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

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Figure 4.8: Width of atomic distribution as a function of expansion time for atoms cooled via the single-photon cooling process in the cross beam configuration. Black squares indicate raw data while the red line shows the best fit. See Sec. 2.8.1 for details on the function used to fit this data. allowing for far more quantitative analysis. The primary limitation in this iteration of the experiment was the short lifetime of the optical dipole trap (∼ 0.7 s). This lifetime set the timescale over which we could accumulate and hold atoms. After an unsuccessful attempt at increasing the lifetime of this attractive optical dipole trap we decided to use our Verdi V10 laser (see Sec. 3.2.2) to form a repulsive trap to transfer the atoms into. Use of this technique did result in a substantial increase in the lifetime of optically trapped atoms (∼ 3.7 s), allowing us to accumulate atom 144
numbers sufficiently large to quantify. This work serves as the topic of the next section. 4.3 “Optical Box” Configuration This section discusses the second major experimental iteration [95]. The major improvement made in this iteration was a change in the construction of the optical dipole trap. We stopped using the multi-mode ytterbium fiber lasers (1064 nm) to form an attractive potential and began using the Verdi V10 (523 nm) to form a repulsive potential to transfer the atoms into. The initial steps of loading atoms in to the magnetic trap was the same as that used in the previous section and described in Sec. 4.1. A thermal cloud of 87 Rb atoms is initially produced in a magneto- optical trap and then cooled in optical molasses. Subsequently atoms in the |F = 2〉 hyperfine ground state are loaded into a magnetic quadrupole trap with a radial field gradient of 75 G/cm. We trap approximately 1.7×10 8 atoms at a temperature of 90µK in a cloud with a 1/e radius of 550µm. After the magnetic trap is loaded, an optical dipole trap is positioned above it. The optical dipole trap originates the Verdi V10 which is split into three beams. Each beam passes through a dual-frequency acousto-optic modulator, and the first order deflections are tightly focused in one dimension to form parallel sheets. Each individual sheet has a 1/e 2 beam waist of 10µm × 200µm and a power of 0.7 W. The three pairs of sheets are crossed to form a repulsive “box-like” potential, with dimensions 100 µm × 100 µm × 130 µm 145
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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
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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
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Nor-Cal Products Inc. (AMV-1502-CF)
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and monitor the necessary vacuum le
Page 109 and 110: 3.1.3 Lower Chamber The lower chamb
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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
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Page 129 and 130: needed when forming a MOT or optica
Page 131 and 132: master laser is dithered at 20 kHz.
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Page 135 and 136: Output Power > 10 W Wavelength 532
Page 137 and 138: labeled 1, 2 and 3 in the Fig. 3.21
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Page 141 and 142: process. The two coils are arranged
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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: depopulation present and it indicat
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Page 165 and 166: the potential landscape due to the
Page 167 and 168: Figure 4.12: The number of atoms lo
Page 169 and 170: Figure 4.13: Incremental atom captu
Page 171 and 172: netic trap and transfer into the op
Page 173 and 174: temperature TB of atoms loaded into
Page 175 and 176: used to construct it into the remai
Page 177 and 178: 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
Page 183 and 184: detunings. The result of scattering
Page 185 and 186: are switched off causing non-optica
Page 187 and 188: 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
Page 193 and 194: atoms were removed from the magneti
Page 195 and 196: trappable |F = 1,mF = −1〉 state
Page 197 and 198: the short lived 2p state. Atoms whi
Page 199 and 200: 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
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adicals,” Phys. Rev. Lett. 94, 02
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