The best cesium clocks are good to ~one second every 300 million years,
now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >atoms in a matrix of laser light ? think of eggs resting in an egg carton
? are also achieving stunning levels of performance. Because lattice
clocks allow scientists to probe thousands of atoms at once, they can >perform precision measurements much faster than single-ion clocks. This >allows scientists to validate the clock performance over shorter time >periods and perform precision studies of the clock frequencies. NIST?s >lattice clocks would not have gained or lost a second had they started >running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on >optical lattice clocks were behind paywalls in my quick search, but >arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>atoms in a matrix of laser light ? think of eggs resting in an egg carton >>? are also achieving stunning levels of performance. Because lattice >>clocks allow scientists to probe thousands of atoms at once, they can >>perform precision measurements much faster than single-ion clocks. This >>allows scientists to validate the clock performance over shorter time >>periods and perform precision studies of the clock frequencies. NIST?s >>lattice clocks would not have gained or lost a second had they started >>running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- >einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on >>optical lattice clocks were behind paywalls in my quick search, but >>arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>? are also achieving stunning levels of performance. Because lattice >>>clocks allow scientists to probe thousands of atoms at once, they can >>>perform precision measurements much faster than single-ion clocks. This >>>allows scientists to validate the clock performance over shorter time >>>periods and perform precision studies of the clock frequencies. NIST?s >>>lattice clocks would not have gained or lost a second had they started >>>running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- >>einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on >>>optical lattice clocks were behind paywalls in my quick search, but >>>arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
As far as I know, NIST publications were planned to be publicly
available, but are not currently available to the great unwashed
masses for free.
"The NIST Plan for Providing Public Access to Results of Federally
Funded Research 2023 edition" ><https://nvlpubs.nist.gov/nistpubs/ir/2023/NIST.IR.8084e2023.pdf>
"Public Access to NIST Research"
<https://www.nist.gov/open>
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>atoms in a matrix of laser light ? think of eggs resting in an egg carton >>? are also achieving stunning levels of performance. Because lattice >>clocks allow scientists to probe thousands of atoms at once, they can >>perform precision measurements much faster than single-ion clocks. This >>allows scientists to validate the clock performance over shorter time >>periods and perform precision studies of the clock frequencies. NIST?s >>lattice clocks would not have gained or lost a second had they started >>running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- >einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on >>optical lattice clocks were behind paywalls in my quick search, but >>arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
On Fri, 17 Jul 2026 16:17:52 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>> now surpassed by optical lattice clocks.einsteins-general-relativity-millimeter-scale>
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>> atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>> ? are also achieving stunning levels of performance. Because lattice
clocks allow scientists to probe thousands of atoms at once, they can
perform precision measurements much faster than single-ion clocks. This >>>> allows scientists to validate the clock performance over shorter time
periods and perform precision studies of the clock frequencies. NIST?s >>>> lattice clocks would not have gained or lost a second had they started >>>> running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>> Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure-
The NIST pages are intended for the general public and most papers on
optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
As far as I know, NIST publications were planned to be publicly
available, but are not currently available to the great unwashed
masses for free.
"The NIST Plan for Providing Public Access to Results of Federally
Funded Research 2023 edition"
<https://nvlpubs.nist.gov/nistpubs/ir/2023/NIST.IR.8084e2023.pdf>
"Public Access to NIST Research"
<https://www.nist.gov/open>
It's always been hidden in plain sight, well preceeding 2023. The pdf
files have names of the form "<integer>.pdf", with no hint as to
what's inside.
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>> now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>> atoms in a matrix of laser light ? think of eggs resting in an egg carton >>> ? are also achieving stunning levels of performance. Because lattice
clocks allow scientists to probe thousands of atoms at once, they can
perform precision measurements much faster than single-ion clocks. This >>> allows scientists to validate the clock performance over shorter time
periods and perform precision studies of the clock frequencies. NIST?s
lattice clocks would not have gained or lost a second had they started
running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum
Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- >> einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on
optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium
vapor itself.
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years,
now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium
atoms in a matrix of laser light ? think of eggs resting in an egg carton >>> ? are also achieving stunning levels of performance. Because lattice
clocks allow scientists to probe thousands of atoms at once, they can
perform precision measurements much faster than single-ion clocks. This
allows scientists to validate the clock performance over shorter time
periods and perform precision studies of the clock frequencies. NIST?s
lattice clocks would not have gained or lost a second had they started
running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum
Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- >> einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on
optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium
vapor itself.
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>? are also achieving stunning levels of performance. Because lattice >>>clocks allow scientists to probe thousands of atoms at once, they can >>>perform precision measurements much faster than single-ion clocks. This >>>allows scientists to validate the clock performance over shorter time >>>periods and perform precision studies of the clock frequencies. NIST?s >>>lattice clocks would not have gained or lost a second had they started >>>running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure- >>einsteins-general-relativity-millimeter-scale>
The NIST pages are intended for the general public and most papers on >>>optical lattice clocks were behind paywalls in my quick search, but >>>arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium
vapor itself.
john larkin <jl@glen--canyon.com> wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:You heterodyne it with one line of a modelocked Ti:sapphire laser. The >Hall-Haensch frequency comb works by broadening the pulse spectrum to an >octave (by narrowing the pulses) and then locking a line on the high end to >the second harmonic of one at the low end.
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>> now surpassed by optical lattice clocks.einsteins-general-relativity-millimeter-scale>
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>> atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>> ? are also achieving stunning levels of performance. Because lattice
clocks allow scientists to probe thousands of atoms at once, they can >>>> perform precision measurements much faster than single-ion clocks. This >>>> allows scientists to validate the clock performance over shorter time >>>> periods and perform precision studies of the clock frequencies. NIST?s >>>> lattice clocks would not have gained or lost a second had they started >>>> running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>> Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure-
The NIST pages are intended for the general public and most papers on >>>> optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium
vapor itself.
That gives all the lines the same absolute stability (i.e. in hertz) as the >RF reference. That bit of extreme cleverness got them the 2005 Nobel
prize, and well deserved it was. (I know both of them slightly.)
Cheers
Phil Hobbs
On 18/07/2026 14:43, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 16:17:52 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>>> now surpassed by optical lattice clocks.einsteins-general-relativity-millimeter-scale>
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>>> atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>>> ? are also achieving stunning levels of performance. Because lattice >>>>> clocks allow scientists to probe thousands of atoms at once, they can >>>>> perform precision measurements much faster than single-ion clocks. This >>>>> allows scientists to validate the clock performance over shorter time >>>>> periods and perform precision studies of the clock frequencies. NIST?s >>>>> lattice clocks would not have gained or lost a second had they started >>>>> running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>>> Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure-
The NIST pages are intended for the general public and most papers on >>>>> optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
As far as I know, NIST publications were planned to be publicly
available, but are not currently available to the great unwashed
masses for free.
"The NIST Plan for Providing Public Access to Results of Federally
Funded Research 2023 edition"
<https://nvlpubs.nist.gov/nistpubs/ir/2023/NIST.IR.8084e2023.pdf>
"Public Access to NIST Research"
<https://www.nist.gov/open>
It's always been hidden in plain sight, well preceeding 2023. The pdf
files have names of the form "<integer>.pdf", with no hint as to
what's inside.
That is more a feature of the cursed content management system.
You can usually find stuff published in the open literature on arXiv.
Many academic journals encourage researchers to publish there (even ones >that have a paywall on the main site).
john larkin <jl@glen--canyon.com> wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:You heterodyne it with one line of a modelocked Ti:sapphire laser. The >Hall-Haensch frequency comb works by broadening the pulse spectrum to an >octave (by narrowing the pulses) and then locking a line on the high end to >the second harmonic of one at the low end.
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>> now surpassed by optical lattice clocks.einsteins-general-relativity-millimeter-scale>
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>> atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>> ? are also achieving stunning levels of performance. Because lattice
clocks allow scientists to probe thousands of atoms at once, they can >>>> perform precision measurements much faster than single-ion clocks. This >>>> allows scientists to validate the clock performance over shorter time >>>> periods and perform precision studies of the clock frequencies. NIST?s >>>> lattice clocks would not have gained or lost a second had they started >>>> running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>> Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure-
The NIST pages are intended for the general public and most papers on >>>> optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium
vapor itself.
That gives all the lines the same absolute stability (i.e. in hertz) as the >RF reference. That bit of extreme cleverness got them the 2005 Nobel
prize, and well deserved it was. (I know both of them slightly.)
Cheers
Phil Hobbs
On Sat, 18 Jul 2026 15:32:50 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@glen--canyon.com> wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:You heterodyne it with one line of a modelocked Ti:sapphire laser. The
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million years, >>>>> now surpassed by optical lattice clocks.einsteins-general-relativity-millimeter-scale>
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or strontium >>>>> atoms in a matrix of laser light ? think of eggs resting in an egg carton >>>>> ? are also achieving stunning levels of performance. Because lattice >>>>> clocks allow scientists to probe thousands of atoms at once, they can >>>>> perform precision measurements much faster than single-ion clocks. This >>>>> allows scientists to validate the clock performance over shorter time >>>>> periods and perform precision studies of the clock frequencies. NIST?s >>>>> lattice clocks would not have gained or lost a second had they started >>>>> running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the 'Quantum >>>>> Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure-
The NIST pages are intended for the general public and most papers on >>>>> optical lattice clocks were behind paywalls in my quick search, but
arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium
vapor itself.
Hall-Haensch frequency comb works by broadening the pulse spectrum to an
octave (by narrowing the pulses) and then locking a line on the high end to >> the second harmonic of one at the low end.
That gives all the lines the same absolute stability (i.e. in hertz) as the >> RF reference. That bit of extreme cleverness got them the 2005 Nobel
prize, and well deserved it was. (I know both of them slightly.)
Cheers
Phil Hobbs
OK, that's cool. A modelocked laser runs roughly 100 MHz but makes
such narrow pulses that it has harmonics in the optical range.
On Sat, 18 Jul 2026 16:30:53 +0100, Martin Brown
<'''newspam'''@nonad.co.uk> wrote:
On 18/07/2026 14:43, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 16:17:52 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 millioneinsteins-general-relativity-millimeter-scale>
years, now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or
strontium atoms in a matrix of laser light ? think of eggs resting >>>>>> in an egg carton ? are also achieving stunning levels of
performance. Because lattice clocks allow scientists to probe
thousands of atoms at once, they can perform precision measurements >>>>>> much faster than single-ion clocks. This allows scientists to
validate the clock performance over shorter time periods and
perform precision studies of the clock frequencies. NIST?s lattice >>>>>> clocks would not have gained or lost a second had they started
running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the
'Quantum Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks- measure-
The NIST pages are intended for the general public and most papers >>>>>> on optical lattice clocks were behind paywalls in my quick search, >>>>>> but arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
As far as I know, NIST publications were planned to be publicly
available, but are not currently available to the great unwashed
masses for free.
"The NIST Plan for Providing Public Access to Results of Federally
Funded Research 2023 edition"
<https://nvlpubs.nist.gov/nistpubs/ir/2023/NIST.IR.8084e2023.pdf>
"Public Access to NIST Research"
<https://www.nist.gov/open>
It's always been hidden in plain sight, well preceeding 2023. The pdf
files have names of the form "<integer>.pdf", with no hint as to
what's inside.
That is more a feature of the cursed content management system.
You can usually find stuff published in the open literature on arXiv.
Many academic journals encourage researchers to publish there (even ones >>that have a paywall on the main site).
All true, but NIST is a special case. By US law, US Government
publications cannot be copyrighted (because taxpayers already paid for
them), so NIST always has an archive where one can get a copy, even if
the article is also published in a formal journal behind a paywall.
So a typical approach is to search for an article in the usual ways, and
when the exact title is found, search for the title alone. This will
also bring up the relevant NIST archive URL.
Joe
On Sat, 18 Jul 2026 11:52:52 -0400, joegwinn wrote:
On Sat, 18 Jul 2026 16:30:53 +0100, Martin Brown
<'''newspam'''@nonad.co.uk> wrote:
On 18/07/2026 14:43, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 16:17:52 -0700, Jeff Liebermann <jeffl@cruzio.com> >>>> wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 million >>>>>>> years, now surpassed by optical lattice clocks.einsteins-general-relativity-millimeter-scale>
from <https://www.nist.gov/si-redefinition/second/second-future>: >>>>>>>
"Optical ?lattice clocks,? which embed ultracold ytterbium or
strontium atoms in a matrix of laser light ? think of eggs resting >>>>>>> in an egg carton ? are also achieving stunning levels of
performance. Because lattice clocks allow scientists to probe
thousands of atoms at once, they can perform precision measurements >>>>>>> much faster than single-ion clocks. This allows scientists to
validate the clock performance over shorter time periods and
perform precision studies of the clock frequencies. NIST?s lattice >>>>>>> clocks would not have gained or lost a second had they started
running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the
'Quantum Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks- >measure-
The NIST pages are intended for the general public and most papers >>>>>>> on optical lattice clocks were behind paywalls in my quick search, >>>>>>> but arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST >>>>>> web site somewhere.
Joe
As far as I know, NIST publications were planned to be publicly
available, but are not currently available to the great unwashed
masses for free.
"The NIST Plan for Providing Public Access to Results of Federally
Funded Research 2023 edition"
<https://nvlpubs.nist.gov/nistpubs/ir/2023/NIST.IR.8084e2023.pdf>
"Public Access to NIST Research"
<https://www.nist.gov/open>
It's always been hidden in plain sight, well preceeding 2023. The pdf >>>> files have names of the form "<integer>.pdf", with no hint as to
what's inside.
That is more a feature of the cursed content management system.
You can usually find stuff published in the open literature on arXiv. >>>Many academic journals encourage researchers to publish there (even ones >>>that have a paywall on the main site).
All true, but NIST is a special case. By US law, US Government
publications cannot be copyrighted (because taxpayers already paid for
them), so NIST always has an archive where one can get a copy, even if
the article is also published in a formal journal behind a paywall.
So a typical approach is to search for an article in the usual ways, and
when the exact title is found, search for the title alone. This will
also bring up the relevant NIST archive URL.
Joe
Nice tip, thanks. One can also often obtain a copy of journal articles by >contacting the lead author, which can work for papers not paid for by >taxpayers, which is the case for some of the papers on optical lattice >clocks and hyperfine transitions, of which there are at least 2 for 87Sr
and at least 1 for Yt and Al. I decided I did not to try to figure out
how they get millihertz linewidth at visible light frequencies when I got
to the part about interaction with the nucleus allowing a doubly-
prohibited state. The part about keeping an array of atoms at ~2 uK is >easier to understand :-).
On 19/07/2026 2:29 am, john larkin wrote:
On Sat, 18 Jul 2026 15:32:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
john larkin <jl@glen--canyon.com> wrote:
On Fri, 17 Jul 2026 14:32:58 -0400, joegwinn@comcast.net wrote:You heterodyne it with one line of a modelocked Ti:sapphire laser. The
On Fri, 17 Jul 2026 15:11:51 GMT, Glen Walpert <nospam@null.void>
wrote:
The best cesium clocks are good to ~one second every 300 millioneinsteins-general-relativity-millimeter-scale>
years,
now surpassed by optical lattice clocks.
from <https://www.nist.gov/si-redefinition/second/second-future>:
"Optical ?lattice clocks,? which embed ultracold ytterbium or
strontium
atoms in a matrix of laser light ? think of eggs resting in an egg >>>>>> carton
? are also achieving stunning levels of performance. Because lattice >>>>>> clocks allow scientists to probe thousands of atoms at once, they can >>>>>> perform precision measurements much faster than single-ion clocks. >>>>>> This
allows scientists to validate the clock performance over shorter time >>>>>> periods and perform precision studies of the clock frequencies.
NIST?s
lattice clocks would not have gained or lost a second had they
started
running at the Big Bang, roughly 13.8 billion years ago."
----
The 87Sr version of the optical lattice clock was used in the
'Quantum
Sensor Breakthrough...' thread here, as well as:
.<https://www.nist.gov/news-events/news/2022/02/jila-atomic-clocks-measure-
The NIST pages are intended for the general public and most papers on >>>>>> optical lattice clocks were behind paywalls in my quick search, but >>>>>> arXiv.org has some details of current research:
.<https://arxiv.org/abs/2506.18958>
Glen
Articles written by US Government entities like NIST cannot be
copyrighted, and all such articles are available gratis on the NIST
web site somewhere.
Joe
Given a narrow-bandwidth optical source, how does one divide it down
to electronic frequencies?
Rubidium clocks use some optical-microwave interaction in the rubidium >>>> vapor itself.
Hall-Haensch frequency comb works by broadening the pulse spectrum to an >>> octave (by narrowing the pulses) and then locking a line on the high
end to
the second harmonic of one at the low end.
That gives all the lines the same absolute stability (i.e. in hertz)
as the
RF reference.ÿ That bit of extreme cleverness got them the 2005 Nobel
prize, and well deserved it was. (I know both of them slightly.)
Cheers
Phil Hobbs
OK, that's cool. A modelocked laser runs roughly 100 MHz but makes
such narrow pulses that it has harmonics in the optical range.
That's got it sideways. A pulsed laser produces very narrow pulses -
Dirac idealised them as infinitely narrow pulses - and the Fourier
transform of a string of narrow pulses has a harmonic content of all the harmonics up to a limit set by the width of the pulse (a Dirac pulse has zero width as you'd expect in a theoretician's idealisation). If the harmonics go up to the frequency of the laser line itself and you get
the interaction right, you can get a frequency comb where each of the harmonics is an integral sub-multiple of the optical reference frequency.
Just having harmonics in the right frequency range isn't enough - you
need a mechanism to lock the repetition rate to the right frequency
Phil clearly understands what that mechanism is. I equally clearly don't.
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