Repeated communication through the mechanism and

Olivia Nicoletti

Xiang-sheng Wu

This paper studies the quantum repeater in quantum information communication. We propose to introduce the photon buffer mechanism for storing photons, which uses fibre delay loops as photon memories and a programmable 1×N switcher for distributing photon delay time. Meanwhile, we also consider entanglement purification and entanglement swapping restoration at an entanglement purification or entanglement swapping failure and introduce a protection link mechanism that allows the photonic quantum repeater of a broken connection to initiate a connection restoration process.

Peishun Yan, Lan Zhou, Wei Zhong +1 more

Abstract The distribution of quantum entanglement is essential for quantum communication. Contrary to classical communication, the signal in quantum communication is impossible to copy due to the basic principles of quantum mechanics, i.e. , quantum state collapse and no-cloning theorem. However, the communication range is limited by inevitable photon loss. To counteract this issue, one can insert several repeater stations between two remote end nodes to divide the full distance into several shorter segments and successively operate entanglement swapping between adjacent repeater stations to enable long-distance quantum communication. Up to now, one can classify quantum repeaters (QRs) into three generations based on the methods of reducing errors resulted from photon loss and imperfect operations. In this paper, we will briefly review advances for each generation of QRs and discuss the advantages and challenges of each generation. Moreover, we also discuss some efficient proposals of building blocks to overcome the bottlenecks for QRs.

Indranil Chakrabarty, Prashant ., Binayak Samadder Choudhury

A. Taroni

Olivier Gossner, Nicolas Vieille

We consider the "and" communication mechanism that inputs messages from two players and outputs the public signal "yes" if both messages are "yes", and outputs "no" otherwise. We prove that no correlation can securely be implemented through finite or infinite repetition of this mechanism.