Spontaneous emission and coherence

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SUMMARY

The discussion centers on the behavior of a linear superposition of quantum states, specifically the state ##\frac{1}{\sqrt{2}}(|g>+|e>)## involving ground state |g> and excited state |e>. It is established that after a time significantly longer than the excited state's lifetime, half of the initially prepared "atoms" will remain in the ground state |g>, while the remainder will decay into other levels. The negligible probability of returning to |g> from |e> confirms that the decay predominantly leads to other states, not back to |g>.

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  • Understanding of quantum superposition
  • Knowledge of atomic energy levels
  • Familiarity with spontaneous emission processes
  • Basic principles of quantum mechanics
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  • Study the implications of quantum superposition in multi-level systems
  • Research spontaneous emission and its role in quantum state decay
  • Explore the concept of coherence in quantum mechanics
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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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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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