[dorkbotsea-blabber] teleporting

[Kevin Purcell]

The Nature paper is at

<http://arxiv.org/abs/quant-ph/0605095>

> Quantum teleportation is one of the main paradigms in quantum  
> information science. It is an important ingredient in distributed  
> quantum networks, and can also serve as an elementary operation in  
> quantum computers. In this paper we demonstrate for the first time  
> quantum teleportation between two objects of different nature: a  
> pulse of light and a material object. A quantum state encoded in a  
> mesoscopic light pulse is teleported onto an atomic ensemble  
> containing 10^12 Cesium atoms. The teleportation is performed at a  
> distance of 0.5m, and this distance can be increased limited  
> primarily by losses in the transmission of the light. The  
> teleportation is deterministic, with a fidelity of 0.58+-0.02 for  
> coherent states with a mean photon number of 20 and a fidelity of  
> 0.61+-0.02 for states with 5 photons - significantly higher than  
> any classical state transfer can possibly achieve. Quantum  
> teleportation between the carrier of information - light - and the  
> storage and processing medium - atoms - is a new step towards  
> distributed quantum networks.

The follow up paper (destined for Phys Rev A) is at

<http://arxiv.org/abs/quant-ph/0608133>

> We show how high fidelity quantum teleportation of light to atoms  
> can be achieved in the same setup as was used in the recent  
> experiment [J. Sherson et.al., quant-ph/0605095, accepted by  
> Nature], where such an inter-species quantum state transfer was  
> demonstrated for the first time. Our improved protocol takes  
> advantage of the rich multimode entangled structure of the state of  
> atoms and scattered light and requires simple post-processing of  
> homodyne detection signals and squeezed light in order to achieve  
> fidelities up to 90% (85%) for teleportation of coherent (qubit)  
> states under realistic experimental conditions. The remaining  
> limitation is due to atomic decoherence and light losses.

85% fidelity :-)

No, the Teleporter isn't just around the corner though it does make  
good copy for general new outlets. Why, because quantum teleportation  
does not transport energy or matter it "just" moves quantum states  
around.

It is however a significant result for quantum computing.

You can learn more at the "general reader" level ...

<http://www.research.ibm.com/quantuminfo/teleportation/>
<http://www.its.caltech.edu/~qoptics/teleport.html>
<http://en.wikipedia.org/wiki/Quantum_teleportation>

On Oct 5, 2006, at 4:49 PM, fontleroy at bainbridge.net wrote:

> Anybody see this article on moving light and matter 1/2 meter?
>
>
>
> http://www.cnn.com/2006/TECH/science/10/04/teleportation.reut/ 
> index.html
>
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--
Kevin Purcell
kevinpurcell at pobox.com