About 80 years ago the world was at war. Under a veil of secrecy, scientists in Britain, Germany and the US created the first electronic computers. These computers filled rooms, required enormous amounts of electricity and made previously impossible calculations possible. Few of those involved could have imagined that decades later, computers that were an order of magnitude more powerful would fit in a backpack – and yet that is exactly what happened.
So now we’re on the threshold of really useful quantum computersCould we ever see quantum laptops? “I think it’s possible,” Mario Yellowa quantum computing researcher at the University of Oxford told LiveScience. “It’s highly speculative, but I can’t think of any fundamental reason why a quantum laptop wouldn’t be possible.”
Here are some steps needed to get there.
Scaling up qubit number
Before scientists can make a quantum laptop, they have to make a usable quantum computer, period. Questions remain about how much qubits – quantum equivalents of digital bits – are needed to create a truly useful quantum computer, or one that can solve a range of useful, real-world problems that arise the best superclassical computers. But it is certainly higher than is currently possible.
Stephen Bartletta theoretical quantum physicist and director of the University of Sydney’s Nano Institute, thinks we could see truly useful quantum computers by the end of this decade. “There are a lot of open scientific challenges, which makes that path a little murky, but we’re getting close,” Bartlett told LiveScience.
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For example, the newly developed quantum Charge-Coupled Device (QCCD) architecture could be used to create two-dimensional arrays of qubits instead of one-dimensional arrays – which would increase the density, and possibly the number, of qubits.
Reducing errors in quantum computers
But scaling brings another challenge to building a miniature quantum computer: correcting errors, or “noise.” “Our existing quantum components are noisy, so we need error correction, and that requires a large amount of redundancy,” Bartlett said. Scientists need to reduce errors or build error correction into quantum computers, and that requires even more qubits. Many scientists are trying to solve this problem.
For example, a December 2023 study tried to reduce errors by building a quantum computer with ‘logical qubits’. In another paperpublished in April 2024, scientists designed a new type of qubit that behaved like an error-correcting logic qubit. Some scientists have even proposed using photons (light particles) as qubits another study using a laser pulse. According to Peter van Loock, professor of theoretical quantum optics at the Johannes Gutenberg University of Mainz in Germany and co-author of the study, this approach has an “inherent ability to correct errors.”
So if powerful and useful quantum computers exist within a decade or two, the next step would be miniaturization.
Will quantum computers ever resemble laptops? (Image credit: Aitor Diago via Getty Images)
Choosing different types of qubits
But to get really small, quantum computers may need to focus on a different type of qubit than is currently popular. Some of today’s most advanced quantum computers – such as those from IBM and Google – rely on it quantum processing units filled with superconducting qubits. But the first quantum laptop probably won’t use this technology.
That’s because superconducting qubits naturally need to be cooled to a fraction above that absolutely zero – about 20 millikelvin – and that requires filling a room with dilution refrigerators. And companies like IBM aren’t trying to get around this size limitation. For example, IBM’s current one roadmap for quantum computing sets goals that include a 2,000-qubit quantum computer by 2033 – which would fill many rooms instead of one.
Quantum laptops could instead rely on trapped ion qubits, charged particles that are in multiple states at once and are suspended using electromagnetic fields, Bartlett and Gely explain. Although trapped ion systems operate at room temperature and don’t rely on room-sized refrigerators, the lasers they use are massive.
“Right now, our laser system covers about a cubic meter (35 cubic feet),” Gely said. “If we assume that ion traps are the future, then lasers have to become smaller.”
And lasers must not only become smaller, but also more advanced. Current systems aim to limit 100 ions. “How many qubits you can control with this amount of laser equipment is unclear,” says Gely. “You can control more qubits than we have now, but certainly not the millions of qubits of a full-fledged quantum computer.”
However, two recent developments may help with miniaturization. First, future QCCDs could promote miniaturization by increasing qubit density. Second, Stanford researchers created in July titanium-sapphire lasers that are 10,000 times smaller than the one they replace.
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Miniaturization efforts will increase
Right now, scientists are focused on making quantum computers more powerful, not shrinking them. “The push for miniaturization right now is not as strong as the push for performance, and that mimics the early days of conventional computing when we still had mainframes,” says Bartlett. “People thought the most powerful computers took up a building. And you know, why would anyone seriously consider carrying one in your backpack?”
The history of computers suggests that quantum computers will first be rolled out for industrial, military and government applications before shifting to consumers. The apocryphal quote from 1943 Thomas Watson Sr. that there would be a “world market for maybe five computers” comes to mind.
Of course, the global market for PCs and laptops is huge, so could there ever be a similar explosion in demand for quantum PCs and laptops? “The question I always get in my quantum computing classes is, ‘When can I play Doom on a quantum computer?’” Bartlett said. “But why would you want that when you can play Doom on your computer today?”
Instead, Bartlett suggested that there might be “quantum personal apps like finance or something niche around information security” – but the truth is no one knows. Gely made the alternative suggestion of a quantum processor in addition to a classical processor. “It might look like you have a graphics card, but it would only be useful for certain tasks,” Gely said.
It’s not yet clear whether quantum laptops would be useful to consumers. What experts can say with a high level of confidence is that all hardware obstacles – scaling the number of qubits, correcting errors and miniaturizing components – can be overcome. And yet, a future quantum laptop probably won’t play Doom.