2018/09/30 by Nicolas Gisin · 2 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.3390/e21030325
published as Entropy 2019, 21, 325 · Feature paper, Celebrating the Silver Jubilee of Teleportation (7 pages). V2 (March'19): Many typos corrected (sorry) and a few comments added
arxiv created 2019/03/26 · arxiv updated 2019/03/27
Twenty-five years after the invention of quantum teleportation, the concept of entanglement gained enormous popularity. This is especially nice to those who remember that entanglement was not even taught at universities until the 1990's. Today, entanglement is often presented as a resource, the resource of quantum information science and technology. However, entanglement is exploited twice in quantum teleportation. First, entanglement is the `quantum teleportation channel', i.e. entanglement between distant systems. Second, entanglement appears in the eigenvectors of the joint measurement that Alice, the sender, has to perform jointly on the quantum state to be teleported and her half of the `quantum teleportation channel', i.e. entanglement enabling entirely new kinds of quantum measurements. I emphasize how poorely this second kind of entanglement is understood. In particular, I use quantum networks in which each party connected to several nodes performs a joint measurement to illustrate that the quantumness of such joint measurements remains elusive, escaping today's available tools to detect and quantify it.