A compact micro-wave synthesizer for transportable cold-atom interferometers

TL;DR

This paper reports the development of a compact, low-noise microwave synthesizer tailored for transportable cold-atom interferometers, significantly enhancing portability and performance for inertial sensing applications.

Contribution

The paper introduces a novel, miniaturized microwave synthesizer with low phase noise, optimized for portable atom interferometers, advancing field-deployable quantum sensing technology.

Findings

Residual phase noise of -65 dBrad^2/Hz at 10 Hz offset

White phase noise around -120 dBrad^2/Hz above 10 kHz

Phase noise impact below sensitivity threshold of current sensors

Abstract

We present the realization of a compact micro-wave frequency synthesizer for an atom interferometer based on stimulated Raman transitions, applied to transportable inertial sensing. Our set-up is intended to address the hyperfine transitions of Rubidium 87 atoms at 6.8 GHz. The prototype is evaluated both in the time and the frequency domain by comparison with state-of-the-art frequency references developed at LNE-SYRTE. In free-running mode, it features a residual phase noise level of -65 dBrad$^2.Hz^{-1} at 10-Hz offset frequency and a white phase noise level in the order of -120 dBrad^2.Hz^{-1} for Fourier frequencies above 10 kHz. The phase noise effect on the sensitivity of the atomic interferometer is evaluated for diverse values of cycling time, interrogation time and Raman pulse duration. To our knowledge, the resulting contribution is well below the sensitivity of any demonstrated cold atom inertial sensors based on stimulated Raman transitions. The drastic improvement in terms of size, simplicity and power consumption paves the way towards field and mobile operations.