Physicists mimic quantum entanglement with laser pointer to double data speeds

October 28, 2015
Physicists mimic quantum entanglement with laser pointer to double data speeds
The shape and polarization of a conventional laser beam from a laser pointer mimics quantum entanglement when the laser beam has a polarization dependent shape. This can be used to encode twice as many bits of information as when the laser beam is "separable." Credit: Giovanni Milione

In a classic eureka moment, a team of physicists led by The City College of New York and including Herriot-Watt University and Corning Incorporated is showing how beams from ordinary laser pointers mimic quantum entanglement with the potential of doubling the data speed of laser communication.

Quantum entanglement is a phrase more likely to be heard on popular sci-fi television shows such as "Fringe" and "Doctor Who." Described by Albert Einstein as "spooky action at a distance," when two quantum things are entangled, if one is 'touched' the other will 'feel it,' even if separated by a great distance.

"At the heart of quantum entanglement is 'nonseparability' - two entangled things are described by an unfactorizable equation," said City College PhD student Giovanni Milione. "Interestingly, a conventional (a pointer)'s shape and polarization can also be nonseparable."

To make the laser beam's shape and polarization nonseparable, the researchers transformed it into what Milione refers to as a vector beam - a polarization dependent shape. Then using off-the-shelf components to 'touch' only its , they showed it could be encoded as two bits of information. Surprisingly, this was twice as much information that could be encoded as when the laser beam was separable.

"In principal, this could be used to double the data speed of ," said CCNY Distinguished Professor of Phyiscs Robert Alfano. ""While there's no 'spooky action at a distance,' it's amazing that aspects can be mimicked by something that simple."

An article on the experiment appears in the latest issue of the journal "Optics Letters"  and was supported in part by the Army Research Office.

Explore further: Researchers use novel polarization to increase data speeds

More information: Giovanni Milione et al. Using the nonseparability of vector beams to encode information for optical communication, Optics Letters (2015). DOI: 10.1364/OL.40.004887

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3.7 / 5 (3) Oct 29, 2015
Didn't understand a thing !!
3.7 / 5 (3) Oct 29, 2015
What does "'touch' the polarization mean"? How was it encoded? Polarization is not a one (or two) bit information after all! Also, an explanation of the nonseparability principle would help - it isn't clear what info was supposed to be separated. Providing links to trivial things like laser don't help; a link to the original aritcle, to concepts like nonseparability would.

What's more, I'm not sure in what way the information is doubled: if one laser beam is modified that's at least 1 bit of information encoded, so two laser beams could 'store' two bits in the same manner, if the combined beam also only stores two bits, there is no doubling at all!

The title is misleading too: most people will think of spooky action as a distance as the main distinguishing property of quantum entanglement, but there is no such thing here. Instead it seems like a trivial consequence of inference. If it's anything more than that, the article entirely failed to explain it.
Oct 29, 2015
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5 / 5 (2) Oct 29, 2015

-- click the link in the "more information" section at the bottom of the article and read the abstract of the paper.

The laser was treated as a vector beam and then the polarization was used to encode information as this is one quantum state that still has degrees of freedom in a vector beam. Using radial and azimuthal polarization two different bits of information can be encoded into the beam and separated back out 97% of the time.

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