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Manipulation of ultracold Bose gases in a time-averaged orbiting potential
Cleary, P.W.
Publication date
2012
Link to publication
Citation for published version (APA):
Cleary, P. W. (2012). Manipulation of ultracold Bose gases in a time-averaged orbiting
potential.
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Contents
Contents v Foreword ix 1 Introduction 1 1.1 This Thesis . . . 2 1.2 Outline . . . 4 2 Experimental Set-up 5 2.1 Introduction . . . 5 2.2 Vacuum System . . . 6 2.3 Optics . . . 8 2.4 2D MOT . . . 11 2.5 3D MOT . . . 15 2.6 Magnetic trap . . . 182.6.1 Ioffe-Pritchard quadrupole trap . . . 18
2.6.2 Circuitry . . . 20
2.6.3 Additional coils for axial field control . . . 21
2.7 TOP trap . . . 23
2.8 RF evaporation . . . 24
2.9 Control . . . 25
3 Lasers and Imaging 29 3.1 Laser Systems . . . 30
3.1.1 Master Laser . . . 30
3.1.2 DFB laser . . . 31
3.1.3 Tapered amplifier . . . 33
3.1.4 Implementation and usages of stabilized lasers . . . 37
vi CONTENTS
3.2.1 Integration with MOT optics . . . 37
3.2.2 Resolution Tests . . . 39
3.2.3 Image blurring by the atoms . . . 42
3.2.4 Conclusions . . . 43
3.3 Analysis of Imaging Noise . . . 43
3.3.1 Method . . . 45
3.3.2 Camera . . . 46
3.3.3 Reducing the noise . . . 49
3.3.4 Conclusion . . . 52
4 Measurements with long-lived condensates 53 4.1 Introduction . . . 53
4.2 Trapping and condensing the |1, −1 state . . . . 54
4.2.1 Optical pumping scheme . . . 54
4.2.2 Magnetic transfer and evaporative cooling . . . 55
4.2.3 Imaging . . . 56
4.3 F = 1 BEC . . . 57
4.3.1 BEC characteristics and lifetime . . . 57
4.3.2 BEC of |1, −1 atoms in TOP trap . . . . 60
4.4 Vortex excitation and detection . . . 62
4.4.1 BEC and vortices . . . 62
4.4.2 Generation of vortices . . . 63
4.4.3 Excitation by rotation in a magnetic trap . . . 64
4.4.4 Vortex detection . . . 65
4.5 Experiments rotating the TOP . . . 66
4.5.1 Results with radial imaging . . . 67
4.5.2 Results with axial imaging . . . 67
4.5.3 Conclusions . . . 69
5 Manipulation using phase jumps of the TOP 71 5.1 Introduction . . . 71
5.2 Theory . . . 73
5.2.1 Time-averaged Ioffe-Pritchard potential . . . 73
5.2.2 Micromotion and macromotion . . . 75
5.2.3 Numerical analysis . . . 77 5.2.4 Phase jumps . . . 79 5.3 Experimental . . . 82 5.3.1 Apparatus . . . 82 5.3.2 Measurement procedure . . . 83 5.4 Analytic Model . . . 86
5.5 Results and discussion . . . 87
CONTENTS vii
A Quadrupole field with permanent magnets 93
Bibliography 97
Summary 105
Samenvatting 107
