Single-Photon Atomic Cooling - Raizen Lab - The University of ...

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Table of Contents Acknowledgments v Abstract ix List of Tables xiii List of Figures xiv Chapter 1. Introduction 1 1.1 A Brief History of Laser Cooling . . . . . . . . . . . . . . . . 1 1.2 Laser Cooling as an Enabling Tool . . . . . . . . . . . . . . . . 4 1.3 Limitations of Laser Cooling . . . . . . . . . . . . . . . . . . . 5 1.4 Introduction to Single-Photon Cooling . . . . . . . . . . . . . 8 1.5 Single-Photon Cooling as a Maxwell’s Demon . . . . . . . . . . 16 1.6 A Note on Units . . . . . . . . . . . . . . . . . . . . . . . . . 19 Chapter 2. Operational Concepts 24 2.1 Rubidium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2 Fine and Hyperfine Structure . . . . . . . . . . . . . . . . . . . 26 2.2.1 Fine Structure . . . . . . . . . . . . . . . . . . . . . . . 26 2.2.2 Hyperfine Structure . . . . . . . . . . . . . . . . . . . . 29 2.3 The Zeeman Effect . . . . . . . . . . . . . . . . . . . . . . . . 34 2.4 Magnetic Trapping . . . . . . . . . . . . . . . . . . . . . . . . 40 2.5 Interaction of Light with Atoms . . . . . . . . . . . . . . . . . 45 2.5.1 The Optical Dipole Force . . . . . . . . . . . . . . . . . 45 2.5.2 Scattering Forces . . . . . . . . . . . . . . . . . . . . . . 49 2.5.2.1 Optical Bloch Equations . . . . . . . . . . . . . 50 2.5.2.2 Optical Molasses . . . . . . . . . . . . . . . . . 55 2.5.2.3 Sisyphus Cooling . . . . . . . . . . . . . . . . . 59 x
2.5.2.4 Magneto-Optical Trap . . . . . . . . . . . . . . 64 2.6 Branching Ratios . . . . . . . . . . . . . . . . . . . . . . . . . 68 2.7 Laser Frequency Control . . . . . . . . . . . . . . . . . . . . . 72 2.7.1 Doppler Broadening . . . . . . . . . . . . . . . . . . . . 72 2.7.2 Saturation Absorption Spectroscopy . . . . . . . . . . . 75 2.7.3 Laser Frequency Lock . . . . . . . . . . . . . . . . . . . 78 2.8 Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 2.8.1 Absorption Imaging . . . . . . . . . . . . . . . . . . . . 80 2.8.2 Fluorescence Imaging . . . . . . . . . . . . . . . . . . . 83 Chapter 3. Experimental Apparatus 85 3.1 Vacuum Chamber . . . . . . . . . . . . . . . . . . . . . . . . 85 3.1.1 Upper Chamber . . . . . . . . . . . . . . . . . . . . . . 86 3.1.2 Middle Chamber . . . . . . . . . . . . . . . . . . . . . 90 3.1.3 Lower Chamber . . . . . . . . . . . . . . . . . . . . . . 93 3.2 Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 3.2.1 Near-Resonance Lasers . . . . . . . . . . . . . . . . . . 96 3.2.1.1 MOT Master Laser . . . . . . . . . . . . . . . 98 3.2.1.2 Slave Lasers . . . . . . . . . . . . . . . . . . . 105 3.2.1.3 Upper MOT Horizontal Slave Laser . . . . . . 108 3.2.1.4 Upper MOT Diagonal Slave Laser . . . . . . . 110 3.2.1.5 Lower MOT Slave Laser . . . . . . . . . . . . . 112 3.2.1.6 Repump Master Laser . . . . . . . . . . . . . . 112 3.2.1.7 Depopulation Beam . . . . . . . . . . . . . . . 116 3.2.2 Far-Detuned Laser . . . . . . . . . . . . . . . . . . . . 118 3.3 Magnetic Trap . . . . . . . . . . . . . . . . . . . . . . . . . . 124 3.4 Imaging Systems . . . . . . . . . . . . . . . . . . . . . . . . . 127 3.4.1 Vertical Imaging . . . . . . . . . . . . . . . . . . . . . . 127 3.4.2 Horizontal Imaging . . . . . . . . . . . . . . . . . . . . 129 xi
Page 1 and 2: Copyright by Gabriel Noam Price 200
Page 3 and 4: Single-Photon Atomic Cooling by Gab
Page 5 and 6: Acknowledgments First, I would like
Page 7 and 8: Rubidium group when I first joined.
Page 9: Single-Photon Atomic Cooling Public
Page 13 and 14: List of Tables 2.1 87 Rb Physical P
Page 15 and 16: 3.1 Vacuum Chamber . . . . . . . .
Page 17 and 18: Chapter 1 Introduction This chapter
Page 19 and 20: the momentum kicks due to absorptio
Page 21 and 22: samples by allowing for very long i
Page 23 and 24: Figure 1.2: The energy level struct
Page 25 and 26: quency regime [19]. This then led t
Page 27 and 28: Figure 1.4: Depiction of a simple,
Page 29 and 30: demonstrates the cooling power of a
Page 31 and 32: a) b) c) external potential one-way
Page 33 and 34: worked on by Brillouin [27-29], ide
Page 35 and 36: the atomic ensemble. Not surprising
Page 37 and 38: are untrappable. The SI unit for en
Page 39 and 40: the atomic transition and is called
Page 41 and 42: 2.1 Rubidium Rubidium (Rb) is an al
Page 43 and 44: constant which is given by α = e2
Page 45 and 46: only one value of J is possible fro
Page 47 and 48: the latter of which only applies to
Page 49 and 50: Figure 2.1: 87 Rb D2 Transition Hyp
Page 51 and 52: Pluging Eq. 2.18 into this Hamilton
Page 53 and 54: Following the same logic leads to a
Page 55 and 56: gF = −1/2 using the approximate e
Page 57 and 58: mize their energy in high magnetic
Page 59 and 60: If we now consider the field from t
Page 61 and 62:
where P is in torr. The lifetime of
Page 63 and 64:
component of the dipole oscillation
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maxima. Our experiment makes extens
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atoms its wavefunction Ψ(t) is typ
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In this equation we let H = H0 + Hc
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The significance of Isat is that at
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Δ ω =ω−Δ ω =ω−Δ Δ
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where I/Isat ≪ 1 has been assumed
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λ λ Figure 2.9: The Sisyphus cool
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process repeats. If however, it dec
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σ σ σ Figure 2.10: Geomet
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to vary linearly with position alon
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0, ±1 and ∆mF = 0, ±1, allow ex
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this figure only the relevant hyper
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D2 transition in 87 Rb has a natura
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2.7.2 Saturation Absorption Spectro
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ground state depletion due to the p
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oadened background can be removed f
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where n is the number density of at
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where σ 2 c = σ 2 2 kBTt n + m .
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Chapter 3 Experimental Apparatus Th
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Figure 3.1: The vacuum chamber duri
Page 105 and 106:
Nor-Cal Products Inc. (AMV-1502-CF)
Page 107 and 108:
and monitor the necessary vacuum le
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3.1.3 Lower Chamber The lower chamb
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a) top ridge 1 cm b) metal jacket h
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to the appropriate frequency throug
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plexiglass cover piezo U stack grat
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λ Figure 3
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Voltage a b c d e f Frequency Figur
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eams. For example the MOT and optic
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λ Figure 3.12: The slave lasers
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λ λ λ
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λ λ λ λ
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needed when forming a MOT or optica
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master laser is dithered at 20 kHz.
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λ λ
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Output Power > 10 W Wavelength 532
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labeled 1, 2 and 3 in the Fig. 3.21
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λ λ λ λ
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process. The two coils are arranged
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19) connected in parallel. This arr
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3.4.2 Horizontal Imaging The horizo
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Chapter 4 Single-Photon Atomic Cool
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1 s, after which time ∼ 10 8 87 R
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(a) x z magnetically trapped atoms
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h x z magnetically trapped atoms y
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z y x magnetically trapped atoms cr
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Figure 4.5: The effective potential
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depopulation present and it indicat
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numbers sufficiently large to quant
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μ μ μ
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the potential landscape due to the
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Figure 4.12: The number of atoms lo
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Figure 4.13: Incremental atom captu
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netic trap and transfer into the op
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temperature TB of atoms loaded into
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used to construct it into the remai
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μ μ μ Figure 4.18: Side view of
Page 179 and 180:
Figure 4.20: Geometry of the optica
Page 181 and 182:
could potentially have undergone th
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detunings. The result of scattering
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are switched off causing non-optica
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Figure 4.25: Number (■) and tempe
Page 189 and 190:
traps. If we model the ensembles in
Page 191 and 192:
Figure 4.26: Radius of the atomic c
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atoms were removed from the magneti
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trappable |F = 1,mF = −1〉 state
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the short lived 2p state. Atoms whi
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Bibliography [1] R. Frisch, “Expe
Page 201 and 202:
[15] C. C. Bradley, C. A. Sackett,
Page 203 and 204:
[31] E.T. Jaynes, “Information th
Page 205 and 206:
[49] J. Ye, S. Swartz, P. Jungner,
Page 207 and 208:
[66] J.P. Gordon and A. Ashkin, “
Page 209 and 210:
[85] C.-S. Chuu, Direct Study of Qu
Page 211 and 212:
adicals,” Phys. Rev. Lett. 94, 02
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