“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. 

The executive had said in January that “very useful” quantum computers are probably decades away, causing shares of IonQ Inc. and other companies to tumble. Thursday’s event — part of Nvidia’s weeklong GTC conference — invited some of those very companies on stage to discuss their prospects with Huang. 

The quantum-computing industry aims to use the unique properties of subatomic particles to process data much faster than traditional semiconductor-based electronics. The technical difficulties of building practical systems have meant that the field is still in an experimental stage. In addition to quantum upstarts, companies such as Microsoft Corp. and Alphabet Inc.’s Google are also trying find practical uses for quantum systems.

The companies on stage at Thursday’s event included IonQ and D-Wave Quantum Inc. Huang said it was natural for this new form of computing to take many years to develop since it was so novel. The companies might be able to convince him that quantum computing is happening more quickly than he expected, he said. “But I don’t know,” he joked.

“This whole session is going to be like a therapy session for me,” he said.

The six company leaders on stage gave him a variety of answers. Some argued that quantum computers are already in use to solve difficult science problems. Others posited that the technology is even closer to helping advance traditional computing.

Executives also said it wasn’t unreasonable to spend a decade honing a technology that will have such a large impact. Loic Henriet, who runs the French company Pasqal, argued that the term “quantum computing” was misleading. Quantum processors will help act as accelerators — working alongside traditional computers — rather than replacing them, he said.