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

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7.3.3 Optical Setup around the Spherical Octagon Around the science chamber octagon both laser system, the resonant laser system and the CO2 laser system are combined to create all necessary optical forces and potentials for the experiment, as well as providing the necessary beams for imaging purposes. In the near future an Nd:Yag laser will be added to provide the small optical dipole trap required for laser culling. The optical layout in the horizontal plane around the spherical octagon is shown in figure 7.38. The CO2 setup consists of a f = 5 in plano-convex lens, which focuses the CO2 beam at the location of the atoms. In order to be able to align the beam to the atoms, the lens is mounted on an x-y-z-translation stage. On the opposite side of the spherical octagon, a water-cooled beam dump collects the CO2 beam. The beams coming out of the MOT fibers are collimated by f = 50 mm lenses housed inside the fiber output coupler. Coming out of the fiber, the beam is linearly polarized. To change the polarization to circularly polarized light, MOT beam 1 passes through a quarter-wave plate before the spherical octagon. The beam is retro-reflected. In each pass the beam passes through a quarter-wave plate on the other side of the chamber to obtain the correct polarization for the retro-reflected beam. The second MOT beam is collimated the same way as MOT beam 1. How- ever, before passing through the mandatory quarter-wave plate, the beam is transmitted through a polarizing beam splitter cube. On the other side of the vacuum chamber two lenses (f = 125 mm and f = 400 mm) are mounted directly onto the viewport for imaging purposes. These lenses focus the MOT beam onto a reflective polarizer (Mox- tek, WGP00015). Before the polarizer, a quarter-wave plate changes the polarization to s-polarized light, which is reflected by the polarizer. The beam splitter cube is used to combine the absorption imaging beam with the MOT beam. After the quarter-wave plate the MOT and imaging beam polarizations have opposite handedness, and at the location of the reflective polarizer the imaging beam will be p-polarized and thus transmitted. This setup allows to image along a MOT beam axis. The two lenses mounted onto the viewport magnify the object by a 131
132 Figure 7.38: Optical layout around the spherical octagon. The horizontal MOT beams are shown in red, the CO2 beam in green. The blue lines show how images are formed along the two imaging axes. MOT ber 2 to Zeeman slower viewort Imaging ber 1 f=150mm beam dump CO2 nal focusing lens f=5 inches Alta CCD camera Imaging ber 2 MOT ber 1 Zeeman slower f=125mm f=400mm f=50mm Stingray CCD camera quarterwave plate mirror spherical lens polarizing beam splitter cube reective polarizer ber output coupler
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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
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5 2 P 3/2 5 2 S 1/2 384. 230 484 46
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distribution of the MOT master lase
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shifts. First a frequency shift of
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transition. However, the laser freq
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4.3.1.4 Upper MOT Horizontal Slave
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provides the beam for the upper MOT
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demon beam λ λ horizontal MOT bea
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scholar, Florian Schreck. It is wri
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Atoms are then optically pumped to
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ferred into the |F = 1,mF = 0〉 or
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5.2 Branching Ratios and Population
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effect of the reflected beam at zer
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y the repulsive trough beams, gaini
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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 and 120: Should contamination of the vacuum
Page 121 and 122: Figure 7.12: The assembled Zeeman s
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: CO2 laser 40 MHz AOM f=2 in f=2 in
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
Page 171 and 172: A typical MOT is density-limited at
Page 173 and 174: ubidium [113-115] and cesium[116].
Page 175 and 176: that most of the noise is due to th
Page 177 and 178: (a) (c) y . x z X=0.0mm Z=2.5mm 1)
Page 179 and 180: Figure 8.11: Different shapes of MO
Page 181 and 182: ZnSe lens f=5 in knife edge ZnSe wi
Page 183 and 184: shown in figure 8.13. By matching t
Page 185 and 186: Figure 8.15: Atom number and temper
Page 187 and 188: 275 Hz. Using these values the beam
Page 189 and 190: system. Maybe the easiest way to ac
Page 191 and 192: Appendix A Magic Wavelength of Hydr
Page 193 and 194: transitions for the excited state p
Page 195 and 196: Bibliography [1] J.J. Thomson. Cath
Page 197 and 198: [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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