A topological alternative For the team at Nokia Bell Labs, the solution lies in better qubits rather than bigger machines.
Specifically, rather than information encoded in individual elementary particles, the team is focused on qubits that hold this same information in the way matter is spatially oriented—what is known as a topological qubit.
This alternative approach uses electromagnetic fields to manipulate charges around a supercooled electron liquid, triggering the qubits to switch between topological states and locking them in place for far longer periods of time.
It is inherently more stable as a result, explains Eggleston. “We have these electrons, and they're sitting in a plane, in one state. If I move them around each other, they're now in a different state. But that’s really hard to accidentally do, it doesn’t happen randomly. And so that allows you to build a stable system that you can control.”
In fact, while existing qubits have a lifespan of milliseconds, for topological qubits this could be several days, he adds. “It’s incredibly stable. Many, many orders of magnitude more stable.”
Some of the science that underpins the topological qubit dates back decades. In 1998 Bell Labs scientists Daniel Tsui and Horst Störmer were awarded the Nobel Prize in Physics for their discovery six years earlier of a counterintuitive physical phenomenon, later dubbed the fractional quantum Hall (FQH) effect. FQH refers to how electrons manipulated under strong magnetic fields and at very low temperatures can create new states of matter. These states are being leveraged nearly 40 years later to form the basis of topological qubits.
But in so many other ways, the push toward a topological qubit has placed scientists firmly in unknown territory. “The development of the technology can be frustrating because nobody’s done this before,” admits Eggleston. “It’s completely open sky. We’re often ahead of the theorists.”
“Nobody's ever actually shown you can control the topological state and switch it on and off. And that's what we're wanting to demonstrate this year. That’s what the scientists in our lab are working on as we speak.” Michael Eggleston, Research Group Leader, Nokia Bell Labs
That’s why the Nokia Bell Labs team has often worked collaboratively with the competition to advance the field. Much of the early research saw them work closely with Microsoft, for example. But they’re also hoping that 2025 will mark the year that sets their research apart.
In the coming months, the team at Nokia Bell Labs hopes to demonstrate their ability to control the qubit for the first time, intentionally moving it between states to offer enhanced stability and resilience against errors.
“That will be a first,” says Eggleston. “Nobody's ever actually shown you can control the topological state and switch it on and off. And that's what we're wanting to demonstrate this year. That’s what the scientists in our lab are working on as we speak.”
“Then next year, we'll build on that to show the quantum gating operations that you'd need to build a quantum computer,” Eggleston adds.
Recalculating the future of quantum computing If the Bell Labs team can reach these milestone moments, they will move closer toward a fully workable topological qubit that could prove transformative for the future of quantum computing.
Although the breakthrough may not shorten the timeline to a full-scale, fault-tolerant quantum computer, it will demonstrably alter the scale and scope of what quantum computers can achieve.
Topological qubits could unlock the future potential that has made quantum computing a topic of scientific fascination for years.
Rather than multi-billion-dollar machines that occupy entire buildings to deliver a mere fraction of the potential functionality, topological qubits could pave the way for far more efficient machines capable of tackling extremely complex optimization tasks and simulation problems with billions of variables at both microscopic and global levels.
In short, they could unlock the future potential that has made quantum computing a topic of scientific fascination for years.
Think about their application in chemistry, points out Eggleston, an area in which trial and error materially slows progress. “You have chemicals where it’s impossible to understand how they bind and interface with each other, and so teams synthesize, run tests, and see what works and what doesn't,” he explains.
“But when someone designs a bridge, they don’t just build a bunch and see which one doesn't fall down. Instead we have tools that allow you to simulate the mechanics of these giant structures, test them, and optimize them before you build anything. That’s what I see quantum computing being able to offer for the chemistry field,” Eggleston adds.
Such a breakthrough could also transform the design and development of lifesaving drugs, with quantum computers able to carry out molecular modelling for new therapeutic compounds at far greater speeds and levels of complexity than current computational methods allow.
And quantum systems could enable the simulation of exponentially more complex supply chains, crafting intricate digital twins that allow organizations to optimize operations. They could allow scientists to better predict the course of climate change, or develop advanced materials for use in aerospace. The use cases go on.
But before all that possibility can be materialized, a qubit that’s up to the task must come to fruition.
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