IonQ (NYSE:IONQ), a full-stack trapped-ion quantum computing provider, closed at $42.54, up 4.42%. It rose after a real-time error-correction breakthrough and a research-center collaboration with Nvidia (NASDAQ:NVDA).
Trading volume reached 69.9 million shares, coming in about 233% above its three-month average of 21.0 million shares. IonQ IPO'd in 2021 and has grown 294% since going public.
The S&P 500 (SNPINDEX:^GSPC) fell 0.75% to 7,706, and the Nasdaq Composite (NASDAQINDEX:^IXIC) fell 1.13% to 26,936. Among quantum computing hardware, software, and cloud-access services peers, Rigetti Computing (NASDAQ:RGTI) closed at $16.00, down 3.12%, and D-Wave Quantum (NASDAQ:QBTS) closed at $16.81, down 4.27%, as the group tracked IonQ's decoder news.
IonQ defied a tech downturn today on company-specific news, prompting investors to bet that its quantum computing developments signal a leadership position in the space. The company announced a breakthrough in error decoding with what it called "the industry's first end-to-end real-time quantum error correction decoder that runs on a single standard off-the-shelf central processing unit (CPU)."
In addition to that news, IonQ announced a potentially important step toward commercializing its quantum systems. Its Superion 256 system will be installed in Nvidia's accelerated quantum research center to run as a niche processing system alongside Nvidia GPU (graphics processing unit) clusters.
That could lead to hybrid developments and create large-scale systems for AI use cases that include both GPU and quantum designs. That has investors feeling more confident about IonQ's future commercial success.
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Howard Smith has positions in Nvidia. The Motley Fool has positions in and recommends IonQ and Nvidia. The Motley Fool has a disclosure policy.