Entanglement can help in classical communication

Mar 30, 2011 By Miranda Marquit feature

(PhysOrg.com) -- When most of us think of entanglement, our minds jump immediately to quantum communication. "Entanglement has become very well known and useful in quantum communication," Robert Prevedel tells PhysOrg.com. Prevedel, a scientist at the Institute for Quantum Computing at the University of Waterloo in Ontario, Canada, believes that entanglement can be used in classical communication as well.

“We have found that in certain situations you can use to transmit classical information with higher success when using classical channels that are noisy than you could do without.” says Prevedel. "This is a novel use for entanglement which seems to have been overlooked until recently."

A team of scientists at Waterloo, including Prevedel, Lu, Matthews, Kaltenbaek and Resch, demonstrated that that it is possible to benefit from entanglement in some classical communication channels. Their work can be found in Physical Review Letters: “Entanglement-Enhanced Classical Communication Over a Noisy Classical Channel.”

“One of the reasons that entanglement hasn’t been thought to be useful for classical communication is that it has been shown to not increase the capacity of a classical channel, which is the ultimate maximum rate of reliable communication” Prevedel explains. “What entanglement can do, though, is reduce the error probability when sending a message with a fixed number of uses of a noisy classical channel.”

Prevedel says that the protocol used is fairly simple. “Our demonstration included only two entangled particles and a straightforward classical channel. Entangled photons show nonclassical correlations,. Whenever I do a measurement on one of the photons, I will get a similar result for the same measurement performed on the other photon.”

“Sometimes a classical communication channel gets jumbled,” Prevedel explains. “We wanted to see if entanglement could be used to more successfully send information across such a noisy channel. With our simple protocol, and by using entanglement, we found that you can improve the success probability from 83% to 90%. That’s fairly significant.”

For now, the protocol only works on a very particular type of channel. “The situation we started with is very specific,” Prevedel points out. “We looked for the channel that would offer us the largest increase in success probability possible. Also, we knew that using entanglement in this manner won’t work with every type of classical communication channel.”

So far, the work done by the Waterloo team doesn’t offer immediate applications for communications. “Our results are more important from a fundamental point of view,” Prevedel says. “From a fundamental point of view, this is big news.”

Going forward, Prevedel hopes that he and his colleagues can learn more about the benefits that entanglement can have for classical communication. “We want to figure out which classical channels will benefit from it [entanglement], and which will not. We also want to see if there is a way to generalize our findings.” Additionally, the group is hoping that they can adapt what they learned to multi-party conversations. “It might be possible to find scenarios in which entanglement could help in three party or four party conversations – moving beyond two party communication.”

Overall, though, Prevedel and his colleagues are excited about the new prospects for combining classical communication with entanglement. “We have shown that entanglement can help in classical communication, a situation where people thought it was useless. Hopefully, our work will spark interest in this research direction, and we can begin to see some applications in the future.”

Explore further: Serial time-encoded amplified microscopy for ultrafast imaging based on multi-wavelength laser

More information: R. Prevedel, Y. Lu, W. Matthews, R. Kaltenbaek, and K.J. Resch, “Entanglement-Enhanced Classical Communication Over a Noisy Classical Channel,” Physical Review Letters (2011). Available online: link.aps.org/doi/10.1103/PhysRevLett.106.110505

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TabulaMentis
not rated yet Mar 30, 2011
The first area that comes to mind where entanglement could possibly be used in classical communications would be direct wire, McCullough loop and multiplex alarm systems/devices/monitoring where fiber optic and/or infrared communications are available.
Mercury_01
3 / 5 (2) Mar 30, 2011
Alarm systems?? I guess when your only tool is a hammer...

Im more curious as to how this might relate to communications between systems consisting of more than one particle. The universe will open up for us if we can find and exploit quantum effects in the macro scale.
TabulaMentis
not rated yet Mar 30, 2011
@Mercury:
Why don't you elaborate more on what you are talking about? You know, be more specific in how the theory can be applied down to the real word, instead of universal scales!
aphelion_anomaly
5 / 5 (1) Mar 30, 2011
Im sure many people share my desire to find a method of making measurable changes to an entangled set of particles that could be deciphered as binary or modulated information. The rate at which data could be transferred would not be as critical as the amount of time saved during transmission when considering deep space applications. If we could establish real time, or near real time interaction with probes regardless of distance we could drastically expand our options for extraterrestrial experimentation.
aphelion_anomaly
not rated yet Mar 30, 2011
I guess that goes without saying. More to the point; the impact of this method on traditional communication could help to better utilize the frequency bands that we already have at our disposal. I am curious whether the additional complexity to transceivers would negatively impact the bandwidth or response time. Seven percent is a good start, but getting that amount of improvement reliably (or better) on a majority of available bands would be necessary to justify the additional cost of manufacturing.
Mercury_01
3 / 5 (1) Mar 31, 2011
@Mercury:
Why don't you elaborate more on what you are talking about? You know, be more specific in how the theory can be applied down to the real word, instead of universal scales!


I think its obvious what Im talking about, and I didn't say anything about "universal scales", whatever that is. I'm referring to the world- changing repercussions there could be if we were to discover an exploitable level of quantum coherence within matter on the macro scale. There isn't enough room on this page to even begin listing the possible applications. It would make the internet look like two tin cans on a string. Coupled with quantum computing, nanotechnology, and neuro- technological integration, we would be like gods.

TabulaMentis
not rated yet Mar 31, 2011
@Mercury:
Instead of using classical entanglement to accomplish the cutting edge ideas to propose, then why not just use quantum entanglement instead. I was thinking more of today, now tech, not futuristic tech that may not be available for decades.
Mercury_01
5 / 5 (1) Mar 31, 2011
Im clearly being trolled. Please educate yourself before trying to get into discussions here. This is a website geared toward scientists.
holoman
not rated yet Mar 31, 2011
Using optical 3D molecular disk storage as an encryption and
entangled communication device was proposed by colossal storage
many years ago.
TabulaMentis
not rated yet Mar 31, 2011
Im clearly being trolled. Please educate yourself before trying to get into discussions here. This is a website geared toward scientists.
You appear to be confusing classic entanglement with quantum entanglement from the way you are talking. The article stated that they did not know how this idea/discovery could be applied to the real world of today.
TabulaMentis
not rated yet Mar 31, 2011
Coupled with quantum computing, nanotechnology, and neuro- technological integration, we would be like gods.
What you stated is not macro scales, it is micro!
Mercury_01
3 / 5 (2) Mar 31, 2011
Coupled with quantum computing, nanotechnology, and neuro- technological integration, we would be like gods.
What you stated is not macro scales, it is micro!


These are totally different technologies. Go troll somewhere else..
TabulaMentis
not rated yet Apr 01, 2011
@Mercury 01:
Read your comments and see who is trolling!
EWH
not rated yet Apr 16, 2011
Alarm systems?? I guess when your only tool is a hammer...

Im more curious as to how this might relate to communications between systems consisting of more than one particle. The universe will open up for us if we can find and exploit quantum effects in the macro scale.


Perhaps it's not quite what you meant, but superconductors are macroscopic quantum systems. All the electrons in a super-current behave like one giant particle, often thousands of meters long in a SC magnet coil. See Carver Mead's Collective Electrodynamics for details.

Also, classical equivalents of entanglement for encoding signals have been in use since at least the '40s - pairs of phonograph records of noise, convolved at one end of a phone conversation and deconvolved at the other. One-time pads are much older, newer systems use pseudorandom generators with shared seeds or sequences of seeds which allow effectively stretching the use of one-time pads.