M1L1e.txt

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# Captions for 8.422x module
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Well again, we have two limiting cases.
One case is when this potential or optical lattice
is really deep.
Deep means that atoms are sitting deep in the potential,
and they can oscillate around, but they cannot jump over
to the next potential.
So in this situation, you would say, well, that's evolving,
nothing happens, the atom just stays put.
But what is boring for some of you
is exciting for some others, because these atoms
are exquisitely controlled.
They cannot collide.
They cannot know interact with other atoms.
So these are really the most ideal situations
you can imagine for atoms.
Of course, if you have less than one atom per site, and this
is the way how you want to prepare atoms for the most
accurate interrogations.
And you can build atomic clocks, optical atomic clocks,
based on atoms insulated in such lattice, which approach now
10 to the minus 17 accuracy.
Well, if you excite-- if you drive a clock transition,
if you take the atom from the count with the excited state,
you may face the situation I mentioned earlier,
that the periodic potential for the count in excited state
are different.
And that would actually interfere with your clock,
because the clock frequency depends now
on what the lattice is doing to your atoms.
However, and we discussed that in week four,
there are what people call magic wavelenghts,
where you pick a certain wavelength
for your optical lattice, where the periodic potential is
absolutely the same for counting the excited state.
So that means you have then the perfect decoupling
between the ticking of the clock--
the internal structure of the atom--
and the mechanical motion of the atoms in the potential.
And in that situation, which has been studied since long, namely
with trapped ions, If you have a single ion in an ion trap--
an ion trapping is pursued here at MIT and [INAUDIBLE] group--
you have just a single object completely isolated.
And in form of the aluminum ion, this
has just been demonstrated to be the most accurate atomic clock
in the world, with 10 to the minus 17 accuracy.
So anyway, with optical lattices, avoiding
spontaneous emission using metric wavelengths,
we can no engineer with neutral atoms what has been available
with trapped ions, but we can simultaneously
have 10,000 copies, and look at 10,000 atoms
which are all identical copies, identical systems
of each other.
So you see already from that example
that there will be intellectual overlap and synergy
between talking about neutral atoms in optical lattices,
and talking about trapped ions and how they are cooled
and how they are manipulated.
And we talk about trapped ions at the end of the course,
sideband cooling of trapped ions, which is week 12.