  Correlating the signals from simultaneous atom interferometers has enabled
some of the most precise determinations of fundamental constants. Here, we show
that multiple interferometers with strategically chosen initial conditions
("offset simultaneous conjugate interferometers" or OSCIs) can provide
multi-channel readouts that amplify or suppress specific effects. This allows
us to measure the photon recoil, and thus the fine structure constant, while
being insensitive to gravity gradients, general acceleration gradients, and
unwanted diffraction phases - these effects can be simultaneously monitored in
other channels. An expected 4-fold reduction of sensitivity to spatial
variations of gravity (due to higher-order gradients) and a 6-fold suppression
of diffraction phases paves the way to measurements of the fine structure
constant below the 0.1-ppb level, or to simultaneous sensing of gravity, the
gravity gradient, and rotations.
