Proceedings

EPJ D - Not one, not two, not three, but four clones!

First quantum cloning machine to produce four copies

Xi-Jun Ren and Yang Xiang from Henan Universities in China, in collaboration with Heng Fan at the Institute of Physics of the Chinese Academy of Sciences, have produced a theory for a quantum cloning machine able to produce several copies of the state of a particle at atomic or sub-atomic scale, or quantum state, in an article published in EPJ D. This could have implications for quantum information processing methods used, for example, in message encryption systems.

Quantum cloning is difficult because quantum mechanics laws only allow for an approximate copy—not an exact copy—of an original quantum state to be made, as measuring such a state prior to its cloning would alter it. In this study, researchers have demonstrated that it is theoretically possible to create four approximate copies of an initial quantum state, in a process called asymmetric cloning.

The authors have extended previous work that was limited to quantum cloning providing only two or three copies of the original state. One key challenge was that the quality of the approximate copy decreases as the number of copies increases. The authors were able to optimise the quality of the cloned copies, thus yielding four good approximations of the initial quantum state.

They have also demonstrated that their quantum cloning machine has the advantage of being universal and therefore is able to work with any quantum state, ranging from a photon to an atom.
Assymetric quantum cloning has applications in analysing the security of messages encryption systems, based on shared secret quantum keys. Two people will know whether their communication is secure by analysing the quality of each copy of their secret key. Any third party trying to gain knowledge of that key would be detected as measuring it would disturb the state of that key.

Optimal asymmetric 1 –> 4 quantum cloning in arbitrary dimension.
XJ Ren, Y Xiang and H Fan , Eur. Phys. J. D (2011), DOI 10.1140/epjd/e2011-20370-2

In the last years, I contributed to organize different scientific events with the University of Messina and the Bonino-Puleio foundation and with the support of the INFN. In the most of cases, we decided to publish the proceedings in the EPJ Web of Conferences. The main reasons of this choice are: the cost of the publication is very competitive with respect the other publisher (important to justify the expense with the own administration), the quality of the services are excellent from different points of view: the publishing editor and Collaborators are kind to furnish very soon all information and to process all requests, they are able to publish the proceedings in very short time and with high quality. The journal provides also citation indexing via ISI Web of Knowledge and Scopus, very important for the visibility of the articles and the authors.

Giuseppe Mandaglio, University of Messina, Italy
Co-editor EPJ Web of Conferences vol. 142 (2017)

ISSN: 2100-014X (Electronic Edition)

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