[HN Gopher] Two atomic clocks have been quantum entangled for th... ___________________________________________________________________ Two atomic clocks have been quantum entangled for the first time Author : lysp Score : 12 points Date : 2022-09-09 15:29 UTC (7 hours ago) (HTM) web link (www.newscientist.com) (TXT) w3m dump (www.newscientist.com) | colejohnson66 wrote: | From /r/science[0]: https://news.mit.edu/2020/atomic-clock-time- | precise-1216 | | [0]: | https://old.reddit.com/r/science/comments/x8khxg/two_atomic_... | rolph wrote: | MIT news: | | https://news.mit.edu/2020/atomic-clock-time-precise-1216 | | seems to be the better link, also reveals subject is a 2020 | discovery, was also published in Nature: | | https://www.nature.com/articles/s41586-022-05088-z [paywall] | | "Abstract | | Optical atomic clocks are our most precise tools to measure time | and frequency1,2,3. Precision frequency comparisons between | clocks in separate locations enable one to probe the space-time | variation of fundamental constants4,5 and the properties of dark | matter6,7, to perform geodesy8,9,10 and to evaluate systematic | clock shifts. Measurements on independent systems are limited by | the standard quantum limit; measurements on entangled systems can | surpass the standard quantum limit to reach the ultimate | precision allowed by quantum theory--the Heisenberg limit. | Although local entangling operations have demonstrated this | enhancement at microscopic distances11,12,13,14,15,16, | comparisons between remote atomic clocks require the rapid | generation of high-fidelity entanglement between systems that | have no intrinsic interactions. Here we report the use of a | photonic link17,18 to entangle two 88Sr+ ions separated by a | macroscopic distance19 (approximately 2 m) to demonstrate an | elementary quantum network of entangled optical clocks. For | frequency comparisons between the ions, we find that entanglement | reduces the measurement uncertainty by nearly \\(\sqrt{2}\\), the | value predicted for the Heisenberg limit. Today's optical clocks | are typically limited by dephasing of the probe laser20; in this | regime, we find that entanglement yields a factor of 2 reduction | in the measurement uncertainty compared with conventional | correlation spectroscopy techniques20,21,22. We demonstrate this | enhancement for the measurement of a frequency shift applied to | one of the clocks. This two-node network could be extended to | additional nodes23, to other species of trapped particles or-- | through local operations--to larger entangled systems. | | " | kalupa wrote: | https://archive.ph/VVwbl | | EDIT: ah, dang, also doesn't work | dtx1 wrote: | paywalled. 12ft.io doesnt help. | alexalx666 wrote: | 12ft is awesome, thanks! ___________________________________________________________________ (page generated 2022-09-09 23:00 UTC)