IonQ Cleared One of Quantum Computing's Biggest Hurdles. Should You Buy the Stock?

IonQ (NYSE:IONQ) has taken investors on a roller coaster ride in 2026. The quantum computing stock has seen multiple 20% swings in both directions. And the thrills are intensifying.

On Tuesday, Sept. 22, 2026, IonQ announced that it had cleared one of quantum computing's biggest hurdles by demonstrating the first end-to-end real-time quantum error correction decoder. Shares of the quantum computing pioneer soared in after-hours trading on the news, but gave up some of the gains shortly after the market opened on Wednesday. Is IonQ now a smart pick?

Image source: The Motley Fool.

Breaking down IonQ's breakthrough

Quantum computers offer tremendous potential. However, the systems are prone to errors because physical qubits (the basic unit of information in quantum systems) are highly sensitive to environmental noise. Quantum error correction is critical to make the technology useful in practical applications.

Companies, including IonQ, have attempted to solve this problem by deploying classical computers to decode the quantum errors. Unfortunately, these classical computers often become overwhelmed. The quantum computers then have to wait for the quantum error correction process to catch up. Such bottlenecks can significantly reduce quantum computers' processing speeds.

IonQ developed a dual-decoder architecture that runs on a single CPU. The company stated in a press release, "Under standard operational noise, IonQ's decoder introduced as little as 0.02% 'stretch' time. That means the decoding overhead added virtually no delay to the overall quantum computation."

In a nutshell, IonQ appears to have solved one of the most serious issues holding back the development of a large-scale commercial quantum computer. If you think that's a major breakthrough, you're right.

What it means for IonQ

IonQ projected full-year revenue of $280 million to $290 million in its second-quarter update on Aug. 5, 2026. Just over one month later, the company increased its revenue guidance to $450 million to $460 million on the heels of the closing of its acquisition of Skywater Technology.

Will IonQ's milestone quantum error correction achievement further boost its short-term revenue? Probably not. The quantum error correction breakthrough was demonstrated on simulated circuits rather than on physical hardware. The company hasn't yet announced a commercial product that uses its dual-decoder architecture.

However, the success could help IonQ over the longer term. The company's news will almost certainly generate plenty of buzz at the Quantum World Congress 2026, being held in Maryland from Sept. 23 through Sept. 26. This could lead to more customers interested in signing contracts with IonQ for 2027 and 2028.

Most importantly, IonQ's achievement helps validate its Walking Cat architecture, which serves as the foundation for fault-tolerant quantum computing using trapped ions. This gives IonQ momentum in delivering on its roadmap to build a quantum computer with 2 million physical qubits and 80,000 logical qubits by 2030.

Should investors jump aboard the IonQ train?

IonQ appears to be leading the pack among quantum computing companies, at least in quantum error correction. Is that enough for investors to buy the stock? Not necessarily.

Value investors likely wouldn't touch IonQ with a 10-foot pole. The stock trades at a whopping 56.5 times trailing 12-month sales. Even with its impressive revenue growth, IonQ remains priced at a steep premium.

It could be a different story for aggressive investors who aren't risk-averse, though. IonQ appears to share key characteristics that have propelled other growth stocks to soaring heights in the past.

The company is laser-focused on a hot technology with a potentially massive market opportunity. As we've already seen, IonQ is one of the early leaders. It has lined up an impressive roster of customers and partners, including Amazon (NASDAQ:AMZN), AstraZeneca (NYSE:AZN), and Nvidia (NASDAQ:NVDA). IonQ has also made acquisitions that differentiate it from the competition, notably including its recent purchase of Skywater.

To be sure, IonQ still faces plenty of risks. However, its latest achievement highlights the tremendous growth prospects that could lie ahead. This quantum computing stock is a buy -- at least for some investors.

Keith Speights has positions in Amazon. The Motley Fool has positions in and recommends Amazon, AstraZeneca Plc, IonQ, and Nvidia. The Motley Fool has a disclosure policy.