Register to reply

Optical density of man atomic ensemble and linewidth

Share this thread:
Niles
#1
Nov18-12, 06:49 AM
P: 1,863
Hi

I've been thinking about something for a while now. If I take a two-level atom, completely at rest, then I can probe it with a quasi-resonant laser. The absorption of the atom is a nice Lorentzian, nothing fancy here.

However, now say I take 1011-1012 atoms. The specific number doesn't matter, all I am trying to do is to probe the system in a regime where the optical density has increased very much. For the sake of clarity I assume the atoms to be completely independent and at rest. No collisions/dephasing/... occur between them.

If I now probe this system, will I still see an absorption Lorentzian with the same FWHM as in the single-atom case? Or will the transition be broadened somehow?

The reason why I believe it should be broadening is because I keep thinking about, e.g., my table (or any other macroscopic object, a pencil, calculator, ...). It has an optical depth that is very large, so the absorption profile is also extremely broad. I was wondering if the same holds for an independent atomic ensemble.

I've been trying to look at the Optical Bloch Equations to see if such a behavior could occur, but it is not immediately clear that it is so. Is my analogy wrong?

Best,
Niles.
Phys.Org News Partner Physics news on Phys.org
Interfaces within materials can be patterned as a means of controlling the properties of composites
A new, tunable device for spintronics
Researchers study gallium to design adjustable electronic components

Register to reply

Related Discussions
Atomic Physics: Optical molasses Advanced Physics Homework 1
Microcanonical ensemble, density operator Quantum Physics 6
Spatial linewidth and density matrix Quantum Physics 0
Optical Spectroscopy and Atomic Structure Introductory Physics Homework 1
Finding the density matrix of an ensemble Quantum Physics 6