Stimulated Emission has no sufficient proof?by TMSxPhyFor Tags: emission, proof, stimulated, sufficient 

#1
Jan1412, 06:43 AM

P: 53

Hi All
I was surfing Internet trying to understand why most books i read simply considers that the stimulated photon emission has same properties as the stimulating photon, and treats this simply as an "take as it is". For my surprise, i found this article: http://www.sjsu.edu/faculty/watkins/stimem.htm I liked it becuase it explains how Einstein thought about this in his original paper, but It states that actually there is no sufficiently satisfactory proof for that even in quantum mechanics!!: 



#2
Jan1412, 03:42 PM

Sci Advisor
P: 1,563

In "fundamental" treatments of stimulated emission one rather goes the other way round. You start by dividing the emission into distinguishable and indistinguishable parts and then show that the indistinguishable part can create a stimulated enhancement. Basically one can backtrack stimulated emission to the spin statistics theorem and the properties of bosons as opposed to fermions. In short there is a significant enhancement for processes which create indistinguishable bosons like stimulated emission or bosonic final state stimulation. This is basically a consequence of interference of indistinguishable probability amplitudes. 



#3
Jan1412, 04:14 PM

P: 53

Yes I agree with you, that sentence seems to be very suspicious.




#4
Jan1512, 06:59 AM

Sci Advisor
P: 1,563

Stimulated Emission has no sufficient proof?
The reason why that topic is not covered in too many books lies in my opinion in the fact that stimulated emission can be explained pretty well classically in full analogy to a classical driven dipole and it is only spontaneous emission which needs a quantum treatment.
Therefore there are not many who really bother with setting up a complete first principle quantum description of stimulated emission. For suggested reading, many books on quantum optics will cover this topic. "Optical coherence and quantum optics" by Mandel and Wolf is the bible in this field. However, I must warn you that although it is well written, it takes a lot of time to read and digest it. For a more pedagogical approach to the problem, you might start by reading about the HongOuMandel effect (the original citation is C. K. Hong, Z. Y. Ou, and L. Mandel, Phys. Rev. Lett. 59, 2044 (1987), but you will find many easier descriptions using google or books on quantum optics) or the Hanbury BrownTwiss effect (R. HanburyBrown and R. W. Twiss, Nature 177, 27 (1956), but again there are summarized descriptions all over the web). These give a good first impression of the link between statistical properties and indistinguishability. A thorough theoretical description of these links has been given by Glauber, for example in: R. J. Glauber, in Quantum Optics and Electronics (Les Houches Lectures), p.63, edited by C. deWitt, A. Blandin, and C. CohenTannoudji (Gordon and Breach, New York, 1965), but also here understanding takes some time. For experimental tests you can check F. W. Sun et al., "Stimulated Emission as a Result of Multiphoton Interference", Phys. Rev. Lett. 99, 043601 (2007). Maybe following this paper and the references therein is an easier way to get the topic. A free version under a similar name is available on the ArXiv in case you do not have access to PRL. MAybe one of these approaches helps you. 



#5
Jan1512, 10:24 AM

P: 53

Thank you for the detailed answer :)
I checked Hong–Ou–Mandel effect on wikipedia and "Stimulated emission of two photons in parametric ampliﬁcation and its interpretation as multiphoton interference" paper from arXiv, now it's much clearer how interference of indistinguishable photons plays it's game (it's nice to understand things deeper), even so I need to know more QM to understand the math of that paper. anyway, just wanted to point, that even in that paper the authors said at the beginning that: 



#6
Jan1512, 11:46 AM

Sci Advisor
P: 8,007

It may also help to look at Rabi oscillations, which involves stimulated emission, and its treatment with the quantized electromegnetic field in the JaynesCummings model.
http://physics.schooltool.nl/quantumoptics/rabi.php http://www.stanford.edu/~rsasaki/AP387/chap6 The relationship between treating the electromagnetic field classically and quantum mechanically is also discussed in http://www.amazon.com/IntroductoryQ.../dp/052152735X, section 4.3, "Interaction of an atom with a quantized field". On p83, they write "(n=0) ... This is spontaneous emission and it has no semiclassical counterpart. If n>0, the emission of an additional photon is called stimulated emission.". (A free account will allow you to view search results.) 



#7
Jan1612, 04:37 AM

Sci Advisor
P: 1,563





#8
Jan1612, 12:56 PM

PF Gold
P: 779

I wouldn't rely on Wikipedia for things. Even though when you read an article and you see it well explained, doesn't make it true. Anyone could have written that, and if you're not well knowledged in the area you won't see errors if there are any.




#9
Jan1612, 06:44 PM

P: 367

Again, this is the guy critiquing the sophistication of quantum mechanics..... 


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