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

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3.2.1 Near-Resonance Lasers Laser beams tuned near the resonance of the 87 Rb D2 transition are used for a variety of purposes in our experiment. This includes forming MOTs in conjunction with a magnetic field gradient. The frequency of these beams is typically about 15 MHz to the red of the |F = 2〉 → |F ′ = 3〉 transition. Because 87 Rb atoms occasionally decay into the |F = 1〉 manifold, where they are no longer resonant with the MOT beams, a repump beam is introduced into the system to place them back in the cooling cycle. The repump beam is resonant with the |F = 1〉 → |F ′ = 2〉 transition and serves to deplete atoms from the |F = 1〉 ground state. To cool atoms via optical molasses (Sec. 2.5.2.2) we use beams tuned 50 MHz to the red of the |F = 2〉 → |F ′ = 3〉 transition. To image and push atoms from the upper MOT to the lower MOT a beam resonant with the |F = 2〉 → |F ′ = 3〉 transition is used. To place atoms in a magnetically trappable state they are optically pumped by a laser resonant with the |F = 2〉 → |F ′ = 2〉 transition. Finally, to change the internal state of the atoms from |F = 2,mF = 2〉 to |F = 1,mF = 0〉 during the single-photon cooling process a depopulation beam is used. This beam is tuned 35 MHz to the red of the |F = 2〉 → |F ′ = 1〉 transition. A diagram of each of these beams in relation to the hyperfine structure of the 87 Rb D2 transition is given in Fig. 3.6. To generate the required frequencies and optical powers needed to per- form these tasks, a total of five diode lasers are used. Two of these diode lasers are master oscillators (called the MOT and repump master) and are locked 96
to the appropriate frequency through the saturation absorption spectroscopy laser frequency locking scheme discussed in Sec. 2.7.2 and Sec. 2.7.3. The remaining three diode lasers are injection locked by seeding them with light from the MOT master oscillator. The resultant near-resonance light is shifted in frequency with acousto-optic modulators to fine tune them to the precise frequency needed for each application. 5 2 P 3/2 5 2 S 1/2 384. 230 484 468 5(62) THz 780. 241 209 686(13) nm Absorption Imaging / Push Beam MOT Beam Molasses Beam 266.6500(90) MHz 156.9470(70) MHz 72.2180(40) MHz 6.834 682 610 904 290(90) GHz Figure 3.6: Near-resonance laser frequencies used in the experiment in relation to the hyperfine structure of the 87 Rb D2 transition. 97 Optical Pumping Beam Depopulation Beam Repump Beam F=3 F=2 F=1 F=0 F=2 F=1
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Copyright by Gabriel Noam Price 200
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Single-Photon Atomic Cooling by Gab
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Acknowledgments First, I would like
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Rubidium group when I first joined.
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Single-Photon Atomic Cooling Public
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2.5.2.4 Magneto-Optical Trap . . .
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List of Tables 2.1 87 Rb Physical P
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3.1 Vacuum Chamber . . . . . . . .
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Chapter 1 Introduction This chapter
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the momentum kicks due to absorptio
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samples by allowing for very long i
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Figure 1.2: The energy level struct
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quency regime [19]. This then led t
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Figure 1.4: Depiction of a simple,
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demonstrates the cooling power of a
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a) b) c) external potential one-way
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worked on by Brillouin [27-29], ide
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the atomic ensemble. Not surprising
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are untrappable. The SI unit for en
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the atomic transition and is called
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2.1 Rubidium Rubidium (Rb) is an al
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constant which is given by α = e2
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only one value of J is possible fro
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the latter of which only applies to
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Figure 2.1: 87 Rb D2 Transition Hyp
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Pluging Eq. 2.18 into this Hamilton
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Following the same logic leads to a
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gF = −1/2 using the approximate e
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mize their energy in high magnetic
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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
Page 67 and 68: atoms its wavefunction Ψ(t) is typ
Page 69 and 70: In this equation we let H = H0 + Hc
Page 71 and 72: The significance of Isat is that at
Page 73 and 74: Δ ω =ω−Δ ω =ω−Δ Δ
Page 75 and 76: where I/Isat ≪ 1 has been assumed
Page 77 and 78: λ λ Figure 2.9: The Sisyphus cool
Page 79 and 80: process repeats. If however, it dec
Page 81 and 82: σ σ σ Figure 2.10: Geomet
Page 83 and 84: to vary linearly with position alon
Page 85 and 86: 0, ±1 and ∆mF = 0, ±1, allow ex
Page 87 and 88: this figure only the relevant hyper
Page 89 and 90: D2 transition in 87 Rb has a natura
Page 91 and 92: 2.7.2 Saturation Absorption Spectro
Page 93 and 94: ground state depletion due to the p
Page 95 and 96: oadened background can be removed f
Page 97 and 98: where n is the number density of at
Page 99 and 100: where σ 2 c = σ 2 2 kBTt n + m .
Page 101 and 102: Chapter 3 Experimental Apparatus Th
Page 103 and 104: 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
Page 109 and 110: 3.1.3 Lower Chamber The lower chamb
Page 111: a) top ridge 1 cm b) metal jacket h
Page 115 and 116: plexiglass cover piezo U stack grat
Page 117 and 118: λ Figure 3
Page 119 and 120: Voltage a b c d e f Frequency Figur
Page 121 and 122: eams. For example the MOT and optic
Page 123 and 124: λ Figure 3.12: The slave lasers
Page 125 and 126: λ λ λ
Page 127 and 128: λ λ λ λ
Page 129 and 130: needed when forming a MOT or optica
Page 131 and 132: master laser is dithered at 20 kHz.
Page 133 and 134: λ λ
Page 135 and 136: Output Power > 10 W Wavelength 532
Page 137 and 138: labeled 1, 2 and 3 in the Fig. 3.21
Page 139 and 140: λ λ λ λ
Page 141 and 142: process. The two coils are arranged
Page 143 and 144: 19) connected in parallel. This arr
Page 145 and 146: 3.4.2 Horizontal Imaging The horizo
Page 147 and 148: Chapter 4 Single-Photon Atomic Cool
Page 149 and 150: 1 s, after which time ∼ 10 8 87 R
Page 151 and 152: (a) x z magnetically trapped atoms
Page 153 and 154: h x z magnetically trapped atoms y
Page 155 and 156: z y x magnetically trapped atoms cr
Page 157 and 158: Figure 4.5: The effective potential
Page 159 and 160: depopulation present and it indicat
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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
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[15] C. C. Bradley, C. A. Sackett,
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[31] E.T. Jaynes, “Information th
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[49] J. Ye, S. Swartz, P. Jungner,
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[66] J.P. Gordon and A. Ashkin, “
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[85] C.-S. Chuu, Direct Study of Qu
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adicals,” Phys. Rev. Lett. 94, 02
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