After the Million-Qubit Demo, Engineers Ask the Duller Question: Does It Last?

SINGAPORE — When the Singapore Institute ran a million-qubit processor across the Q-Net backbone on September 14, the headline was the number. This week the harder work is elsewhere: whether a machine that large can hold its computation long enough to be useful. "A record is a moment; a tool is a Tuesday," said Dr. Wei-Lin Tan, the physicist who narrated the demonstration and now cautions against reading it as a finished product. Quanta Lattice Systems, which builds the hardware, says its engineers are focused on error rates that climb steeply with scale — the reason no such processor yet runs a real workload unattended. The Q-Net itself, it bears repeating, secures the channel but sends nothing faster than light; entanglement locks the encryption, it does not carry a signal. Institute engineer Rahul Menon, who kept the September machine cold and coherent, put the milestone in its place. "We proved it can exist," he said. "We have not proved it can work by Friday."