Experiments to Control Atom Number and Phase-Space Density in ...

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BGauss 0.4 0.3 0.2 0.1 0.1 zm Figure 7.11: Simulation of the Zeeman slower magnetic field profile. The black line shows the ideal magnetic field for decelerating atoms in the Zeeman slower. The green line shows the field of each of the eight individual Zeeman slower coils, the red line shows the field due to the MOT coils. Together the Zeeman slower coils and the MOT coils lead to the blue line. The origin is at the center of the MOT. temperatures of up to 200 ◦ C. Including the coating, the outer dimensions of the wire are 1.45 mm×1.45 mm. A layer of epoxy (Epoxy Technology, 360) is applied after each individual layer of the coil is wound to ensure mechanical stability and durability of the coils. Once the coil is finished, the epoxy is allowed to dry at room temperature over night. Subsequently the coils are baked at 100 ◦ C for one hour to cure the epoxy completely. The finished coils are then assembled onto a tube and mounted around the differential pumping tube. 600 400 200 200 The length of the Zeeman slower is 312 mm and the total distance from the start of the Zeeman slower to the center of the MOT is 414.7 mm. Each coil has 26 turns axially and between 5 and 19 layers radially. The inner radius of the coils is 15.5 mm. The Zeeman slower has a resistance of approximately 3.5 Ω, leading to a power dissipation of roughly 120 W. The individual parameters of each coil are listed in table 7.1. Before attaching the Zeeman slower to the vacuum chamber, the magnetic field 103
Figure 7.12: The assembled Zeeman slower. The total length of the slower is 312 mm. along the axis is measured using a Gaussmeter. The data (blue) is shown in figure 7.13 and compared to the expected field (grey) and the ideal magnetic field profile (black). Coil # Radial turns Resistance Current Power Outer diameter 1 19 0.87 Ω 5.8 A 29.3 W 85.9 mm 2 15 0.62 Ω 5.8 A 20.9 W 74.4 mm 3 13 0.51 Ω 5.8 A 17.2 W 68.6 mm 4 12 0.46 Ω 5.8 A 15.4 W 65.7 mm 5 11 0.41 Ω 5.8 A 13.7 W 62.8 mm 6 10 0.36 Ω 5.8 A 12.1 W 59.9 mm 7 8 0.26 Ω 5.8 A 9.1 W 54.1 mm 8 5 0.15 Ω 4.3 A 2.8 W 45.5 mm Table 7.1: Properties of the Zeeman slower coils Using the combination of the MOT coils and the Zeeman slower coils to produce the Zeeman slower field profile has some advantages over other designs. In this setup the Zeeman slower finishes deceleration of the atoms right at the location of the MOT. If the Zeeman slower ended before the trapping volume of the MOT, the decelerated and thus slow atoms would still have to travel some distance before being captured by the MOT beams. Due to the transverse velocity of the atoms, the density of atoms at the center of the MOT would therefore be reduced, potentially leading to smaller trapped 104
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Copyright by Kirsten Viering 2012
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Experiments to Control Atom Number
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Acknowledgments First of all, I wou
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Experiments to Control Atom Number
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Table of Contents Acknowledgments v
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Chapter 7. Lithium Apparatus 92 7.1
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List of Tables 2.1 Physical propert
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4.1 Vacuum chamber . . . . . . . .
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7.39 Future vertical axis optics .
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The development of techniques to la
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Ptorr 10 5 10 6 10 7 10 8 10 9 260
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Property Symbol Value Reference Ato
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2.3.2 Hyperfine Structure So far th
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The Wigner-Eckhart theorem can be u
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The total magnetic moment of an ato
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interaction. The shift in the energ
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(a) (b) scattering length a 0 Energ
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a laser field with frequency ω. Th
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Here ω0 is the resonance frequency
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Optical molasses do not provide a s
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J=1 J=0 -1 Δ σ + σ - σ - 0 +1 -
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phase-space density is defined as
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which maintains a constant η = U/k
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2.12.1 Saturated Absorption Spectro
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Figure 2.22: Saturation absorption
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Signal 0 Signal (a) (b) Signal Freq
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(a) (b) (c) (d) Figure 2.24: Absorp
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y more complex energy level structu
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ight side of the box. An irreversib
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time (a) (b) (c) Figure 3.3: Single
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them to move from B to A, but close
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Figure 4.1: Vacuum chamber. Photogr
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( ( Figure 4.3: Helicoflex seal. (a
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88 mm 4.2.3 Auxiliary Coils 62 mm Q
Page 69 and 70: 5 2 P 3/2 5 2 S 1/2 384. 230 484 46
Page 71 and 72: distribution of the MOT master lase
Page 73 and 74: shifts. First a frequency shift of
Page 75 and 76: transition. However, the laser freq
Page 77 and 78: 4.3.1.4 Upper MOT Horizontal Slave
Page 79 and 80: provides the beam for the upper MOT
Page 81 and 82: demon beam λ λ horizontal MOT bea
Page 83 and 84: scholar, Florian Schreck. It is wri
Page 85 and 86: Atoms are then optically pumped to
Page 87 and 88: ferred into the |F = 1,mF = 0〉 or
Page 89 and 90: 5.2 Branching Ratios and Population
Page 91 and 92: effect of the reflected beam at zer
Page 93 and 94: y the repulsive trough beams, gaini
Page 95 and 96: Figure 5.9: Atom number as a functi
Page 97 and 98: Figure 5.10: Radius of the magnetic
Page 99 and 100: on the collision rate of atoms insi
Page 101 and 102: ferred via the single-photon coolin
Page 103 and 104: By comparison an atomic Fock state
Page 105 and 106: of atoms in the two hyperfine groun
Page 107 and 108: difference in the lifetimes is dete
Page 109 and 110: Chapter 7 Lithium Apparatus Creatin
Page 111 and 112: angle valve rotary feedthrough ion
Page 113 and 114: an ion gauge controller (Granville
Page 115 and 116: viewports (MDC, 450002) are attache
Page 117 and 118: not trapped by the MOT impinge on t
Page 119: Should contamination of the vacuum
Page 123 and 124: 7.2.2 MOT Coils A second set of coi
Page 125 and 126: BGauss 250 200 150 100 50 30 20 10
Page 127 and 128: are required to create the high mag
Page 129 and 130: The coils are then checked for shor
Page 131 and 132: + B A Figure 7.23: Feshbach coil H-
Page 133 and 134: ensure that no particulates build u
Page 135 and 136: 118 Figure 7.26: Optical layout of
Page 137 and 138: The error signal shows three lines,
Page 139 and 140: into the CO2 laser. The optical lay
Page 141 and 142: Thorlabs PDA10A Coupler ZDC-10-1 to
Page 143 and 144: Imaging ber Imaging ber from Imagin
Page 145 and 146: Table 7.4 summarizes the beam power
Page 147 and 148: CO2 laser 40 MHz AOM f=2 in f=2 in
Page 149 and 150: 132 Figure 7.38: Optical layout aro
Page 151 and 152: Feshbach coil objective lenses atom
Page 153 and 154: MOT beams are no longer traveling a
Page 155 and 156: The second card (NI6733) offers eig
Page 157 and 158: Averaging over the magnetic subleve
Page 159 and 160: 2 2 P 3/2 D 2=670.977nm 2 2 S 1/2 m
Page 161 and 162: The right hand side of equation 7.1
Page 163 and 164: = E0 1 −n2 √2 exp σ0 ± iE0
Page 165 and 166: esidual potentials besides gravitat
Page 167 and 168: Figure 8.1: MOT loading. Typical lo
Page 169 and 170: A linear ramp typically changes the
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A typical MOT is density-limited at
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ubidium [113-115] and cesium[116].
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that most of the noise is due to th
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(a) (c) y . x z X=0.0mm Z=2.5mm 1)
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Figure 8.11: Different shapes of MO
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ZnSe lens f=5 in knife edge ZnSe wi
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shown in figure 8.13. By matching t
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Figure 8.15: Atom number and temper
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275 Hz. Using these values the beam
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system. Maybe the easiest way to ac
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Appendix A Magic Wavelength of Hydr
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transitions for the excited state p
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Bibliography [1] J.J. Thomson. Cath
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[22] C.J. Foot. Atomic Physics. Oxf
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[46] E.D. Black. An introduction to
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[67] J.L. Hanssen. Controlling Atom
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[88] D.S. Naik, C.G. Peterson, A.G.
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[110] J.W. Goodman. Introduction to
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[132] C. Degenhardt, H. Stoehr, U.
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