Efficient state-symmetric beamsplitters and mirrors for atom interferometers using optimized pulses

Atom interferometers that employ atoms in superpositions of different electronic states are sensitive to any noise that affects these superposed states differently. Resilience to such noise results from using superpositions where the atomic states differ in momentum only, but implementation of such 'state-symmetric' diffraction can lead to population loss into unwanted states and restricts the atomic velocity acceptance of the interferometer. In this paper, by varying the laser intensities and phases as functions of time, we present optimized pulses designed for use in state-symmetric interferometers that overcome these restrictions. We extend this optimization to multi-pulse sequences designed to increase the interferometer area and demonstrate significant improvements in the fringe visibility compared with sequences of pi/2 and pi pulses. We discuss the limits on the temperature of the atomic source required for efficient atomic diffraction and show how optimized pulse sequences enable efficient diffraction with considerably warmer clouds, hence reducing the need for velocity selection and increasing the measurement signal-to-noise ratio.