Singapore's Q-Net Upgrade Promises Unbreakable Lines — and Reopens the Privacy War

SINGAPORE — The Singapore Institute switched a hardened segment of the Q-Net into service this week, extending quantum-key distribution across a stretch of the backbone that had run on legacy encryption for a decade. On the engineering merits the case is settled: a line secured this way cannot be quietly read, because any attempt to listen disturbs the keys and announces itself. "The channel keeps its own honesty," said Dr. Wei-Lin Tan, walking a delegation past racks of humming lattice hardware. "No one eavesdrops on this without ringing the bell." But an unreadable line is only as private as the institutions that operate its endpoints, and that is where the old fight reopened. Civil-liberty groups pressed a single question through the week: if the pipe is perfect, who audits the people at either end of it? "Unbreakable is not the same as unwatched," one advocate warned. The physics, as ever, is the easy part.