English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The fundamental limits of atomic fountains as operational clocks areconsidered. Four rubidium fountains in operation at the U.S. Naval Observatoryfor over 5.5 years have demonstrated unprecedented long-term stability forcontinuously running clocks [1,2]. With only these rubidium fountains, apost-processed timescale can be created that demonstrates superior long-termperformance to any individual clock by compensating for occasional frequencysteps. By comparing to the world's primary standards we demonstrate instabilityof this rubidium fountain timescale reaching the mid $10^{-17}$'s and zerodrift at the level of $1.3 \times 10^{-19}$/day. We discuss fundamental limitsdue to common mode behaviour or individual fountain performance that cannot becorrected.

Microwave-clock timescale with instability on order of $10^{-17}$