Spontaneous emission and coherence

In summary, spontaneous emission refers to the process by which an excited atom or molecule emits a photon and transitions to a lower energy state without external influence. This phenomenon is inherently random, leading to a lack of phase coherence among the emitted photons. Coherence, on the other hand, describes the correlation between the phases of waves, which is crucial for the formation of structured light fields, such as lasers. The interplay between spontaneous emission and coherence is essential in understanding light-matter interactions, influencing technologies like lasers and quantum optics, where controlled emission and coherence are desired for practical applications.
  • #1
kelly0303
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Assume I prepare a linear superposition ##\frac{1}{\sqrt{2}}(|g>+|e>)## between a ground and excited level for a large number of "atoms" (it can by any multilevel system, not necessarily an atom). We can assume that the lifetime of the excited level is long enough to allow us to create this superposition, but it is not infinite. Assume also that the excited state can decay to many other levels, beside ##|g>##, such that the probability of ##|e>## decaying back to ##|g>## is negligible for the purpose of this question. If I wait for a time much longer than the lifetime of the excited state (the ground state is stable), will I find half of my initially prepared "atoms" in ##|g>## and the other spread among the other levels, or will all the "atoms" decay to the other levels? Thank you!
 
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  • #2
kelly0303 said:
will I find half of my initially prepared "atoms" in |g>
Yes. What made you think that it might not be the case?
 

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