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.

Investors have been cheering on quantum computing stocks, and companies such as IonQ, Rigetti Computing, and Quantum Computing have drawn a good deal of attention. Whenever an exciting new opportunity starts to become mainstream,

Quantum computing has received some recent investing interest over the past month thanks to Google's breakthrough in its Willow quantum computing chip. Alphabet (NASDAQ: GOOG) (NASDAQ: GOOGL) is a much larger business with investments in quantum computing,

Defiance Quantum ETF returned 60.4% over the last year through Jan. 3 -- just over double the S&P 500 Index's 28.1% return.

Quantum computing stocks dived after Nvidia CEO Jensen Huang said Tuesday night that the tech won't be "very useful" for 15-30 years.