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Hyper-Entangled Photons — 'Superdense' Coding Gets Denser

Posted by ScuttleMonkey on from the so-tangling-is-a-good-thing dept.

ScienceDaily is reporting that researchers at the University of Illinois have broken the record for most information sent via a single photon using the direction of "wiggling" and "twisting" a pair of entangled photons. "Using linear elements, however, the standard protocol is fundamentally limited to convey only one of three messages, or 1.58 bits. The new experiment surpasses that threshold by employing pairs of photons entangled in more ways than one (hyper-entangled). As a result, additional information can be sent and correctly decoded to achieve the full power of dense coding."

5 of 72 comments (clear)

  1. Re:This should help by unchiujar · · Score: 2, Informative

    Do not click.
    Link contains shock site.

    --
    Shakespeare poems - infinite monkeys with infinite time.Computer tech support - a few trained ones working from 9 to 5.
  2. Re:superdense alright by blueg3 · · Score: 5, Informative

    They just mean that their objects can encode one of three states. The amount of information, in "bits", a state encodes is log2(number of possible states), and log2(3) ~= 1.58. By the same token, a single decimal digit stores 3.32 bits.

  3. ugh... by slew · · Score: 4, Informative

    First off, isn't this rehashed news from 2005?

    Secondly, why did they have to change the word polarization to "wiggling"? As if lay people didn't know the word polarized from experience with their sunglasses.

    Perhaps I'll concede that calling orbital angular momentum to "twisting" may be a reasonable twisting of the terminology, although in earlier papers they refer to "spiraling" or "cork-screw" which seems like a much better scientific-speak-transliteration to me...

  4. Isn't the information per photon arbitrary? by gregor-e · · Score: 2, Informative

    Seems to me that angle isn't quantized. Therefore, the amount of information that one can encode on a single photon is only limited by our ability to encode and decode the angle at which a photon is traveling. Given the ability to measure the angle of a photon down to, oh, something on the order of 10e-34 radians or so, one should have no problem transmitting multiple yottabytes on a single photon.

    1. Re:Isn't the information per photon arbitrary? by QuantumFTL · · Score: 2, Informative

      Given the ability to measure the angle of a photon down to, oh, something on the order of 10e-34 radians or so, one should have no problem transmitting multiple yottabytes on a single photon.
      Looks like someone didn't take their Quantum class before posting! Shame on you!

      Before a photon's polarization is measured, it exists as a wavefunction expressable as a linear combination of eigenstates for a given polarization operator. After being measured, its state is only one eigenstate of the particular polarization operator used (what laymen might call "parallel" or "perpendicular"). There is no way to measure the "exact" polarization of a photon - indeed quantum theory says it does not have one, save for the exact moment of being measured (when it is "collapsed" or whatever you wish to call it) when it takes on a single eigenstate, defined by the measuring apparatus.

      There are other operators with potentially infinite numbers of eigenstates, and provided you could find one with a large number of eigenstates at attainable energies, you might be able to do as you suggest. But as for polarization, sorry it's fundamentally limited.