Better Quantum Computing Stock to Buy: IonQ vs. Rigetti

Quantum computing is an exciting technology that's looming in the distance. There are countless breakthroughs happening in this field, and the technology could start to make an impact soon, with many estimates pointing toward 2030 as the year when quantum computing becomes commercially viable. If that's the case, then investors need to be positioned in the winning stocks years before 2030, as that's when the biggest gains will occur.

There are two primary types of quantum stocks: legacy players and pure-play start-ups. Legacy players include companies like Alphabet and IBM that have existing businesses with established cash flows that can throw a ton of money at this technology to make it viable. While those still exist and promise quantum computing investments, if they produce a commercially viable product, it won't have as great an effect on their long-term results as it would for some of the smaller companies.

The pure-play start-ups are smaller companies that have to produce a viable quantum computing product or else risk going bankrupt. While these investments are riskier, the upside is far greater. Two of the market's favorite quantum computing pure-plays are IonQ (NYSE: IONQ) and Rigetti Computing (NASDAQ: RGTI). If either or both of these pan out, the upside could be enormous, but which is the better buy?

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Each is taking a different path

There isn't one established way to do quantum computing. The base idea is to harness the quantum mechanics of a particle and manipulate it into doing various computations, but how that's done is different from company to company. The most common way to perform quantum computing is by using a process called superconducting. This involves cooling a chamber to near absolute zero, then utilizing a slowed-down particle to perform calculations. This is the path that many of the legacy tech players are taking, as is Rigetti. Superconducting's advantage is that it allows for high-speed calculations, but its disadvantage is that it's currently inaccurate.

Rigetti's recently launched 108-qubit system has a median 2-qubit gate fidelity of 99.1%. That means users can expect an error 0.9% of the time when a calculation passes through two operations. That's not quite good enough for commercial products, and IonQ has a leg up in this area.

IonQ utilizes a technique known as trapped-ion, which uses lasers to cool the particle precisely. The trapped-ion approach is essentially the opposite of superconducting, as it provides high-accuracy, low-speed computers. Back in October 2025, IonQ achieved 99.99% 2-qubit gate fidelity, and this technology will be integrated into its 256-qubit system, of which there has already been one sale.

IonQ's technology is more accurate and offers greater computational capacity (more qubits). That gives IonQ the edge here, although breakthroughs and advancements could easily shift the balance in Rigetti's favor over the next few years.

Winner: IonQ

IonQ has a much stronger financial position

Comparing financials, it's clear that IonQ's product is getting a lot more attention. Its Q1 revenue rose 755% year over year to nearly $65 million. While some of that growth came from acquisitions, it's still seeing increased partnerships and greater system sales than Rigetti is.

Rigetti's revenue rose from $1.47 million in Q1 2025 to $4.4 million in the same quarter of 2026, but that's just a fraction of IonQ's sales. This tells me that the market is more excited about IonQ's products than Rigetti's, and unless Rigetti can turn it around, I'm inclined to declare IonQ the overall winner.

Winner: IonQ

The leaders now may not be the leaders of tomorrow

While I think IonQ is by far the better quantum computing stock to buy now, there's no saying that Rigetti can't catch up or that IonQ won't hit a roadblock. The sector is still a ways from producing viable quantum computing at a widespread scale, which could give others time to catch up. That's why investing in a basket of quantum computing stocks or a quantum computing exchange-traded fund (ETF) is a smart idea, as it spreads your investment across multiple companies.

Quantum computing is coming, and there are several ways to capitalize on it. While I'm a huge fan of IonQ right now, there are also several lower-risk ways to play this space. If you do choose to invest in a stock like IonQ, ensure that the position size is small enough that it going to $0 won't affect your portfolio too much, as the risk of failure still exists.

Keithen Drury has positions in Alphabet and IonQ. The Motley Fool has positions in and recommends Alphabet and IonQ. The Motley Fool has a disclosure policy.