Rigetti Computing is at the forefront of the quantum computing industry, but the company has a speculative stock valuation.

The shares of IonQ Inc. and other companies linked to quantum computing tumbled in extended trading on Tuesday after Nvidia Corp. Chief Executive Officer Jensen Huang said “very useful” quantum computers are likely decades away.

Rigetti Computing (RGTI) is an integrated full-stack quantum computing company that focuses on designing and developing quantum chips. It was the first company to develop a multi-chip quantum processor.