Quantum computers should be powerful enough to crack Bitcoin’s security features—by instantly solving the mining mechanism or guessing wallet passwords by brute force—a few years after 2030, according to the CEO of a company working in partnership with Nvidia on its quantum computing efforts.
Quantum technology is not yet good enough to pose a threat to cryptocurrency, but it is getting there, Théau Peronnin, the CEO of Alice & Bob, told Fortune at Web Summit in Lisbon. (The company’s name is based on a joke about cryptography texts, which often state problems by using two fictional characters, Alice and Bob, who need to communicate with each other in secret.)
A&B—backed by about $150 million in venture capital—is developing a “fault-tolerant quantum computing” system with Nvidia. In classical computing, circuits at their most basic level are simple: Their gates are either open or closed, signaling a 1 or a 0. Quantum computing, however, uses a state of quantum physics known as “quantum uncertainty.” At an atomic level, a particle can exist as both matter and energy simultaneously. A computer using quantum principles can thus calculate as if it is representing 1 or 0 at the same time—allowing it to perform multiple tasks at the same time rather than in sequential order, and radically increasing the computer’s processing power.
The problem is that because quantum computers represent data in quantum states that are extremely fragile, the environment can disrupt their stability, introducing errors that have to be controlled and corrected. A&B is developing a system that solves that at the level of the hardware itself. A&B believes it can reduce the number of “physical qubits” needed to produce one “error-corrected logical qubit” from 1,000 to 1 today to as few as 20-1 in about five years’ time.
“The whole point of the approach is to embed the first layer of error corrections directly within the design of the quantum bit itself, the most elementary level of the machine, and that dramatically simplifies the whole system by up to 200-fold,” Peronnin said.
The end-product will be a system named “Graphene,” which Peronnin hopes will become available in 2030 as “the first machine that vastly outperforms classical supercomputers at nontrivial tasks.”
With Nvidia, A&B is “working hand in hand to build the framework for developers. What does it mean to program a quantum computer? How are all the middle layers that you need to stack on top of each other, from the extremely low level where you are talking voltages and frequencies, hertz and things like that, all the way to the absolute abstraction level … you have many levels to orchestrate. And this is what Nvidia is pushing, and we’re glad to support that effort,” he said.
“We’re making sure our hardware is compatible with their vision and fitting their vision with our requirements.”
Right now, though, quantum computers aren’t a threat to classical computing. “For all the foreseeable future, quantum computers will remain extremely small and extremely slow, and that’s really fun,” Peronnin said.
“The promise of quantum computing is an exponential speed-up, but if you zoom out on an exponential [curve], it’s dead flat—and then it’s a vertical wall. So we’re just at the beginning of the inflection. Now, it’s not any more powerful than your smartphone at the moment. But give it a couple of years, and it will be more powerful than the largest supercomputer ever.”
That will eventually pose a threat to Bitcoin and any other system that relies on cryptography for security, because quantum computers will be able to rip through their complicated encryption easily. And before that, digital assets may be threatened by a selloff if traders come to fear that they aren’t safe from the progress of quantum computing.
“You should have a few good years ahead of you, but I wouldn’t hold my Bitcoin,” Peronnin said, laughing. “They need to fork [move to a stronger blockchain] by 2030, basically. Quantum computers will be ready to be a threat a bit later than that,” he said.
Quantum doesn’t just threaten Bitcoin, of course, but all banking encryption. And it is likely that in all these cases companies are developing quantum-resistant tools to upgrade their existing security systems.
Defensive security algorithms are improving, Peronnin said, so it’s not certain when the blockchain will become vulnerable to a quantum attack. But “the threshold for such an event is coming closer to us year by year,” he said.
