Register to reply

What's the physical interpretation of ρ for dipole forbidden channel?

Share this thread:
zhdx
#1
Sep27-13, 09:23 PM
P: 4
Consider we have a [itex]\Lambda[/itex] type three level system, the one upper level is denoted by 3, and the two lower levels are denoted by 1 and 2. Assuming that the transitions between 1[itex]\leftrightarrow[/itex]3 and 2[itex]\leftrightarrow[/itex]3 are dipole alowed, while the transition between two lower states 1 and 2 is dipole forbidden. As we know the real and imaginary part of ρ31 describe the dispersion and absorption of the external light in 1[itex]\leftrightarrow[/itex]3 channel. But what does the ρ12 mean?
Phys.Org News Partner Physics news on Phys.org
Technique simplifies the creation of high-tech crystals
Working group explores the 'frustration' of spin glasses
New analysis of oxide glass structures could guide the forecasting of melt formation in planetary interiors
M Quack
#2
Sep28-13, 04:26 AM
P: 660
The same thing.

Dipole-forbidden means that the electric dipole moment vanishes. Higher order multipole transitions (E.g. quadrupole) can still occur, but the matrix elements and thus the transition probabilities are much lower. Therefore the electric dipole is usually very dominant, and if the dipole is allowed, then all other transitions can be neglected. The net effect is that the 1-2 transitions are very weak (but still not completely forbidden)= the 2 state has a very long lifetime.
zhdx
#3
Sep28-13, 07:17 AM
P: 4
Quote Quote by M Quack View Post
The net effect is that the 1-2 transitions are very weak (but still not completely forbidden)= the 2 state has a very long lifetime.
Thanks!
Does the ρ12 has relation to the population distributions? Say consider two cases:
Case 1: ρ11=0.9, ρ22=0.1
Case 2: ρ11=0.1, ρ22=0.2
What I've found is that the ρ12 in Case 2 is much less than in Case 1. (I've add a dephasing constant γ2d for level 2 compared to level 1.)


Register to reply

Related Discussions
Dipole excitation response function - physical interpretation High Energy, Nuclear, Particle Physics 3
Physical Interpretation of Spin Quantum Physics 5
Physical interpretation of equations General Physics 1
Physical interpretation of Parity? High Energy, Nuclear, Particle Physics 35
Help with a physical interpretation General Physics 0