Measurement of a 7Li tune-out wavelength by phase-patterned atom interferometry

Atom interferometers typically use the total populations at the interferometer's output ports as the signal, but useful information can be encoded into spatial phase patterns. An interferometer translates the phase pattern into a measurable pattern in the atomic density that we use to perform a direct precision measurement of the Li-7 tune-out wavelength near 671 mm Expressed as a detuning from the vertical bar 2S(1/2), F = 2 > ->vertical bar 2P(1/2), F' = 2 > transition, we find 3329.5(1.4) MHz for the tensor-shifted tune out of the vertical bar 2S(1/2), F = 2, m(F) = 0 > state with sigma(+/-) light polarization and 3310.6(4.9) MHz for the tune out of the scalar polarizability. This technique may be generalized for directly sensing spatially varying phase profiles.