Performance demonstration of a compact, single optical frequency Cesium beam clock for space applications

Abstract

Observatoire de Neuchâtel has developed a compact opticallypumped cesium beam frequency standard in the frame of an ESA-ARTES 5 project. The simplest optical scheme, which is based on a single optical frequency for both preparation and detection processes of atoms, has been chosen to fulfill reliability constraints of space applications. With the last evolution of our laboratory demonstrator, we have measured a frequency stability of σ σ σ σ y =1.14x10 -12 τ τ τ τ -1/2 , which is compliant with the Galileo requirement and our frequency stability goal of σ σ σ σ y =1x10 -12 τ τ τ τ -1/2 . Present performance limitations are discussed and further improvements are proposed to possibly increase the frequency stability.

High-performance laser-pumped rubidium frequency standard for satellite navigation

“…We have demonstrated a compact Rb clock with a shortterm stability of 4 × 10 213 t 21/2 and medium-term stability ,1 × 10 214 at 10 4 s. This is comparable to stabilities of bigger clocks previously demonstrated [3,4,6], but from a much more compact PP and with a simple scheme using CW operation with one single laser frequency only. The demonstrated clock also widely relies on refined implementation of technologies already qualified for space applications, which is relevant in view of future clocks for space navigation and telecommunication.…”

“…Even cold atom clocks or optical clocks proposed for space applications target outlines of 1 m 3 volume, 230 kg mass, and 450 W power consumption [5]; hence a trade-off must be made between stability and portability. Recently developed portable standards, such as the passive hydrogen maser (SPHM) [4] or laser-pumped Cs beam clocks (LPCs) [6], exhibit a reasonable trade-off with volume (13 , V , 28 dm 3 ), mass (8 , m , 18 kg), power consumption (30 , P , 80 W) and stability (7 × 10 213 , s y (1 s) , 1.5 × 10 212 and 1 × 10 214 , s y (10 4 s) , 3 × 10 214 ). Here we show that our simple and compact, continuouswave (CW) laser-pumped double-resonance (DR) Rb clock stability outperforms that of LPCs standards up to 1000 s, and is comparable to coldatom portable clocks [3] or the SPHM, but from a physics package (PP) with volume of ,1 dm 3 only in our case.…”

In-depth analysis of the frequency stability of optically pumped cesium beam frequency standards

“…In (14), H depends on three variable parameters : I bg , b or rather bτ 0 , and ω m T 0 . τ 0 is the atomic time of flight across one arm of the cavity, length l, at the most probable velocity in the oven.…”

“…We have applied the previous analysis to the atomic resonator OSCAR developed by ON (Neuchâtel Observatory) [7] [14]. The exercise consists in determining the useful elements in equation (13): T 0 from the oven temperature and the length between the arms of the cavity, I 0 from the peak to valley detected signal, F* from (5)… and finally the optimum value of H 1/2 .…”

Proposal of rubidium atomic beam clock based on lamp pumped and fluorescence detection

“…With the development of the diode lasers, a few groups in the world started working on the laser-pumped cesium and rubidium beam clocks [3][4][5][6][7]. The main advantages are the higher utilization rates of the atoms and the more compact design.…”