Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

On Fri, 15 Dec 2017 17:17:31 +0100 Mike Cook wrote: > > The original paper in question is [1]. As with the nitrogen vacancy > > clocks, which also trap nitrogen within a Carbon lattice, these have the > > drawback of quite high temperature coefficients, Harding et al

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

> Le 15 déc. 2017 à 14:06, Attila Kinali a écrit : > > On Fri, 8 Dec 2017 09:40:29 -0800 > Tom McDermott wrote: > >> Researchers at Oxford U. have fabricated an atomic reference based on >> a single nitrogen molecule inside a 60-atom carbon sphere

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

On Fri, 8 Dec 2017 09:40:29 -0800 Tom McDermott wrote: > Researchers at Oxford U. have fabricated an atomic reference based on > a single nitrogen molecule inside a 60-atom carbon sphere ("Fullerene"). > The cage of carbon isolates the nitrogen from external electric fields,

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Citerar Mark Sims : In the standards definitions that include "at sea level", the question these days is "which sea level?". As ocean temperature changes sea level will change (except maybe in Washington DC). Will the standards be amended to include something like

[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

A 30 cm daily vertical offset is pretty typical. I've seen over 45 cm. Horizontal offsets are usually less than +/- 75 mm per day with the longitude displacement typically twice the latitude displacement. Heather uses a standard model (see http://geodesyworld.github.io/SOFTS/solid.htm) to

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Checkhttps://en.wikipedia.org/wiki/Earth_tide According to that, a foot of motion is easily plausible. The Wiki article says that displacements around a meter in the solid crust can be seen over the right intervals. This must wreak havoc in VLBI geodesy work, except that for some in the

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Hi Just as there are Time Nuts, there are Tide Nuts (I suppose it’s capitalized …). There is a a lot of data out there on just what sort of solid tides one might see at this or that point. Bob > On Dec 10, 2017, at 7:29 AM, Azelio Boriani wrote: > > Is that a

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Is that a Trimble Thunderbolt? Is there a way to compute the uncertainties? On Sun, Dec 10, 2017 at 2:42 AM, Tom Holmes wrote: > Mark... > You're place really moved a foot in 48 hours? Impressive and scary! > > From Tom Holmes, N8ZM > >> On Dec 9, 2017, at 8:19 PM, Mark Sims

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Mark... You're place really moved a foot in 48 hours? Impressive and scary! >From Tom Holmes, N8ZM > On Dec 9, 2017, at 8:19 PM, Mark Sims wrote: > > Which gets real fun with things like solid earth tides getting involved. > Lady Heather can now calculate and plot solid

[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Which gets real fun with things like solid earth tides getting involved. Lady Heather can now calculate and plot solid earth tides. Over the last 48 hours my place moved up/down 315 mm and gravity changed 186 microgals... and that was a rather stable period. -- > A 1

[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Yep, to paraphrase Bunker Hunt's "a billion dollars ain't what it used to be"... a nanosecond (or picosecond) ain't what it used to be. Things that used to be insignificant n'th order theoretical nuisances are now very real significant problems. > But it's not one-to-one as

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Mark, > In the standards definitions that include "at sea level", the question these > days is "which sea level?". Chris, > So does that mean e.g. NIST and BIPM need to measure the acceleration at > their respective locations to within parts in 10^17 or 10^18 in order to > compare their

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Hi If the frequency sensitivity is 1x10^-13 / G you don’t need a lot of precision in your measurement of G. The same issues apply to things like magnetic field and the rest. Bob > On Dec 9, 2017, at 4:02 PM, Chris Caudle wrote: > > On Sat, December 9, 2017 2:39 pm,

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Hi, On 12/09/2017 10:02 PM, Chris Caudle wrote: On Sat, December 9, 2017 2:39 pm, Magnus Danielson wrote: The standard acceleration is internationally agreed at 3rd CGPM in 1901 to be 9.80665 m/s^2. So does that mean e.g. NIST and BIPM need to measure the acceleration at their respective

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

On Sat, December 9, 2017 2:39 pm, Magnus Danielson wrote: > The standard acceleration is internationally agreed at 3rd CGPM in 1901 > to be 9.80665 m/s^2. So does that mean e.g. NIST and BIPM need to measure the acceleration at their respective locations to within parts in 10^17 or 10^18 in order

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Hi, On 12/09/2017 09:13 PM, Bob kb8tq wrote: Hi I suspect that at the practical level, you define standard atmospheric pressure, standard gravity, standard magnetic field ….. and on down the list. At some point “sea level” becomes a redundant expression. The standard acceleration is

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Hi I suspect that at the practical level, you define standard atmospheric pressure, standard gravity, standard magnetic field ….. and on down the list. At some point “sea level” becomes a redundant expression. Bob > On Dec 9, 2017, at 2:14 PM, Mark Sims wrote: > > In

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

On 12/9/17 11:14 AM, Mark Sims wrote: In the standards definitions that include "at sea level", the question these days is "which sea level?". As ocean temperature changes sea level will change (except maybe in Washington DC). Will the standards be amended to include something like "at sea

[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

In the standards definitions that include "at sea level", the question these days is "which sea level?". As ocean temperature changes sea level will change (except maybe in Washington DC). Will the standards be amended to include something like "at sea level in 1990" or will the value being

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Hi If you dig back into the various papers on the subject (and the proceedings that log the post paper questions) the issue of “can we trust the implementation?” does indeed come up. It’s come up for at least the last 50 years that I’m aware of. The basic argument runs that for fundamental

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

So we leave the scientific considerations and delve into the philosophical basis.  Somewhere down the line, a standard has to be established, to which all others can be compared.  How good this standard is doesn't matter, as long as it's stable.  But how does one measure stability?  Against

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

There is a piece missing for me in the articles I have found on new atomic standards. This is what I (think I) do understand: Quantum properties of the atoms can be interrogated using various RF or optical means to servo the frequency of an oscillator (which could be a laser based optical

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

I saw that about the N atom trapped inside a C60 molecule, but also took note of the present cost of the material. I wonder how much is going to be required to make a good standard. Dana On Fri, Dec 8, 2017 at 11:40 AM, Tom McDermott wrote: > There's an interesting

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

https://www.google.com/amp/s/spectrum.ieee.org/semiconductors/materials/to-build-the-worlds-smallest-atomic-clock-trap-a-nitrogen-atom-in-a-carbon-cage.amp.html > On Dec 8, 2017, at 10:38 AM, Ulrich Rohde via time-nuts > wrote: > > Impressive, Ulrich > > In a message

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Impressive, Ulrich    In a message dated 12/8/2017 12:41:23 PM Eastern Standard Time, tom.n...@gmail.com writes:   There's an interesting article in the December 2017 issue of IEEE Spectrum. Researchers at Oxford U. have fabricated an atomic reference based on a single nitrogen molecule inside

[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

There's an interesting article in the December 2017 issue of IEEE Spectrum. Researchers at Oxford U. have fabricated an atomic reference based on a single nitrogen molecule inside a 60-atom carbon sphere ("Fullerene"). The cage of carbon isolates the nitrogen from external electric fields, and