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Photon Storage

  1. Jul 6, 2007 #1
    Just a few questions for anyone. I am trying to buffer photons for a long delay quantum eraser.

    Is there anyway to convert one arm of a 4km LIGO interferometer into a high-fidelity photon buffer? If a beam is merely reflected once down the length of the tube, it is stored for ~13 µs with virtually no loss.

    This of course is if the recycling mirrors are removed. In the current configuration the Fabry-Perot interferometer keeps the photon reflecting back and forth inside the arm a number of times before letting it escape back to the beam splitter. It does this using a recycling mirror with low transmittance. Therefore, the number of times it reflects is totally random; it could make fifty trips or only one trip.

    BS___ Recycling Mirror___Mirror
    /------|==============||

    In an experiment I am simulating with java, I want to be able to selectively erase or destroy the "which-way" data in idler photons during specific time periods - bits composed of multiple photons. Therefore, it is necessary that every photon be stored for the same amount of time.

    To the point. Would it be possible to use the LIGO arm to store photons in a similar matter, except making the recycling mirror a full mirror? The input beam would have to enter to the left of the recycling mirror at very slight angle so that it will be reflected back and forth a number of times before exiting to the right. This way the storage time would be constant.

    ====================== .....****
    ...../\....../\....../\....../\................|
    ..../..\..../..\..../..\..../..\...............|
    .../....\../....\../....\../....\............4 km
    ../......\/......\/......\/......\.............|
    ./...===============...\............|
    /...................................\........****

    // (Sorry about the periods(.), I needed to use them for spacing)

    The LIGO tube is 4 ft. in diameter and the mirrors are 10 in. in diameter. Larger mirrors could be built to allow for more zigs and zags inside the arm; this would make the scheme more feasible. Mirrors with novel geometry could also be constructed to allow more elaborate/longer trips inside the tube, perhaps utilizing more than one plane of reflection. The reflection off the LIGO mirrors is so high (99.99%) that even after 1000 trips, ~82% of the photons are still with us. And of course the tube is a near perfect vacuum, so there is virtually no loss there.

    This is my question, would it be feasible? The goal would be to get something around a millisecond of storage (which is about what LIGO accomplishes on average), but with this scheme there is a consistent storage time instead of an average. This way we could store solitons of quantum data instead of highly dispersive wave packets that would quickly muddle together if one attempted to run a quantum eraser with multiple bits.

    Thank you for your time. If you have any questions, e-mail me at kpedersen1@gmail.com.
     
    Last edited: Jul 6, 2007
  2. jcsd
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