[time-nuts] Yb clock - NPR Story on Atomic Clocks

[Tom Van Baak]

Hi Hal,

About Moore's law -- to appreciate how far this Time & Frequency field has come, the very first paper in the NIST archive, from 1949, describes the 23.87 GHz ammonia molecule clock, which was accurate to 1e-7 (yes, less than laboratory quartz or precision pendulum):

"An Atomic Standard of Frequency and Time"
http://tf.boulder.nist.gov/general/pdf/1.pdf

For those computer history nuts among us, don't miss the preceding article in the PDF which mentions NBS/NIST's first computer (2.75 kbyte memory, 864 microsecond addition time).

Comparing the ammonia clock with the Yb clock, that's 11 decades of atomic clock improvement over a span of 60 years. Meanwhile my laptop has 6 or 7 decades more memory and cpu speed than the NBS computer from 60 years ago. You see who's winning the Moore's law race...

/tvb

----- Original Message ----- 
From: "Hal Murray" <hmurray at megapathdsl.net>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, August 23, 2013 10:39 AM
Subject: Re: [time-nuts] Yb clock - NPR Story on Atomic Clocks


> 
>> Optical clocks keep getting a little bit better each time they try this or
>> that. They still have a way to go before you will have one running 24/7/365
>> without it costing more than even NIST can afford to spend.  
> 
> From Daniel Kleppner's Time Too Good to Be True
> Physics Today, March 2006
>  http://scitation.aip.org/journals/doc/PHTOAD-ft/vol_59/iss_3/10_1.shtml
> 
> The accuracy of these clocks has improved by roughly a factor of 10 every 
> decade since they were introduced in the mid-1950s and in the next few years 
> the accuracy is expected to reach 1 part in 10E16.
> 
> Exponential, just like Moore's law.
>