M1intro2.txt

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Welcome to the course on atomic and optical physics.
We now start with Module 1.
The study of resonances has been a watershed in physics,
because studying resonances allows for precise measurement.
It is an unwritten rule in physics
that if you want to measure something precisely,
you have to find a way to express
the quantity of interest, in terms of a frequency
measurement, and then precisely measure
the frequency spectroscopically for resonance.
Therefore, it is very appropriate
that the theme of Module 1 of this course
is the theme of resonance, of resonance physics.
We look at resonance in the simplest physical system
of two levels, realized by spin 1/2 in a magnetic field.
However, we look at the system from both
a classical and a quantum perspective.
A two level system can be fully captured by classical equations
describing the precession of a classical magnetic moment
in a magnetic field.
And I know from my experience that every student is surprised
when he or she hears that concepts
like rapid adiabatic passage, Rabi frequencies, spin flips,
can be fully captured by classical equations.
And this expresses a central aspect of this course,
that we try to shape our intuition for physics
by looking at the physics from different perspectives,
and understanding which description
is most appropriate for which phenomenon.