Generation of one-million-mode continuous-variable cluster state by unlimited time-domain multiplexing,” by Jun-ici Yoshikawa, Shota Yokoyama, Tishiyuki Kaji, Chanond Sornphiphatphong, Yu Shiozawa, Kenzo Makino and Akira Furusawa, APL Photonics, September 27, 2016, scitation.aip.org/content/aip/journal/app/1/6/10.1063/1.4962732.
When the quantum computer was imagined 30 years ago, it was revered for its potential to quickly and accurately complete practical tasks considered impossible for conventional computers. But, there was one big catch: Tiny-scale quantum effects fall apart too easily to be practical for reliably powering computers. Now, a team of scientists in Japan may have overcome this obstacle. Using laser light, they have a precise, continuous control technology giving 60X more success than previous efforts in sustaining the lifetime of “qubits,” . In particular, they can continue to create an entangled state—entangling >1million different physical systems, a world record that was only limited in their investigation by data storage.
“There is a problem of the lifetime of qubits for quantum information processing. We have solved the problem, and we can continue to do quantum information processing for any time period we want,” explained Akira Furusawa, of the Department of Applied Physics, School of Engineering at the University of Tokyo and lead researcher on the study. “The most difficult aspect of this achievement was continuous phase locking between squeezed light beams, but we have solved the problem.”
Quantum computers process information by harnessing the remarkable power of quantum mechanics that encodes 0s and 1s in quantum states called qubits. Qubits configure in two unusual ways: “superposition” and “entanglement.” Einstein himself characterized entanglement as “spooky action at a distance.”
Start with the fact that quantum systems can be in several states simultaneously—the up and down of superposition, for example. Particles also exhibit the quantum behavior of entanglement. It is a deeply intimate property between quantum particles that unites them perfectly in a shared existence, even at immense distance. In other words, spooky. And it is this spooky action—entanglement—that the University of Tokyo team discovered how to manage so it can be applied to run quantum computers.
For the next steps on this promising path toward making quantum computing practical, Furusawa envisions creating 2D and 3D lattices of the entangled state. “This will enable us to make topological quantum computing, which is very robust quantum computing,” he said.
http://phys.org/news/2016-09-quantum-advances-entanglement.htmljCp
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