NEW YORK—A team of quantum computing engineers from JPMorgan Chase & Co., Toshiba Corp. and Ciena Corp. say they have successfully shown that a powerful, newly-developed encryption network can be used to protect communications on the blockchain, according to a paper published Thursday. The group of researchers say it is the first time that a quantum key distribution (QKD) network, a super-secure two-way communication network powered by quantum physics, has been tested as a way to protect the blockchain from quantum computing attacks. Quantum computers, which can process information and calculations at a radically faster rate than classical computers, are still being developed, and so experts say quantum computing cyberattacks are still some years away. But the threat they pose is so great that researchers like those at JPMorgan are searching for ways to protect banking systems now. “Security is paramount for JPMorgan Chase,” said Marco Pistoia, head of JPMorgan’s …