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Diamonds entaglement in 2011

  1. Feb 9, 2016 #1
    I decided to start a specific thread over this because I am interested in opinions of more expert members than me. In 2011. there was an experiment which entagled diamonds at room temperature. Here is the paper: https://www.researchgate.net/publication/51855622_Entangling_Macroscopic_Diamonds_at_Room_Temperature [Broken]

    Now I did some research here on forum about it and some members said that the result is an exaggeration. https://www.physicsforums.com/threads/a-classical-object-behaving-quantum.556018/

    This is the math behind it which apparently shows that the phonon didn't spread so much to cover the whole diamonds.

    1 fs (femtosecond) = 10-15s. Laser pulse duration = 100 fs Time between laser pulses = 350 fs. Speed of sound in diamond v ~ 12000 m/s. From this one easily can estimate how far a phonon can spread/propagate in 350 fs as dx = v*dt = 12000*350*10-15 = 4.2*10-8m = 4.2*10-5mm. Given the diamonds were each around 3mm in size, then if roughly cubic in shape, the fractional volume occupied by phonon at end of dual pulse run is of the order 4*pi/3*(4.2*10-5/3)3 ~ 10-14. So to say 'the diamonds' were in a state of superposition does indeed seem just a trifle exaggerated! The above assumes a classical spherical spreading pulse as 'phonon', but that is therefore probably a somewhat overestimate of volume occupied by excited material.

    Can anybody tell me is this accurate and did only parts the diamond got entagled? Thanks in advance
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Feb 14, 2016 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
  4. Feb 14, 2016 #3

    This article http://www.nature.com/news/entangled-diamonds-vibrate-together-1.9532 should answer your second question.

    "The researchers used a laser pulse to stimulate phonon vibrations in two crystals 3 millimetres wide and 15 centimetres apart. They say that each phonon involves the coherent vibration of about 10^16 atoms, corresponding to a region of the crystal about 0.05 millimetres wide and 0.25 millimetres long — large enough to see with the naked eye."
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