Shanghai Physicists’ Eight-Tailed Schrödinger’s Cats
Ars Technica describes the reliable quantum entanglement of groups of eight photons by researchers at Shanghai’s University of Science and Technology of China, following their publication of a paper in Nature Photonics. The achievement marks an incremental but likely significant step towards practical quantum computing.
A significant step forward has been accomplished by entangling eight photons (previously six had been the largest number). Researchers from Shanghai’s University of Science and Technology of China created a system where eight photons were equally likely to be polarized in a specific orientation, something known colloquially as a “Schrödinger cat” state. In a paper published in Nature Photonics, authors Xing-Can Yao et al. describe a new technique that uses ultra-bright photon sources to control for some of the problems that plagued earlier entanglement experiments ….
Eight photon entanglement is in a way incremental progress; previous experiments have measured six photon entanglement, and this particular setup is sufficiently more complex to beg the question of scalability. However, the system is also powerful enough that it is a step forward in terms of optical quantum computation. The authors suggest that their setup may enable quantum simulations to tackle more complicated problems in condensed matter physics than have been possible so far. By exploiting other aspects of the photons’ states besides polarization, additional aspects of entanglement may be explored and used for future quantum computing applications.
An overlapping Chinese team achieved quantum teleportation over an unprecedented distance of ten miles in 2010. Author William Gibson noted the occasion in a talk soon afterwards:
In quantum teleportation, no matter is transferred, but information may be conveyed across a distance, without resorting to a signal in any traditional sense. Still, it’s the word “teleportation”, used seriously, in a headline. My “no kidding” module was activated: “No kidding,” I said to myself, “teleportation.” A slight amazement.
See explanations of quantum entanglement and teleportation at Wikipedia and the Stanford Encyclopedia of Philosophy, and take comfort in Richard Feynman’s possibly apocryphal proclamation that “if you think you understand quantum mechanics, you don’t understand quantum mechanics.”