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Today’s topic

• Alignment• Polarization Mechanism

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Optics alignment

Requirement:•Make sure the laser is parallel, no divergent, and clear edges, good shapes•Make sure the reflection is near the fiber, but not coincide •Make sure all of the spots is overlapped•Make sure the laser injected into the oven is horizontal

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Alignment steps•Use cross test laser to adjust the mirror and cube’s position•Clean the fiber and mount it, use cross laser in order to all of the modules is in a plane•Mount the lens and adjust the focus, make sure the laser is parallel•Rotate the cube, make sure the horizontal position of reflection from cube close to fiber and not cover the laser•Adjust two screws of the cube(Synchronization), make sure the vertical position of reflection from cube close to fiber•Adjust the quarter wave plate and make sure the laser will pass through the center and the reflection of it is close to fiber•Adjust the 2.5” mirror, make sure the spot is in the center of the oven’s first mirror, and let the reflection of it is close to fiber•Adjust the 3” mirror and let its spot is coincide above,•Adjust another two way like above steps, make sure six spot is coincide•Adjust the quarter wave plate right side to make sure the laser will pass it and the reflection of it is well overlapped with other spotsAdjust the mirror front the oven, make sure the laser will direct entry the oven

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Polarization MechanismBecause of the magnetic field and right circularly polarized light, Rb atom can be excited from 5S1/2,M=-1/2 to 5P1/2,M=1/2

Isotropically light->limit efficiency->N2 for quenching

Ignore the nuclear spin

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F=I+SI=5/2 for 85Rb

Hyperfine splitting

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Spin-Exchange

Na-3He~ near 100%K-3He ~4 photons are required to produce a single polarized 3He nucleusRb-3He ~ 50 photons are required

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Another method

Direct optical pumpingUse 1.08μm circularly polarized light23S1 (metastable) -> 23P0

Shortcoming: the density of 3He is very low to maintain RF discharge

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Thanks!