Researchers Demonstrate Quantum Teleportation and Memory in Tandem

Jan 30, 2008 By Laura Mgrdichian feature

In research that may be a key step toward real-life quantum communication—the transmission of information using atoms, photons, or other quantum objects—researchers created an experiment in which a quantum bit of information is transported across a distance of seven meters and briefly stored in memory. This is the first time that both quantum memory and teleportation, as the information transfer is known, have been demonstrated in a single experiment.

The experiment was performed by scientists from the University of Heidelberg in Germany, the University of Science and Technology of China, and the Atomic Institute of the Austrian Universities in Austria. The work was led by Prof. Jian-Wei Pan, a physicist at the University of Heidelberg.

A quantum bit, or qubit, is the most basic unit of quantum information. It takes the form of a particular configuration, or “state,” of an atom or photon. Unlike a traditional computer bit, the most basic piece of information a computer can store, qubits represent the superposition of “0” and “1,” rather than either a 0 or 1. Additonally, a qubit cannot be copied in the traditional sense. It can only be transferred, without leaving any trace of the original.

Quantum teleportation is the way to transfer an unknown quantum state to a distant location without getting any information about the state in the course of this transfer. When a qubit is teleported across a distance, the process is remarkable in that the sending and receiving qubits are not physically connected in any way, and do not “know” of each other's existence. But through a quantum phenomenon called entanglement, one qubit is nonetheless able to assume the quantum state of another without physically interacting with it.

In the present research, described in the January 20 online edition of Nature Physics, an unknown quantum state of a photonic qubit is transferred into quantum memory via teleportation and is stored by two clusters of rubidium atoms. Each cluster contains approximately one million atoms, collected by a magneto-optical trap. The teleported photonic qubit can be stored in memory and read out up to eight microseconds (millionths of a second) before the state is lost.

“Such an interface to map the quantum states of photons onto the quantum states of matter, and to retrieve them without destroying the quantum character of the stored information, is an essential part of future quantum technologies,” said Pan to PhysOrg.com. “It represents an important step towards efficient and scalable connection of quantum networks.”

The quantum states carried by the photonic qubits are encoded in the photons' polarization, or the alignment of the photons' emitted electric fields. Each rubidium cluster encodes the information as a collective spin state over all of the electrons in the cluster. Like other unchangeable properties like mass and charge, spin, or angular momentum, is an intrinsic characteristic of an electron.

First, the research group entangled the polarization state of the photons and the spin state of the atom clusters. This entanglement is then exploited to teleport the unknown state of a single photonic qubit onto an atomic qubit seven meters away. This is done by taking a simultaneous measurement of the entangled photons and the photon to be teleported. Taking that measurement entangles the two photons and projects the second photon's state onto the atom clusters.

This setup does have some serious problems. The quantum memory duration is very short and the probability that the photon will be teleported is low. Therefore, the researchers say that “significant improvements” need to be made before the scheme could be used in practical applications.

Citation: Yu-Ao Chen, Shuai Chen, Zhen-Sheng Yuan, Bo Zhao, Chih-Sung Chuu, Jörg Schmiedmayer & Jian-Wei Pan Nature Physics advance online publication, 20 January 2008 (DOI:10.1038/nphys832).

Copyright 2008 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

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User comments : 14

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earls
3.4 / 5 (5) Jan 30, 2008
I personally think "teleportation" is being thrown around a bit casually.
gopher65
3.5 / 5 (4) Jan 30, 2008
No kidding earls! There needs to be some distinction between scifi stuff and the real world.
earls
2.3 / 5 (3) Jan 30, 2008
gopher65,

"Teleportation is the movement of objects or elementary particles from one place to another, more or less instantaneously, without traveling through space."

Especially when "as defined as" above and the truth about the experiment(s) has been shoved down our throats by the "Sceince" nazis. I would appreciate it in the future if the term "teleportation" was restricted to feature(s) of instantaneous information transfer and not to the classical transportation of information between particles that share a common ... entanglement.

Please physorg/laura, please?
holoman
1.8 / 5 (5) Jan 30, 2008
Colossal Storage published papers many years ago
about this technology using their patents.

http://www.coloss...gled.htm

Now it looks like someone has proof of concept.

earls
3.4 / 5 (5) Jan 30, 2008
Regardless, with all apologies, Colossal Storage ain't deliver shit but animated gifs, so, enjoy your patents. When you can profess a true understanding of the "forces" at work and deliver a fully functional product, ALERT THE INTERNETS.
brant
1 / 5 (3) Jan 30, 2008
"But through a quantum phenomenon called entanglement, one qubit is nonetheless able to assume the quantum state of another without physically interacting with it."

Without physically interacting with it???
Are they missing something here, like an aether...

Maybe there are waves that have not been discovered yet. But wait, we know thats wrong so why look for it?

I'd rather have entanglement Faeries that carry the state of the qubit than "no physical interaction"...
earls
2 / 5 (4) Jan 30, 2008
With all due respect brant, "try again."
Hossin08
2.3 / 5 (3) Jan 31, 2008
Shouldn't you kids learn English before you wander into the grown-up pool?
Fredsie
1 / 5 (2) Jan 31, 2008
"Quantum teleportation is the way to transfer an unknown quantum state to a distant location without getting any information about the state in the course of this transfer." Forgive my ignorance, but if the quantum state is "unknown" before and after the transfer, how do you know that the result corresponds in state to the starting point?
HeRoze
3.5 / 5 (2) Jan 31, 2008
Fredsie - here is an old article that may help explain this. It just boggles my mind, but you may stand a chance.
http://www.resear...rtation/
holoman
1 / 5 (3) Jan 31, 2008
Earls, you sound envious. How do you know
what and where Colossal is with their technology ? Do you have proof otherwise ?

Maybe they have already produced a prototype that is in the hands of a few select companies evaluating under secret agreement.

Its unfortunate that this board always has to have a few hateful agitators posting negative garbage to get attention.
earls
3 / 5 (4) Jan 31, 2008
I AM envious. More like "Do THEY have proof otherwise?"

"Maybe they have already produced a prototype that is in the hands of a few select companies evaluating under secret agreement."

Of course! NO DOUBT! While accredited academic scientists toil, study, and experiment with a brand new facet of the Universe, COLOSSAL STORAGE has SOMEHOW leap frogged EVERYONE IN THE WORLD and created a novel, earth shattering method of communication and storage.

No, what is unfortunate is that you feel the need to advertise your/their vaporware in the comments section of any entanglement related news article when there's nothing to show in the first place!

Not to mention, it has been explained to you multiple times that entanglement and teleportation DO NOT work the way you (and Colossal Storage) assume.

But hey, whatever. Label me a hater, agitator, and negativator. Above all, I am a DOUBTER and a SKEPTIC of novel and ground breaking technologies that come with ZERO PROOF OF CONCEPT besides flash animations from YET ANOTHER patent troll.

Post all the non-sense you want, I'm NOT BELIEVING until I'm SEEING. Keep me updated.
Ashibayai
1.5 / 5 (2) Feb 01, 2008
Well, it's unlikely that they would have such abilities without releasing the information that they had found a way to really manipulate it seeing as it would be so profound a discovery that it's in their best interest to be public about it.

That being said, pointing out existing patents isn't exactly a horrible deed.
superhuman
not rated yet Feb 27, 2008
Somehow I'm much more willing to accept transactional interpretation of QM then Copenhagean one.

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