Nvidia CEO Jensen Huang offered a quantum-level climb-down on Thursday, after spooking quantum-computing companies earlier this year with his assessment that their efforts wouldn’t be “very useful” for 15 to 30 years.

Nvidia CEO Jensen Huang said he didn’t realise there were publicly traded quantum computing companies when he made earlier comments that caused industry stocks to crash. “My first reaction was, I didn’t know they were public. How can a quantum company be public?” Huang said at an event Thursday focused on the still-nascent technology.