We present a technique to excite Raman transitions with minimum phase noise. A phase modulator generates the Raman beams and a long calcite crystal rotates the polarization of the sidebands by 90° with respect to the carrier. That polarization converts the destructive interference of the Raman pairs into constructive interference, opening the possibility to drive both co-propagating and counter-propagating transitions at high detuning with the same setup. The technique has low phase noise and a low sensitivity to vibrations or temperature fluctuations. We apply it to drive velocity insensitive Raman transitions. The crystal can be also configured to filter out one of the sidebands.
Atomic interferometers are often affected by magnetic field fluctuations. Using the clock transition at zero magnetic field minimizes the effect of these fluctuations. There is another transition in rubidium that minimizes the magnetic sensitivity at 3.2 Gauss. We combine the previous two transitions to obtain minimum magnetic sensitivity at a tunable magnetic field between 2.2 and 3.2 Gauss. The two interferometers evolve independently from each other and we control the magnetic sensitivity by changing the population in both transitions with a microwave pulse.
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