PC
PCI 6534
PCI 6713
RTSI
trigger
FPI 3
31 channel Digital output
8 channel Analog channel
……
……
Timing output datawith C++
System monitor with Labview
Output data fileAO, DO & Trigger
Powreful control system Bug fee operation
Imaging system
CMOT
MOT10ms
MOT
PGC Quadruple trap
Experimental results
原子数 /106
温度 /uK 密度 /cm3 PSD
MOT 5*107 80 2*1010 1*10-7
CMOT 4.5*107 60 2*1011 0.5*10-6
PGC 4*107 27 0.2*1011 1*10-6
Quadruple trap
3*107 160 2*1011 5*10-7
QUIC trap 3*107 130 1*1011 5*10-7
Cooling parameters
Vacuum trap life
1070KHz 1060KHz 1045KHz
Pure BEC has about 1*105 atomsFinal evaporation frequency: 1070, 1060, 1045 KHz.Time of flight 20 ms.
Anisotropic BEC expansion
Anisotropic free expansion of BEC time of expansion :1ms, 5ms, 9ms, 13ms, 17ms
Future improvements: LIAD
Light induced atom desorption (LIAD) can greatly increase atom number (5×105 pure BEC expected)
C. Klempt et al.
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
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
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。
磁场计工作原理
灵敏度极限
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)
HzT /105.0 15灵敏度和最好的 SQUID 竞争,但无需液氮或液氦。
50 pT Hz–1/2 灵敏度 , 由电池供电
米粒大的超小型磁场计
物理所原子磁场计结构图
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
磁场计输出信号 输出噪声能量谱
磁场测量灵敏度 50pT/√Hz
磁场计信号和灵敏度
87Rb-40K-6Li Bose Fermi MixtureMotivation•Extremely large Diopole-dipole interaction with hetero-nucleus molecules•System stability under cold collision
Ultra low collision cross section87Rb-87Rb |a|=100a0
7Li-7Li |a|=30a0
Experimental difficulties
/ 150elastic inelastic Run away condition
87Rb-40K-6Li mixture
Complicated laser system for STIRAPtwo lasers locked to a optical frequency comb
Successful group #1 DickermanEvaporation time =60s, small degenerate atom NoSuccessful group #2 R. Grimm100W dipole trap, very small degenerate atom No
Mini-trap, BEC of 7Li
Power dissipation <10W at 120ARadial field gradient 500G/cmAxial oscillation frequency 60HzTrap depth 80G
Thank you for your attention!