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Thread: Interference using wavelength of an X factor

  1. #1
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    Interference using wavelength of an X factor

    So we all know the double-slit experiment resulting in an interference pattern: either constructive or destructive, depending on the phase of the photon.

    What if slit 1 receives photons of wavelength X and slit 2 receives photons of exactly wavelength X * 2.

    Will there be any interference on the screen, wavelengths being exact factors of each other?

  2. #2
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    you are mixing wave and particle language here
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  3. #3
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    I asked experienced lab engineers and they said:

    "Technically you can change their frequency slightly by heating and cooling them. They actually quite sensitive to temperature in terms of controlling the center of the band. The bandwidth is also very important. And solid-state laser quantum wells generally donít hold an ultra Narrow bandwidth. Sometimes it can be widest 2+ nanometers which is virtually useless for an interferometer. So getting the right frequency is only mildly important. Getting only and exactly that super narrow band output frequency is most key."


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  4. #4
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    The ultimate goal would to resonate (construct or destruct) tiny subatomic particles using the lasers we have today of much lower frequency.


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  5. #5
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    Quote Originally Posted by philippeb8 View Post
    The ultimate goal would to resonate (construct or destruct) tiny subatomic particles using the lasers we have today of much lower frequency.


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    philippeb8. When new particles form, they have mass/energy. That comes from the mass/energy of the creating photon. For photons with short wavelengths, and very high energy per photon, like a 2 million electron volt gamma ray, that's 2 Mev.....and it takes 1.022 Mev to make a positron/electron pair....leaving the 0. 978 Mev , or a little bit less as some of the energy goes into the kinetic energy of the pair of created leptons.
    Those are the lightest subatomic particles that have rest mass you can " construct". Heavier pairs, such as muon / antimuon, or pion/ antipion, also require more energetic gamma rays. Your interest in low frequency, and hence low energy photons from lasers of low frequency will not work to create subatomic particles with rest mass. You might find a photon creating an excited state of an atom while losing energy doing so, and then that excited state will decohere releasing a very low energy fluorescent photon, but you have created two new photons with zero rest mass each.
    That's why accelerators ramp up intersecting beams of electrons, protons, muons, to smash into targets showering particles in multiple directions of jets.
    pete

  6. #6
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    Quote Originally Posted by philippeb8 View Post
    So we all know the double-slit experiment resulting in an interference pattern: either constructive or destructive, depending on the phase of the photon.

    What if slit 1 receives photons of wavelength X and slit 2 receives photons of exactly wavelength X * 2.

    Will there be any interference on the screen, wavelengths being exact factors of each other?
    Unless the same wave/particle hits both slits, you won't get an interference pattern as all, even if the wavelengths match, because it's crucial to have the particles be in phase. Just moving the slits far enough apart (or somehow shielding them from each other) so that slit 1 only receives photons from source 1 while slit 2 only receives photons from source 2 will destroy the interference pattern, even if source 1 and 2 have the same wavelength (let alone if they have different wavelengths). Heck, even with a single source, if you set up the experiment such that each photon can definitely be said to go through one slit or the other unambiguously, you'll lose the interference pattern.

    The interference is present specifically because a wave travels though both slits, and so can take different paths (with different lengths) to the same point on the detector, resulting in constructive or destructive interference.
    Conserve energy. Commute with the Hamiltonian.

  7. #7
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    Quote Originally Posted by Grey View Post
    Heck, even with a single source, if you set up the experiment such that each photon can definitely be said to go through one slit or the other unambiguously, you'll lose the interference pattern.

    The interference is present specifically because a wave travels though both slits, and so can take different paths (with different lengths) to the same point on the detector, resulting in constructive or destructive interference.
    Ok thanks!


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