Experiments with Supersonic Beams as a Source of Cold Atoms

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Figure 5.23: A schematic of the original hydrogen laser. A tunable extended cavity diode laser (ECDL) produces single-mode light at 972 nm which is verified by a Fabry-Perot cavity and wavemeter. The light from the diode is amplified in a tapered amplifier (TA) and injected into a doubling cavity. After doubling the light is at 486 nm, where Tellurium spectroscopy is performed to lock the laser. The blue light is injected into another doubling cavity, which produces 243nm light. Figure Courtesy Travis Bannerman. are verified by a wavemeter and Fabry-Perot cavity respectively. Since the output of the diode laser (Eagleyard Photonics RWE-0980-08020-1500-SOT02) is limited to about 70 mW and the doubling processes are nonlinear, where the efficiency of the doubling goes as the square of the power, it is necessary to amplify the laser before injecting it into the first doubling cavity. This is done using a tapered amplifier (TA). The TA (Toptica Photonics BoosTA-L-980) takes approximately 35 mW of 972 nm light (after isolation, diagnostics, spatial filtering, and mode-matching), and amplifies it to approximately 1 W, which results in approximately 900 mW of power which can be injected into the first doubling cavity after isolation and mode-matching. The doubling cavity is a bow-tie cavity locked to the frequency of the diode laser. A nonlinear lithium triborate (LBO) crystal doubles the frequency of the light to 486 nm, which is coupled out of the cavity by a dichroic mirror. The doubling cavity (Coherent MBD-200) produces around 100 mW of light at 486 nm. This light 153
Figure 5.24: A schematic of the tellurium saturated absorption spectroscopy setup. The frequency of the pump beam is offset by double passing through a 57 MHz AOM that compensates for the frequency difference between the line in tellurium and the 1/4 harmonic of the hydrogen line. Figure Courtesy Travis Bannerman. is mode-matched to a second doubling cavity, which is identical to the first except that it uses a beta barium borate (BBO) crystal as the nonlinear medium instead of LBO. The BBO crystal is used because of its optical properties in the UV. The second doubling cavity produces approxiately 2 mW of light at 243 nm. Between the first and second doublers, approximately 10 mW of 486 nm light is picked out of the beam and used in a saturated absorption spectroscopy setup to lock the diode laser frequency. More detail on saturated absorption spectroscopy can be found in [111]. Molecular tellurium is used as a frequency reference for the diode since the lines around 486nm have been mapped to better than 1MHz [112–114], and the i2 line has been found to be approximately 57MHz above the 1/4 harmonic of the 1S − 2S transition [115]. This frequency difference can be compensated for by double passing the pump beam of the saturated absorption setup through an acousto-optic modulator (AOM), as shown in figure 5.24. The spectroscopy signal is fed back to the piezo on the diffraction grating, locking the laser frequency. More detail on the laser setup can be found in [116]. 154
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Copyright by Adam Alexander Libson
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General Methods of Controlling Atom
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Acknowledgments First and foremost,
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to problems, and I frequently went
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General Methods of Controlling Atom
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Table of Contents Acknowledgments v
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Chapter 5. Towards Trapping and Coo
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List of Figures 2.1 Comparison of e
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5.12 Faraday Rotation Signal During
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producing a cold sample. Alternativ
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place inside a dilution refrigerato
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atoms or molecules are slowed using
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2.1 Thermodynamics of Ideal Gases F
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Since there will be no heat exchang
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Using equation 2.17 to modify equat
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Normalized Effusive Beam Flux Norma
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general method for producing cold a
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The gas throughput of the nozzle ca
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Chapter 3 Slowing Supersonic Beams
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3.1 Using Helium for Atom Optics Ex
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Figure 3.1: Calculated elastic scat
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that they can be prepared ex-situ a
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successful. Any water that remains
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Skimmer 300 l/s Turbo Pump Even-Lav
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Figure 3.5: A CAD image of the dete
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from tubular aluminum welded togeth
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Figure 3.7: A CAD image of the roto
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Figure 3.10: A CAD image of large c
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Figure 3.11: This plot shows the am
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approximations are made in this cal
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3.3.3 Detection An SRS [61] residua
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TTL pulse to the data acquisition c
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A comparison of the time-of-flight
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eceding crystal. Each curve is the
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calculated slow beam velocity is qu
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the RGA does have an effect on the
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Chapter 4 The Atomic and Molecular
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field. In the L − S coupling regi
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3 P2 E Figure 4.2: This graph gives
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For intermediate fields, the full p
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Figure 4.4: This figure illustrates
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The same effect is also responsible
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(a) (b) (c) Time Figure 4.5: A pict
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which the particles enter). The oth
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the coil can instead be switched be
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the magnitude of the field some dis
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nozzle front surface aluminum catho
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Figure 4.9: A CAD overview of the s
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258V 1MΩ 5V 1mF DC/DC Converter TT
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Figure 4.12: An oscilloscope trace
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(a) (b) Figure 4.14: A CAD image of
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-HV PS 4 M MCP Anode 10 M 1 M Trans
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Signal [V] 2.5 2.0 1.5 1.0 0.5 refe
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Figure 4.20: An exploded view of th
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(a) (b) (c) (e) Figure 4.21: A pict
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258V 1MΩ TTL 2.2mF 50Ω TTL 5V 5V
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closed. With the new thyristor gate
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HeNe M2 M1 BB /2 L BB PC coil PC PD
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Table 4.1: Peak magnetic fields mea
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Page 121 and 122: ameters. The coilgun chamber consis
Page 123 and 124: Table 4.2: Final velocities (vf), s
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Page 135 and 136: Energy meV 0.05 0.00 0.05 0.0 0.2 0
Page 137 and 138: 10 mm 2.0 T 1.8 1.6 1.4 1.2 1.0 0.8
Page 139 and 140: 250V 1MΩ 3x 2.2mF TTL 5V feedback
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Page 143 and 144: 5.2.2.1 Principle of Operation of t
Page 145 and 146: Figure 5.8: Photograph of the trapp
Page 147 and 148: 4.1.3. In an anti-Helmholtz trap, t
Page 149 and 150: Figure 5.11: Photograph of the hydr
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Page 157 and 158: Ionizer 500 l/s Turbo Pump Ion Opti
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Page 161 and 162: Z − Velocity (m/s) 100 60 30 0
Page 163 and 164: Atom Number 60 50 40 30 20 10 0.6 0
Page 165 and 166: scattered photon to extract informa
Page 167 and 168: where k1 · pi = − k2 · pi, wh
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Page 173 and 174: prevent the determination of the is
Page 175 and 176: (a) (b) time Figure 5.25: A 1D illu
Page 177 and 178: experiment, where a being is capabl
Page 179 and 180: potential position 2 x 243 nm Lα |
Page 181 and 182: Appendix 164
Page 183 and 184: y x V i Figure A.1: The geometry us
Page 185 and 186: Bibliography [1] H.J.MetcalfandP.va
Page 187 and 188: [17] Brian C. Sawyer, Benjamin L. L
Page 189 and 190: [34] R. Campargue. Progress in over
Page 191 and 192: [51] O. Carnal, M. Sigel, T. Sleato
Page 193 and 194: [70] Edvardas Narevicius, Adam Libs
Page 195 and 196: [87] Willis E. Lamb and Robert C. R
Page 197 and 198: [96] G.Gabrielse,N.S.Bowden,P.Oxley
Page 199 and 200: [110] N. Kolachevsky, J. Alnis, S.
Page 201 and 202: [125] Andreas Osterwalder, Samuel A
Page 203 and 204: [142] C. Cohen-Tannoudji, B. Diu, a
Page 205 and 206: [161] Paulo F. Bedaque, Aurel Bulga
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Experiments with Supersonic Beams as a Source of Cold Atoms

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