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

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lenses is 150 mm, however the spacing is adjustable, allowing us to control the beam curvature and hence the location of the beam waist after it is focused by a 63.5 mm lens into the lower chamber glass cell. The power needed in the depopulation beam is very small, typically around a few nanowatts. 3.2.2 Far-Detuned Laser We use far-detuned laser beams to create optical dipole traps to confine atoms. A discussion of the theory used to estimate the depth of these traps is given in Sec. 2.5.1. There it was seen that in the limit of negligible saturation and a frequency detuning much larger than the fine structure splitting, the optical dipole potential is given by Udip(r) = 3πc2 2ω 3 0 Γ ∆ I(r). The laser used to create the optical dipole traps, the Verdi V10, is a commercially available turn-key system manufactured by Coherent, Inc. This laser outputs a single-mode (both longitudinally and transversely) with up to 10 W of power at 532 nm. The linewidth is specified to be < 5 MHz and was measured over 50 ms with a thermally stabilized reference etalon. The output beam diameter and divergence are specified to be 2.25 mm and < 0.5µrad, respectively. The beam is vertically polarized and nearly Gaussian (M 2 < 1.1). The pointing stability, power stability and RMS noise are specified as < 2µrad / ◦ C, ±1% and < 0.03%, respectively. These laser parameters are summarized in Table 3.1. 118
Output Power > 10 W Wavelength 532 nm Linewidth < 5 MHz Beam Diameter 2.25 ± 10% mrad M 2 < 1.1 Power Stability ±1% Pointing Stability < 2µrad Noise (RMS) < 0.03% Polarization Vertical, > 100 : 1 Table 3.1: Verdi V10 system specifications. The Verdi V10 outputs radiation at 532 nm which is far blue detuned from the 87 Rb D2 transition frequency. This means that Udip(r) is positive ev- erywhere and so a repulsive potential is formed. Our strategy to form 3D trap- ping potentials with repulsive barriers has been to use several “light sheets” to construct optical cups that hold the atoms against gravity. During the single- photon cooling process atoms are transferred from the magnetic trap into an optical cup. During the course of the experiments we used two main geome- tries for the construction of the cup: an “optical box” and “optical trough.” The process used to form these traps is very similar so I will only discuss the construction of the optical trough. The optical trough comprises four Gaussian sheets as shown in Fig. 3.20. The sheets were formed by asymmetrically focusing the beam with cylindrical lenses. Two sheets travel along the ˆx direction forming a “V”-shape. With the aid of gravity along the −ˆz direction these sheets confined the atoms along the ˆz and ˆy directions. Two more vertically elongated sheets traveling along 119
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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
Page 83 and 84: to vary linearly with position alon
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Page 91 and 92: 2.7.2 Saturation Absorption Spectro
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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
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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 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
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Page 163 and 164: μ μ μ
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
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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
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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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