Quantum projection noise limited interferometry with coherent atoms in a Ramsey type setup

TL;DR

This paper demonstrates quantum projection noise limited performance in a Ramsey interferometer with coherent atoms, using a stable Sagnac setup and Raman transitions, paving the way for enhanced atom interferometry sensitivity.

Contribution

It presents the first experimental realization of a Ramsey interferometer operating at the quantum projection noise limit with coherent atoms.

Findings

Achieved quantum projection noise limited interferometry with coherent atoms.

Demonstrated potential for observing squeezing effects in atom lasers.

Established a stable experimental setup for fundamental noise level measurements.

Abstract

Every measurement of the population in an uncorrelated ensemble of two-level systems is limited by what is known as the quantum projection noise limit. Here, we present quantum projection noise limited performance of a Ramsey type interferometer using freely propagating coherent atoms. The experimental setup is based on an electro-optic modulator in an inherently stable Sagnac interferometer, optically coupling the two interfering atomic states via a two-photon Raman transition. Going beyond the quantum projection noise limit requires the use of reduced quantum uncertainty (squeezed) states. The experiment described demonstrates atom interferometry at the fundamental noise level and allows the observation of possible squeezing effects in an atom laser, potentially leading to improved sensitivity in atom interferometers.