[time-nuts] Frequency processing scheme of HP5065vapourrubidium standard

[Magnus Danielson]

From: Normand Martel <martelno at yahoo.com>
Subject: Re: [time-nuts] Frequency processing scheme of HP5065vapourrubidium standard
Date: Tue, 7 Nov 2006 17:25:19 -0800 (PST)
Message-ID: <20061108012519.4843.qmail at web50712.mail.yahoo.com>

> Thanks! very interesting articles!!!
> 
> But something bugs me... In both fountains and single
> ion mercury standards, lasers are used to COOL DOWN
> atoms...
> 
> How is it possible? Lasers are energy sources, and (at
> least for me), anything that is hit by a laser will
> get warm, not cold!

The short story is that you just push the atoms hard enougth with the pressure
of the photons. This have been used for many purposes and has infact been in
debate for a very long time. I even beleive the old greeks where into the
debate. Ah well. Basically you create an optical melass. Temperature is a
measure on the energy will to move around in Brownian motion. If you press hard
on something that wants to move around, that excess energy will be forced out
of that part of the system.

However, there is more happening in there which can't be explained by just the
pressure of the photons. It is the Sisyphys cooling effect, in which atoms too
much to the "left" (assuming a left-right scale of things) feels a pressure to
move "right" by the phase of the optical pumping. It is forced to climb the
hill continously.

Ion traps acheive about the same thing but using a different mechanism.

Above is very sloopy explanations, just to give you a very rought feel, but you
can get a better understandning than this. A good reading could be:
http://physics.nist.gov/News/Nobel/NobelLec.pdf

It's not every day that one has a reason to refer to a Nobel Lecture, but this
one felt relevant. :-)

Cheers,
MAgnus