Splitting the Raman beamsplitter

TL;DR

This paper introduces a novel atom interferometry method that splits the beamsplitter into two steps, achieving high efficiency and enabling large momentum transfer, which enhances precision measurements.

Contribution

The authors develop a two-step beamsplitter technique using microwave and optical adiabatic passage, allowing high-efficiency large-momentum transfer in atom interferometry.

Findings

Achieved 99% efficiency per $\hbar k$ of momentum separation.

Demonstrated up to 16$\hbar k$ momentum splitting with free-fall times.

Realized a resonant interferometer with over 400$\hbar k$ total momentum transfer.

Abstract

We present an atom interferometry technique in which the beamsplitter is split into two separate operations. A microwave pulse first creates a spin-state superposition, before optical adiabatic passage spatially separates the arms of that superposition. Despite using a thermal atom sample in a small ($600 \, \mu$m) interferometry beam, this procedure delivers an efficiency of $99\%$ per $\hbar k$ of momentum separation. Utilizing this efficiency, we first demonstrate interferometry with up to $16\hbar k$ momentum splitting and free-fall limited interrogation times. We then realize a single-source gradiometer, in which two interferometers measuring a relative phase originate from the same atomic wavefunction. Finally, we demonstrate a resonant interferometer with over 100 adiabatic passages, and thus over $ 400 \hbar k$ total momentum transferred.