Quantum technology holds out the promise of transforming computing by producing enormous gains in processing power. But it's a technology under development with no real certainties about the future. We look at some of the contenders for quantum supremacy. By Mackenzie Tatananni

Quantum computing has graduated from a theoretical curiosity to a stock market phenomenon. The sector's shares routinely post some of the biggest moves in the market, up and down, as investors place their bets on the future of computing.

Quantum computers, offshoots of quantum mechanics, can explore multiple solutions at once, and promise the kind of processing power that could revolutionize medicine, materials science, and other fields.

The technology is unquestionably tricky for investors. The pure-play stocks -- the shares of companies that concentrate their efforts wholly on quantum computing -- trade mostly on sentiment, since none of the companies have yet to turn a profit. Most are burning cash as they develop products.

The performance of the stocks has been all over the map. D-Wave Quantum last year more than tripled and Rigetti Computing rose 45%, handily outstripping a 20% gain for the tech-heavy Nasdaq 100. IonQ rose just 7.4%, while Quantum Computing lost 38%. Such varied outcomes suggest idiosyncratic stories, rather than industry tides, are dictating the winners and losers.

Valuations tell a tale of two worlds. IBM, a tech mainstay with a robust quantum effort, is trading at a measured 2.9 times forward sales. Hype has pushed Rigetti Computing and D-Wave to price-to-sales ratios of 746 and 268, respectively.

Numbers like that aren't for the faint of heart. But by many accounts, the industry is about to take off. Barclays anticipates that quantum systems will achieve a definitive edge over traditional computers by 2027, provided their capabilities hold up under intense technical scrutiny. Estimates from McKinsey project the market will grow to anywhere from $43 billion to $72 billion by 2035.

As the future of quantum computing starts to take shape, there are plenty of ways to play it. Here are six stocks worth considering.

IonQ

IonQ: This is the largest publicly traded pure play by market capitalization -- and one of the boldest. CEO Niccolo de Masi famously referred to the company as the "Nvidia player" of quantum. Last year, the company became the first quantum company to surpass $100 million in annual revenue under generally accepted accounting principles. First-quarter earnings further demonstrated its growth, as IonQ reported a narrower-than-anticipated loss and a sharp spike in contracted backlog, a clear sign of accelerating demand.

D-Wave Quantum

D-Wave Quantum: The company has cornered the market for "annealing quantum," an approach tailored to optimization tasks like logistics and data sampling. However, D-Wave is targeting the launch of a superconducting "gate model" system this year. This more versatile approach uses ultracold electrical circuits to store data, and timed pulses of microwave energy to perform calculations. Revenue fell 81% in the first quarter due to a system sale in the prior year, but Jefferies' Kevin Garrigan noted that "the underlying momentum remains." D-Wave posted record bookings and increased its system sales from one a year to two or three.

Rigetti Computing

Rigetti Computing: After a monthslong delay, Rigetti released its largest quantum system to date in April. The company is taking time to refine its technology before scaling to bigger systems, which has led to several readjustments of its timelines. To reduce its dependency on research and development contracts from U.S. government agencies, Rigetti is prioritizing sales of its machines. The company sold a 9-qubit Novera processor to a Canadian university in March, just months after an $8.4 million sale to a research institution in India.

IBM

IBM: As a cornerstone of the quantum ecosystem, Big Blue offers cloud-based access to its vast quantum fleet and maintains Qiskit, an open-source development kit enabling users to build quantum computing programs. Morgan Stanley analyst Erik Woodring tells Barron's the market is likely "discounting or underwriting some degree of quantum in the stock price." While IBM's scale and diversification usually reduce volatility, shares popped when the company unveiled its road map to achieve fault-tolerant quantum supercomputing by 2029.

Xanadu Quantum Technologies

Xanadu Quantum Technologies: Less than two months after its U.S. trading debut, Xanadu stock cratered when the company filed a prospectus allowing shareholders to register their stock for sale. The selloff reflected market anxiety over an increase in shares rather than perceived flaws in the business itself. Xanadu is betting on photonic quantum computing, which uses light particles to carry and process information. This model can operate at room temperature, potentially offering a faster route to stable, large-scale systems. Revenue increased fourfold in the latest quarter, with Xanadu citing continued adoption of its popular software platform, PennyLane.

Quantum Computing

Quantum Computing: This company is no stranger to uncertainty, given that it spent months searching for a permanent CEO before promoting Yuping Huang in January. The company has faced scrutiny from short sellers who claim it fabricated revenue and misled investors about its quantum chip foundry. To date, Quantum Computing hasn't acknowledged these claims. First-quarter earnings may have shifted sentiment, as shares jumped 16% despite mixed results. The company has signaled its intentions to scale its presence in quantum communications and photonics through recent acquisitions of Luminar Semiconductor and NuCrypt.