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

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4.6 Transition Location . . . . . . . . . . . . . . . . . . . . . . . . 142 4.7 Fluorescence Images with and without Depopulation Beam . . 143 4.8 Temperature of Atoms Cooled in the Cross Beam Configuration 144 4.9 Optical Box Trap . . . . . . . . . . . . . . . . . . . . . . . . . 146 4.10 Calculated Potential due to the Optical Box Trap . . . . . . . 147 4.11 Total Potential in the |F = 2,mF = 2〉 and |F = 1,mF = 0〉 States. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 4.12 Number of Atoms loaded into Optical Box vs. Depopulation Beam Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 4.13 Incremental Atom Capture at a Fixed Translation Velocity . . 153 4.14 Captured Atom Number as a Function of Loading Time . . . 154 4.15 Atoms in Magnetic Trap vs. Gradient . . . . . . . . . . . . . . 158 4.16 Geometry of the “Optical Trough” . . . . . . . . . . . . . . . 159 4.17 “Optical Trough” Potential in the ˆy-ˆz Plane . . . . . . . . . . 160 4.18 “Optical Trough” Potential Side View . . . . . . . . . . . . . . 161 4.19 “Optical Trough” Potential Along ˆz and ˆx. . . . . . . . . . . . 162 4.20 “Optical Trough” and Depopulation Beam Geometry . . . . . 163 4.21 Atom Transfer vs. Depopulation Beam Intensity . . . . . . . . 164 4.22 Good/Bad Scattering Rates vs. Depopulation Beam Detuning 166 4.23 Total Potential for Atoms in the |F = 2,mF = 2〉 and |F = 1,mF = 0〉 State . . . . . . . . . . . . . . . . . . . . . . . . . 167 4.24 Absorption Image of Atoms in the Optical Trough . . . . . . . 170 4.25 Transfer Number and Vertical Temperature vs. Depopulation Beam Height . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 4.26 Magnetic Trap Radius vs. Temperature . . . . . . . . . . . . . 175 4.27 Measured Single-Photon Cooling Transfer Efficiencies . . . . . 176 4.28 Magnetically Trapped Atoms Remaining vs. Percentage of Current Ramp down Completed . . . . . . . . . . . . . . . . . . . 177 4.29 Atom Accumulation as Quadrupole Current is Ramped Down 178 4.30 Hydrogen Energy Structure Relevant to Single-Photon Atomic Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 xvi
Chapter 1 Introduction This chapter gives a brief introduction to the motivation and experimental methods developed and demonstrated in this dissertation. It begins with a brief discussion of the history of laser cooling. Next, the role laser cooling has played in advancing scientific knowledge is briefly presented. Finally, the method of single-photon atomic cooling, the topic of this dissertation, is presented in general terms and its advantages over established laser cooling techniques as well as its limitations are explored. 1.1 A Brief History of Laser Cooling Laser cooling of atomic vapors has a long and interesting history, however I will only attempt to highlight some key advancements in the field to place the development of single-photon cooling in the proper context. The first experiment in this field was carried out in 1933 by Frisch when he observed the deflection of an atomic beam by resonant light emitted from a sodium lamp [1]. In this experiment the deflection of the atomic beam was due to the scattering of a single resonant photon per atom on average. The important observation was that when a resonant photon is absorbed by an atom, in ad- 1
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 and 10: Single-Photon Atomic Cooling Public
Page 11 and 12: 2.5.2.4 Magneto-Optical Trap . . .
Page 13 and 14: List of Tables 2.1 87 Rb Physical P
Page 15: 3.1 Vacuum Chamber . . . . . . . .
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
Page 65 and 66: 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
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Nor-Cal Products Inc. (AMV-1502-CF)
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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
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Figure 4.20: Geometry of the optica
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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
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traps. If we model the ensembles in
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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,
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[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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