DARPA Just Revealed the 2 Best Quantum Computing Stocks to Buy Now

The Defense Advanced Research Projects Agency (DARPA), the segment of the U.S. Department of Defense responsible for advancing technological innovations, recently announced which quantum computing companies had advanced to Stage C of its Quantum Benchmarking Initiative (QBI). The program was created to determine whether building a commercially viable fault-tolerant quantum computer by 2033 was feasible, and to support the efforts of the companies best positioned to achieve that goal.

Stage A began in 2024 with around 20 companies participating; each was awarded $1 million and tasked with providing DARPA with a concept for a credible path to creating a commercially useful quantum computer by 2033. Eleven companies later advanced to Stage B, where they needed to develop their plans in more detail and determine the risks and how they would mitigate them. In Stage C, the government will determine and validate whether the participants' quantum computers can be built and run as intended. Companies at that stage can be awarded up to $300 million in DARPA funding to support their work.

There is no predetermined number of winners that can reach Stage C. So far, though, six companies have advanced to it. Microsoft and PsiQuantum initially got the nod back in February 2025, while Diraq, Atom Computing, IonQ (NYSE: IONQ), and IBM (NYSE: IBM) just advanced to the final stage this month. Other companies in Stage B still have the opportunity to move on to Stage C; currently, Quantinuum (NASDAQ: QNT) is the only public company still in that group. Meanwhile, companies that are still in Stage A will also still have the chance to progress, and DARPA has made it clear that just because a company is at an earlier stage of the process, that shouldn't necessarily be seen as a knock on its technology.

Interestingly, though, each company to move forward in this latest round of advancements has taken a different approach to the fundamental technology of quantum computers -- how to create qubits. Atom Computing, which has a partnership with Microsoft, uses the neutral-atom approach. This is the same technique that Infleqtion employs, which takes individual uncharged atoms suspended in a vacuum and holds them in optical tweezers.

Diraq, meanwhile, deploys silicon spin qubits, which are composed of single electrons trapped inside electrostatic gates. Diraq boasts that its technology can be integrated into ordinary data centers, and asserts that its quantum computers will be highly affordable, costing less than a dollar per qubit.

But Diraq and Atom are privately held. You may find them intriguing, but you can't invest in them.

For investors, the focus should be on IonQ and IBM, which now have a leg up on other publicly traded quantum computing companies.

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IonQ

IonQ being chosen to advance to Stage C of DARPA's QBI is not surprising. With its trapped-ion qubit approach, the company has set the current record for the highest system accuracy, achieving 99.99% 2-qubit gate fidelity. That's meaningfully ahead of even its Stage C competitors.

Meanwhile, it recently announced another breakthrough, successfully demonstrating the industry's first end-to-end real-time quantum error-correction decoder. This helps set the stage for developing a fault-tolerant system.

With the QBI announcement, IonQ noted that quantum computing is about much more than hitting technical milestones, and said that it will work with DARPA to create a scalable system for a wide range of deployments. The company is already on its sixth-generation quantum computer, the Superion 256, and its recent acquisition of chip foundry SkyWater Technology gives it a vertical integration advantage that will help it create prototypes more quickly, and eventually scale its systems.

With the highest accuracy so far and plans to become a complete quantum ecosystem player, IonQ is one of the best bets in the quantum computing space today.

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IBM

Among large tech companies, IBM has been one of the most aggressive at pursuing the opportunity in quantum computing. It has an ambitious technological roadmap, projecting that its Starling System will become the world's first fault-tolerant quantum computer by 2029.

While IBM's quantum computers have not yet achieved the accuracy of IonQ's, its approach using transmon qubits, a type of superconducting qubit, produces exponentially faster results than IonQ's approach. Meanwhile, the company is developing a complete error-correction stack that uses both hardware and software, and includes techniques such as high-speed, independent qubit reset with its Nighthawk chip.

IBM is far from being a pure-play quantum computing company, but its future is tied to the technology. Given the resources it can bring to bear and the speed advantages that superconducting qubits offer, it is another quantum stock worth betting on.

Geoffrey Seiler has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends International Business Machines, IonQ, and Microsoft. The Motley Fool has a disclosure policy.