A Month On, the Million-Qubit Machine Is Still Learning to Stay Cold

SINGAPORE — Four weeks after the Singapore Institute ran a million-qubit processor across the Q-Net backbone, the harder story is unfolding quietly in the cryogenics bay. Sustaining coherence at that scale, engineers say, means fighting heat and vibration around the clock, and the machine still spends more hours being stabilized than computing. "A demonstration is a photograph; a useful machine is a habit," said Dr. Wei-Lin Tan, the Institute physicist who has become the program's public voice, cautioning against reading the milestone as an arrival. He is equally firm on what the Q-Net does not do: it secures the channel through quantum-key distribution — unbreakable encryption over the classical network — and carries no faster-than-light message. For engineer Mei Sato, watching the dilution refrigerator hold its line, the win is smaller and truer: "It stayed cold long enough to matter. Tomorrow we do it again."