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

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3.2.1.1 MOT Master Laser The MOT master laser is based around a simple, inexpensive single- mode laser diode. The diode used in the experiment was purchased from Intelite Inc. (model: MLD-780-100S5P). This model operates nominally at a wavelength of 780 nm and output power of 100 mW with an injection current of 120mA. The diode is made to lase at a chosen frequency and with a narrow bandwidth by placing it in a Littrow configured, grating-stabilized cavity [91, 92]. The cavity is shown in Fig. 3.7 and is formed from the reflective back facet of the laser diode and a grating. The diode is positioned in the cavity by first placing it in a collimation tube (Thorlabs, LT230P-B) which bundles its output into a low divergence beam. This is then inserted into a bronze holder which slides into a bronze mounting block, directing the optical radiation towards the grating. The grating (Edmund Scientific) is formed from a 500˚A thick gold coating with 1200 grooves/mm etched into it. The grating face measures 12.5 × 12.5 mm. In the Littrow configuration the grating serves as both a cavity end mirror and an output coupler. The 1 st order reflection off of the grating is directed back into the laser diode, while the 0 th order reflection is used as the output beam. For the 1 st order beam to reflect back into the laser diode, the angle of incidence of the incoming beam with respect to the grating surface must satisfy the Littrow condition mλ = 2dsin(α), (3.1) 98
plexiglass cover piezo U stack grating output window diode in collimating tube and holder Figure 3.7: The MOT master laser is a simple laser diode placed in a Littrow configured cavity. The laser cavity is placed within a Plexiglass cover to help isolate it thermally from the environment. where m is the order of the reflection, λ is the wavelength of light, d is the groove spacing, and α is the angle of incidence. For a first-order reflection of a beam at 780 nm off of a grating with a line spacing of d = (1200grooves/mm) −1 = 0.833µm, the incident angle must be 27.9 ◦ for the beam to return to the laser diode. The lasing wavelength can be tuned in this configuration by slightly adjusting the angle of the grating which in turn slightly changes the cavity length and therefore the supported mode frequency. For stable operation both the temperature and laser diode injection current must be regulated as they both affect the lasing frequency. The temperature of the laser diode is monitored with a 50kΩ glass-bead thermistor 99
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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
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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)
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Page 109 and 110: 3.1.3 Lower Chamber The lower chamb
Page 111 and 112: a) top ridge 1 cm b) metal jacket h
Page 113: to the appropriate frequency throug
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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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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