A new photon recoil experiment: towards a determination of the fine structure constant
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- Müller, H., Chiow, SW., Long, Q. et al. Appl. Phys. B (2006) 84: 633. doi:10.1007/s00340-006-2279-x
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We report on progress towards a measurement of the fine structure constant α to an accuracy of 5×10-10 or better by measuring the ratio h/mCs of the Planck constant h to the mass of the cesium atom mCs. Compared to similar experiments, ours is improved in three significant ways: (i) simultaneous conjugate interferometers, (ii) multi-photon Bragg diffraction between same internal states, and (iii) an about 1000-fold reduction of laser phase noise to -138 dBc/Hz. Combining that with a new method to simultaneously stabilize the phases of four frequencies, we achieve 0.2 mrad effective phase noise at the location of the atoms. In addition, we use active stabilization to suppress systematic effects due to beam misalignment.