Extended Data Figure 1: Dependence of contrast on absolute light shift compensation.
For 30ħk, the contrast as a fraction of its maximum value is plotted as a function of the asymmetry between the red and blue sidebands for one of the atom optics laser beams. To change the sideband asymmetry, we adjust the temperature of one of the frequency doubling crystals while keeping the sidebands of the second atom optics laser beam symmetric. Where Pred and Pblue are the respective optical powers in the red and blue sidebands, we define an asymmetry parameter 1 − (Pred/Pblue). Since the blue sideband is used to drive the Bragg transitions, we keep Pblue fixed in order to maintain constant Rabi frequency. This prevents us from reaching large negative values of the asymmetry parameter, because there is only enough total optical power available to increase Pred slightly without suppressing Pblue. In order to achieve a more negative effective value of the asymmetry parameter, we suppress the power in the carrier to half its usual amount for the one negative point in the plot. The carrier is blue detuned, so decreasing its power pulls the absolute light shift in the same direction as decreasing Pblue. To account for this, we plot the fractional contrast versus the effective asymmetry parameter that would yield the same light shift as the one that we implement, but at a fixed carrier power. The observed dependence of contrast on the sideband asymmetry indicates the importance of absolute light shift compensation for LMT interferometry. Error bars, 1σ.
