Nvidia launch sends quantum stock surging 251%, mints billionaire

By TheStreet Roundtable

about 2 hours ago

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A man who twice flunked out of film school in Australia and briefly stocked grocery shelves for a living is suddenly one of Canada’s newest billionaires.

On April 18, Christian Weedbrook, the founder and chief executive of Toronto-based Xanadu Quantum Technologies, saw his stake in the photonic quantum computing company balloon to roughly $1.5 billion by midday Friday, according to regulatory filings and market data compiled by Bloomberg.

The windfall came in a matter of trading sessions, triggered almost entirely by one announcement out of Santa Clara.

Nvidia, the chip giant that has ridden the artificial intelligence boom to become one of the world’s most valuable companies, released on April 14 a family of open-source AI models called Ising.

The models are built to tackle two of the thorniest engineering problems in quantum computing: processor calibration and real-time error correction. Nvidia says the Ising decoding models are up to 2.5 times faster and three times more accurate than pyMatching, the open-source decoder most quantum researchers currently rely on.

For a sector that had been battered through much of early 2026, the news landed like a defibrillator.

Shares of nearly every publicly traded quantum name — D-Wave, IonQ, Rigetti, Quantinuum-linked tickers — jumped. But none moved like Xanadu.

A five-day rally that broke circuit breakers

Xanadu, which only began trading publicly on March 27 after merging with a special purpose acquisition vehicle called Crane Harbor Acquisition Corp., had spent most of its brief public life drifting below $10 a share. The stock closed just under $8 on the session before Nvidia’s announcement.

By Friday afternoon, it was changing hands at $31.41 in New York, up 251% from the previous week’s close, and had traded as high as $40 earlier in the rally. The Canadian Investment Regulatory Organization halted trading on the Toronto Stock Exchange five separate times on Thursday alone, citing rapid and unexplained price movement under its single-stock circuit breaker rule. At one point during that session, the stock was up more than 65%.

The company’s market capitalization briefly crossed $16 billion, making Xanadu one of Canada’s most valuable publicly traded technology firms only three weeks after its Nasdaq and TSX debut.

Weedbrook owns 15.6% of Xanadu’s shares through 46.4 million multiple voting shares, according to a March 26 filing with the US Securities and Exchange Commission.

Other early backers also came out ahead. The Ontario Municipal Employees Retirement System, a pension fund for municipal workers in Canada’s most populous province and Xanadu’s first institutional investor, controls roughly 40.2 million shares that were worth more than $1 billion at midweek. Bessemer Venture Partners and Georgian Partners, two venture firms that wrote early checks, are also sitting on substantial paper gains.

Running a quantum race

Weedbrook’s path to a ten-figure net worth is unusual even by the standards of the tech industry. Born and raised in the bushland southeast of Brisbane, Australia, he tried to be a filmmaker in his twenties and failed out of film school — not once, but twice. He worked at a video store and stocked groceries before deciding, at 23, to give postsecondary education another try.

He was good at math in high school, so he picked that. Officials at the University of Queensland, where he enrolled, were skeptical enough that one dean asked to check his arms for track marks, suspecting drug use.

“I’d exhausted every other option,” Weedbrook, now 49, told The Globe and Mail earlier this year. “I thought ‘I’ll just go back to something I was okay in — math.’”

That decision turned out to matter. Queensland happened to be one of the best places in the world to study quantum optics — the science of how light behaves at subatomic scales.

Weedbrook earned a doctorate in physics there, specializing in quantum information theory, spent a brief stint at the Massachusetts Institute of Technology, and transferred to the University of Toronto in September 2010 for postdoctoral work. He decided he wanted to stay in Canada. He started a company in 2014, initially called CipherQ, that eventually became Xanadu.

The firm’s technical approach sets it apart. While most quantum computers being built today — by IBM, Google, IonQ and others — rely on superconducting circuits or trapped ions that need to be kept at temperatures colder than deep space, Xanadu uses photons, the fundamental particles of light, sent through fiber-optic connections.

That means its system can operate at room temperature, which in theory makes it cheaper and easier to scale.

Xanadu has published four papers in the journal Nature documenting its breakthroughs. In 2025, the company advanced to the second stage of a US Defense Advanced Research Projects Agency competition that challenges developers to prove their quantum machines will work by 2033.

Xanadu has also been selected for Canada’s Quantum Champions Program, which could deliver up to CAD $23 million in federal support, and is in negotiations over as much as CAD $390 million under a separate Ontario manufacturing initiative called Project OPTIMISM.

The company introduced a modular, networked photonic quantum computer called Aurora earlier this year, which it says performs real-time error correction, and it runs an open-source software platform called PennyLane that is widely used in academic quantum research.

Still, Xanadu is a long way from a real business. The company reported revenue of just $4.6 million last year against $55.2 million in research and development expenses in 2025. Profits are not expected anytime soon.

Wall Street warns the rally may be running ahead of reality

The sheer scale of the move has some analysts nervous.

“Quantum stocks were oversold which formed this 'coiled spring' condition where any positive news or breakthrough could have the potential to shift sentiment,” Antoine Legault, an analyst at Wedbush Securities, told Bloomberg. He added that quantum computing stocks have historically been extremely volatile.

Legault cautioned that if investor excitement over Nvidia’s Ising models fades into harder questions about how quantum companies will actually translate the tools into commercial products, some of the rally could be given back.

“It remains to be seen whether quantum computing companies will use these tools to their benefit and if it will indeed accelerate the timeline to commercialization,” he added.

Part of what has fueled the move in Xanadu specifically is simple supply and demand.

The majority of the company’s shares are held by private investors and employees and are covered by a lockup agreement that does not expire until September. Only a minority of the stock is available to trade, which tends to exaggerate price swings.

Jensen Huang, Nvidia’s founder and chief executive, echoed the bigger-picture argument when Ising launched. “AI is essential to making quantum computing practical,” he said in a statement.

“With Ising, AI becomes the control plane — the operating system of quantum machines — transforming fragile qubits to scalable and reliable quantum-GPU systems.”

What the quantum leap means for Bitcoin

Every dollar added to a quantum company’s market cap this week also sharpened a much older conversation inside the crypto industry — the one about whether Bitcoin’s cryptography can survive what is coming.

Bitcoin’s security relies on a math problem called the 256-bit elliptic curve discrete logarithm problem, or ECDLP-256. It is the backbone of the elliptic curve digital signature algorithm that protects every wallet and every transaction on the network.

A sufficiently powerful quantum computer running Shor’s algorithm could, in theory, reverse-engineer a private key from an exposed public key, something classical computers cannot meaningfully do in any human timescale.

On March 30, researchers at Google Quantum AI, the Ethereum Foundation and Stanford University published a paper arguing that the number of physical qubits needed to break that encryption is roughly 20 times lower than previously estimated — under 500,000 qubits, rather than the millions researchers had modeled before.

Google has also warned that a sufficiently advanced quantum machine could theoretically derive a Bitcoin private key from a public key during the brief window between when a transaction is broadcast and when it is confirmed on chain. The company has set a 2029 deadline to migrate its own authentication systems to post-quantum cryptography.

John M. Martinis, the Nobel Prize-winning physicist who helped build Google’s early quantum computers, told CoinDesk this month that Bitcoin could be among the first real-world targets of a cryptographically relevant quantum machine.

“It turns out that breaking cryptography is one of the easier applications for quantum computing, because it’s very numeric,” he said. “These are the smaller, easier algorithms. The low-hanging fruit.”

Martinis estimates a rough five-to-ten-year window for that kind of hardware to exist.

The Bitcoin community is, predictably, not of one mind about what to do.

BitMEX Research has floated a so-called quantum tripwire that would pay a bounty to the first successful quantum attacker and automatically freeze vulnerable coins only if an attack is proven.

Jameson Lopp has pushed a proposal that would phase out Bitcoin’s original security methods and freeze coins that do not migrate in time.

Earlier this week, Adam Back, the chief executive of Blockstream, told Paris Blockchain Week that he favors optional quantum-resistant upgrades rather than a forced freeze of old coins. Ethereum, by contrast, has already set up a dedicated quantum research team under the Ethereum Foundation and begun designing its next protocol iterations around post-quantum signature schemes.

Coinbase has assembled an independent advisory board of cryptographers, academics and quantum computing experts to guide its own preparations. Cathie Wood’s Ark Invest has pushed back on the more alarmist framing, arguing the risk is real but distant. Jefferies, for its part, has told clients the threat is serious enough that investors should consider dropping Bitcoin from their portfolios altogether until the protocol migrates.

Xanadu’s approach, photonic quantum computing at room temperature, is exactly the kind of architecture that quantum researchers believe could scale fastest. Weedbrook has said the company aims to build one of the first quantum data centers by 2030.

That timeline, if it holds, lands squarely inside the five-to-ten-year window that physicists like Martinis have flagged as the danger zone for elliptic curve cryptography.

A billionaire was minted this week on the promise of quantum computers that work. The question for roughly $1.4 trillion worth of Bitcoin is what happens when they do.