M3intro.txt

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Welcome to the third part of the course
on atomic and optical physics.
The first two parts on resonance and atoms
have prepared us for what can be regarded
as the central theme of atomic physics--
the interaction between atoms and light.
Light is introducing an enormous richness into the field
because light in the form of photons is a quantum object
and requires concepts of quantum field
theory for its description.
When atoms interact with the many modes
of the electromagnetic field, we also
have an open quantum system, which
is subject to dissipation and irreversibility.
These and other topics are presented in this module.
Depending on the atomic structure,
atoms can interact with light electrically or magnetically.
Atoms can exchange angular momentum with light.
And this is described by selection rules.
The light can be strong or weak.
The transition can be narrow or broad.
And this leads to very different dynamics of the atomic system.
The quantization of the electromagnetic field
provides us with the first principle description
of photons and spontaneous emission.
When spontaneously emitted photons
are captured in a cavity, there is no dissipation
and randomness.
And these and other examples will
be used to address misconceptions
about spontaneous emission.
Atoms, light, and electromagnetic fields
and their interactions are the building blocks
of quantum computers and many other interesting quantum
systems.
Atomic physicists continue to assemble and study such systems
to obtain a deeper understanding of the quantum world.  I hope you enjoy this module with me.