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Hyper-Entangled Photons — 'Superdense' Coding Gets Denser
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."
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.
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...