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April 08, 2005

Class review — 4/7

Hey Class,

Remember that problem 2 is due on Tuesday.

There will be reading material for next class and pre-flights up by tomorrow afternoon.

A few questions came up in class; the answers follow. First: the scattered light for a single, two-level atom in free-space is always exactly at the frequency of the driving field (the spectrum is a delta-function). Second: one should not employ an intermediate state when arguing this (like I did, when I said that the atom was in the excited state). Hmmm... it seems as if there were more questions. Comment on this blog entry if you can think of them! I still haven't figured out what's going on with the entropy of the universe.


Yesterday we spoke about:
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  1. We learned about Mollow's transformation, which tells us that an EM field in a coherent state interacting with an atom is equivalent to a classical field plus the quantum vacuum interacting with the atom.

  2. We talked about "scattering" and the Optical Bloch Equations (OBEs). Thi is just a density matrix description of light scattering (laser incident on an atom and a detector measuring scattered light). We define the fluorescence rate as the decay rate times the excited state population. The fluorescence rate has a Lorentzian dependence on detuning, and saturates at high driving intensities (there are many ways of understanding that).

  3. We saw spontaneous Raman scattering in the context of quantum jumps.

  4. We ended with a summary of what we know about light and atoms now, and the different pictures that we have.

Cheers,

Brian

Posted by Brian at April 8, 2005 10:27 AM

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