Enhancing Spontaneous emission in a vacuum standing wave

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Discussion Overview

The discussion revolves around the enhancement of spontaneous emission of an atom positioned in a vacuum standing wave field within a cavity. Participants explore the implications of placing the atom at nodes versus anti-nodes of the standing wave, examining the conditions under which spontaneous emission is enhanced or suppressed.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant asserts that spontaneous emission is enhanced when an atom is at a node of the vacuum standing wave field, questioning why this occurs since nodes have zero intensity.
  • Another participant counters that to enhance spontaneous emission via the Purcell effect, emitters should be placed at the anti-node, suggesting that nodes inhibit emission.
  • A third participant raises a question about the type of field (electric or magnetic) relevant to the discussion, emphasizing the importance of coupling strength between the atom and the field.
  • One participant expresses doubt about their professor's materials, indicating that their research supports the idea that enhancement occurs at anti-nodes.
  • A later reply references a paper that claims emission is suppressed at anti-nodes under specific conditions, suggesting a complexity in the relationship between position and emission characteristics.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the optimal positioning of the atom for enhancing spontaneous emission, with competing views on the roles of nodes and anti-nodes. The discussion remains unresolved as no consensus is reached.

Contextual Notes

Participants reference different effects and conditions, indicating that the discussion may depend on specific setups or interpretations of the Purcell effect and other phenomena. The implications of coupling types and field characteristics are also noted as potentially significant but not fully explored.

SchroedingersLion
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Hi,

it is well known that spontaneous emission of an atom can be enhanced, if the atom sits at a node of the vacuum standing wave field in a cavity.

My question is, why is it the node? At a node of a standing wave, there is zero intensity, so there should be no interaction between the atom and the virtual photons there. Shouldn't it be the anti-node?

Regards
 
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Is that so? If you want to enhance spontaneous emission by means of the Purcell effect, you always try to place your emitter at the antinode of the cavity field. You try to place it at the node in order to inhibit spontaneous emission.

Do you have a reference for that claim? Maybe they do not discuss the Purcell effect, but some other effect?
 
What type of field? E or B?
You want to place your atom where the coupling (g) between the relevant field (which for an atom would usually be the B field) and the relevant transition is the strongest.

This is a good example of a situation which is easier to understand when dealing with qubits coupled to a transmission line resonator (lambda/2) since you can use normal circuit theory. If the qubit is capacitively coupled to the resonator you want to place it at either end where the voltage is maximum; if the coupling is inductive in the centre where the current has a max.
Note that the physics is absolutely identical to the situation where you have an atom in a 3D cavity.
 
Hi,

maybe my professor did a mistake on his sheets... after paper research, I only found implications of the enhancement for the anti nodes. I thought it made no sense^^
 

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