Could Quantum Dots Between Optic Fibers Create Photon Interference?

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Discussion Overview

The discussion revolves around the potential for photon interference when a quantum dot is placed between two optic fibers, particularly when the fibers converge at a beamsplitter. Participants explore the theoretical implications of photon emission from the quantum dot and inquire about any existing experimental evidence for such setups.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes a quantum dot emitting photons in all directions, questioning whether interference occurs if the photon is not observed outside the fibers.
  • Another participant seeks clarification on the nature of the photon emission, asking if it involves a random direction or a spherical wavefront.
  • A participant connects the discussion to the Mott problem, suggesting that interference should occur after the beamsplitter, contingent on the experimental setup.
  • Concerns are raised about the details of the experiment, including the excitation mechanism of the quantum dot and the geometry of the setup.
  • One participant questions the choice of quantum dots, suggesting that single ions in a Paul trap may offer better symmetry properties for such experiments.
  • A reference is provided to a related experiment involving single atoms and interference patterns, noting that similar experiments with fibers may face challenges due to coupling efficiency.
  • A participant expresses interest in the referenced experiment and inquires about the potential suppression of radiation in a cavity setup.

Areas of Agreement / Disagreement

Participants express various viewpoints on the feasibility and implications of the proposed experiment, with no consensus reached on the specifics of the setup or the interpretation of results.

Contextual Notes

Participants note limitations regarding the geometry of the quantum dot and the emission characteristics, as well as the potential challenges in achieving effective coupling with single mode fibers.

Quant
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TL;DR
Is there interference from opposite directions of possible
propagation of a photon?
A quantum dot is placed in a line between two optic fibers
The dot can emit a photon in every direction which is unknown.

If the fibers are combined at a beamsplitter would there be interference if the photon
is not observed outside the fibers?

Do you know if somebody made such experiment?
Thanks anyone for considerations.
 
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Quant said:
The dot can emit a photon in every direction which is unknown.
By “in every direction which is unknown” do you mean the photon is prepared with some momentum is some direction, but the emission mechanism is such that that direction is random? Or do you mean that we have a spherical wavefront until some interaction happens?

If the latter, you will want to Google for “Mott problem” and work through its solutions first.
 
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Yes this is Mott problem but not with alpha particles but photons.
i know it for long time. I think that according to Mott decision the possibility
will travel tru both fibers and one must observe interference after the beam
splitter.
The question is has it been done experimentally?
This will confirm that the "wave function" of the photon is expanding sphere from
start to finish.
 
Quant said:
This will confirm that the "wave function" of the photon is expanding sphere from
start to finish.
Methinks the devil here is in the detail. Exactly what the experiment confirms will depend upon how you choose to set it up and then upon interpretation of the results. Can you flesh out the excitation of the dot, for instance, and the rest of the proposed geometry?
I was totally unaware of the Mott problem and therefore appreciate this line of inquiry!
 
hutchphd said:
Can you flesh out the excitation of the dot, for instance, and the rest of the proposed geometry?
I was totally unaware of the Mott problem and therefore appreciate this line of inquiry!
In QDs electron is excited by UV and then radiates. I am not aware in their geometry
but suppose that the radiation can be emitted at least to 150 degree which suffice
for the goal. What do you mean to depend on interpretation? This will not decide
between them but the shape of 'photon'.
 
Last edited:
Is there any specific reason why you choose quantum dots for this? At least self-organized QDs are usually lens-shaped and therefore inherently asymmetric. The symmetry properties are much better, e.g., for single ions in a Paul trap.

This is not exactly the geometry you mention, but I think this captures the spirit of what you are interested in:
https://www.nature.com/articles/35097017

J. Eschner et al., "Light interference from single atoms and their mirror images", Nature 413, 495 (2001). It is not on the ArXiv, but you might find free versions hosted by the authors on the internet. This is from Rainer Blatt's group and Ferdinand Schmidt-Kaler was the postdoc supervising the experiment. What Ferdinand did was to investigate the emission of the atom along opposing directions and to put a mirror in one of the directions, so that the light gets reflected and superposed with the beam going the other direction. One then finds an interference pattern when moving the mirror. This shows that there is interference between the beams going in two different directions. The emitter is a single barium ion. I do not think anyone did this using fibers as for single mode fibers the coupling efficiency is probably quite horrible.
 
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Cthugha said:
Is there any specific reason why you choose quantum dots for this? At least self-organized QDs are usually lens-shaped and therefore inherently asymmetric. The symmetry properties are much better, e.g., for single ions in a Paul trap.

This is not exactly the geometry you mention, but I think this captures the spirit of what you are interested in:
https://www.nature.com/articles/35097017

J. Eschner et al., "Light interference from single atoms and their mirror images", Nature 413, 495 (2001). It is not on the ArXiv, but you might find free versions hosted by the authors on the internet. This is from Rainer Blatt's group and Ferdinand Schmidt-Kaler was the postdoc supervising the experiment. What Ferdinand did was to investigate the emission of the atom along opposing directions and to put a mirror in one of the directions, so that the light gets reflected and superposed with the beam going the other direction. One then finds an interference pattern when moving the mirror. This shows that there is interference between the beams going in two different directions. The emitter is a single barium ion. I do not think anyone did this using fibers as for single mode fibers the coupling efficiency is probably quite horrible.
Thank you. This is it exactly. I didn't read it yet.
I suppose the radiation is suppressed as in cavity?
 

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