[time-nuts] New atomic clock

[David McQuate]

The article was accepted for publication on Feb 22, 2012    in    
Physical Review Letters.
The March issue has already been published, so maybe this one will be in 
the April issue.

The title is
Single-ion nuclear clock for metrology at the 19th decimal place

Authors:
C. J. Campbell, A. G. Radnaev, A. Kuzmich, V. A. Dzuba, V. V. Flambaum, 
and A. Derevianko

If you Google the title, I think you'll be able to find a pdf at 
arxiv.org/pdf/1110.2490

The article discusses many factors necessary to obtain a fractional 
inaccuracy approaching 1e-19.
The technique uses the 7.6 eV (ie 1.8377e15 Hz or 163 nm wavelength) 
nuclear magnetic-dipole
transition in a single thorium 229  ion (3+).  This paper does not 
report experimental results--I don't
think the scheme has yet been implemented.

"A pair of Th(3+) ions would be stored in a linear rf trap where strong 
rf confinement places both ions
on the trap axis.  With a trap of radius 700 um, and drive frequency of 
25 MHz..."

The 163nm interrogation light "might be generated by a multi-stage 
sum-frequency generation of
visible or NIR light within nonlinear crystals...with the fundamental 
frequency locked to an ultra-stable
optical resonator."

Laser cooling is used, using a 1088nm wavelength.  The same wavelength 
is used to suppress the
Stark effect by three orders of magnitude.

Doppler shifts resulting from interrogation are reduced by alternating 
the direction of the probe beam.

A gravitational shift of 1e-19 will result from a difference in height 
of 1 mm.

A two week averaging time is suggested.

Dave
wa8ywq

On 3/13/2012 11:37 AM, Joseph Gray wrote:
> http://www.news.com.au/technology/sci-tech/nucelar-clock-100-times-more-accurate-than-atomic-clock/story-fn5fsgyc-1226297068083#ixzz1osFDYtyb
>
> I didn't see a link to a more detailed article. This one tells you
> almost nothing.
>
> Joe Gray
> W5JG
>
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