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Photon teleportation

June 01, 2010 By: admin Category: Science and Technology

http://www.nature.com/nphoton/journal/v4/n6/abs/nphoton.2010.87.html

It provoked some questions in my mind (below).


Nature Photonics 4, 376 – 381 (2010)
Published online: 16 May 2010 | doi:10.1038/nphoton.2010.87

Experimental free-space quantum teleportation

Xian-Min Jin1, Ji-Gang Ren1,2,3, Bin Yang1, Zhen-Huan Yi2, Fei Zhou2, Xiao-Fan Xu1, Shao-Kai Wang2, Dong Yang2, Yuan-Feng Hu1, Shuo Jiang2, Tao Yang1, Hao Yin1, Kai Chen1, Cheng-Zhi Peng2 & Jian-Wei Pan1,2


Abstract

Quantum teleportation1 is central to the practical realization of quantum communication2, 3. Although the first proof-of-principle demonstration was reported in 1997 by the Innsbruck4 and Rome groups5, long-distance teleportation has so far only been realized in fibre with lengths of hundreds of metres6, 7. An optical free-space link is highly desirable for extending the transfer distance, because of its low atmospheric absorption for certain ranges of wavelength. By following the Rome scheme5, which allows a full Bell-state measurement, we report free-space implementation of quantum teleportation over 16 km. An active feed-forward technique has been developed to enable real-time information transfer. An average fidelity of 89%, well beyond the classical limit of 2/3, is achieved. Our experiment has realized all of the non-local aspects of the original teleportation scheme and is equivalent to it up to a local unitary operation5. Our result confirms the feasibility of space-based experiments, and is an important step towards quantum-communication applications on a global scale.

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  1. Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui, 230026, PR China
  2. Physics Department, Tsinghua University, Beijing 100084, PR China
  3. These authors contributed equally to this work.

Correspondence to: Cheng-Zhi Peng2 e-mail: pcz@mail.tsinghua.edu.cn

Correspondence to: Jian-Wei Pan1,2 e-mail: pan@ustc.edu.cn

Question(s)?  Heisenberg’s Principle of Uncertainty

How do the authors demonstrate that the “change(s)” in the “remote” particle – (I guess the observed changes in the energy “state” of the remote twin photon) is/are NOT simply due to the effect of the measurement – as per Heisenberg’s Principle of Uncertainty, i.e. that the “different” state of the “doppelganger particle” is not due to the interaction between the measurement instrument and the twin photon?

Isn’t this principle / methodology precisely used in securing / verifying the integrity of encrypted messages transmitted via fiber optic lines? Isn’t the idea that any intercept of the encrypted message would result in change in the photon “status” (“state”) – and show the transmission was “hacked?”

Starting point: 1. Identity of the twin photon?  How is it established (measured?) – without disturbing it (Heisenberg)?

And then, 2. After a change was imparted to the first (local) photon, how is this precise change observed / measured / shown / demonstrated on the “remote” one, again considering Heisenberg?

(Who said “Ce qui se concoit bien, s’explique clairement” ?)

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