Re: Entanglement breaks new record
From: Sam Wormley (swormley1_at_mchsi.com)
Date: 07/30/04
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Date: Fri, 30 Jul 2004 23:55:13 GMT
sid myers wrote:
>
> Source: http://physicsweb.org/article/news/8/6/18
>
> Entanglement breaks new record
> 30 June 2004
>
> Physicists have succeeded in entangling five photons for the first time.
> Although four photons have been entangled before, five is the minimum
> number needed for universal error correction in quantum computation.
> Moreover, the same team has demonstrated a process called
> "open-destination teleportation" for the first time (Z Zhao et al. 2004
> Nature 430 54). The results represent a major breakthrough in efforts to
> exploit the laws of quantum mechanics in quantum information processing.
>
> By taking advantage of quantum phenomena such as entanglement,
> teleportation and superposition, a quantum computer could, in principle,
> outperform a classical computer in certain computational tasks.
> Entanglement allows particles to have a much closer relationship than is
> possible in classical physics. For example, two photons can be entangled
> such that if one is horizontally polarized, the other is always vertically
> polarized, and vice versa, no matter how far apart they are. In quantum
> teleportation, complete information about the quantum state of a particle
> is instantaneously transferred by the sender, who is usually called Alice,
> to a receiver called Bob. Quantum superposition, meanwhile, allows a
> particle to be in two or more quantum states at the same time.
>
> Jian-Wei Pan at the University of Heidelberg in Germany and colleagues at
> the University of Science and Technology of China in Hefei and the
> University of Innsbruck in Austria began by producing a high intensity and
> ultra-stable source of entangled photons. Next they used two entangled
> pairs of photons to generate a four-photon entangled state, which they
> then combined with a single-photon state. They were able to produce a
> five-photon entangled state by detecting the coincidence of five photons.
>
> To demonstrate open-destination teleportation, Pan and co-workers first
> teleported the unknown quantum state of a single photon onto a
> superposition of three photons. They were then able to read out this
> teleported state at any one of the three photons by performing a
> measurement on the other two photons.
>
> "Although our experiment might seem to be only a modest step forward, the
> implications are profound," Pan told PhysicsWeb. They plan to use their
> five-photon set-up to demonstrate "bit-flip error rejection" for quantum
> communication and to make a non-destructive controlled-NOT gate for
> quantum computation.
>
> Author
> Belle Dumé is Science Writer at PhysicsWeb
Posted here last month Physics News Update
Number 690 #2, June 30, 2004 by Phil Schewe and Ben Stein
http://www.aip.org/pnu/2004/split/690-2.html
But it's always nice to read another account. :-)
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