Measurement of a ${}^7$Li tune-out wavelength by phase-patterned atom interferometry

Abstract

Atom interferometers typically use the total populations the interferometer's output ports as the signal, but finer spatial structure can contain useful information. We pattern a matter-wave phase profile onto an atomic sample. An interferometer translates the phase into a measurable pattern in the atomic density that we use perform the first direct precision measurement of the ${}^7$Li tune-out wavelength near 671 nm. Expressed as a detuning from the $|2S_{1/2},F=2⟩\to |2P_{1/2},F^{\prime }=2⟩$ transition, we find 3329.3(1.4) MHz for the tensor-shifted tune out of the $|2S_{1/2},F=2,m_F=0⟩$ state with ${\sigma }^{\pm }$ light polarization and 3310.1(4.9) MHz for the tune out of the the scalar polarizability. This technique may be generalized for directly sensing spatially varying phase profiles.

14 pages, 11 figures