By | November 13, 2023
A square ion trap seen through the circular window in a vacuum chamber

Alpine Quantum’s ion trap works like a quantum processor.Credit: Alpine Quantum Technologies

Alpine Quantum Technologies in Innsbruck, Austria, was spun off from the University of Innsbruck and the Austrian Academy of Sciences in Vienna in 2018.

Quantum computers promise to outperform their conventional counterparts in a range of demanding tasks by exploiting some strange properties of the atomic world. Whether the challenge is to design new materials, optimize delivery logistics or develop drugs, these machines should in principle be able to perform calculations much faster than classical devices.

Alpine Quantum Technologies (AQT), a start-up in Innsbruck, Austria, which spun out of the University of Innsbruck and the Austrian Academy of Sciences in Vienna, is building computers that have the potential to do all this and more. These computers are based on ion traps, which consist of arrays of single ions held in vacuum by electric fields and manipulated by extremely short laser pulses. AQT’s approach to this technology is among the most advanced in the world. But the company’s researchers are clear that it will not be easy to realize a full-fledged quantum computer.

Unlike some competing companies, which try to offer a combination of hardware, software and applications, AQT focuses solely on hardware. It sells individual components – such as ion traps, laser stabilizers and associated electronics – to other researchers investigating quantum phenomena, while developing its own ion-precipitating quantum computers. (Another finalist in The Spinoff Prize 2023, Parity Quantum Computing, by contrast, sells blueprints for quantum computers that can be applied to all kinds of hardware, not just ion traps.)

Strange and delicate

Quantum computers derive their unique capabilities from counterintuitive phenomena. While units of data called bits in a standard digital unit assume the values ​​of either 0 or 1, quantum bits – or qubits – can exist in what is called a superposition of 0 and 1 at the same time. In addition, multiple qubits can be entangled so that their states are dependent on each other in a way that is not possible with everyday classical objects – those larger than a few atoms. Taken together, superposition and entanglement allow a set of qubits to exist in all possible combinations of 0s and 1s simultaneously, providing a potentially huge advantage in processing speed over current classical computers.

But with great power comes great fragility. Quantum states can be destroyed by even the slightest disturbance, including minute amounts of heat or radio wave energy. So while qubits must be manipulated to execute quantum algorithms, they must also remain as isolated as possible from the outside world.

Physicists try to satisfy these conflicting goals by investigating qubits made of a variety of quantum systems, including electric currents in superconducting circuits, the magnetic spin of electrons or atomic nuclei embedded in crystalline solids, and photons traveling around silicon circuits. Each type of qubit has its advantages and disadvantages. The main advantage of ion traps is that they are relatively insensitive to noise. Their disadvantage is the bulky equipment needed, including lasers and associated electronics.

Still, no type of qubit can remain immune to noise as quantum computers scale up, said Thomas Monz, a quantum physicist at the University of Innsbruck and co-founder and CEO of AQT. Increasing the number of qubits, along with the number of processor operations (called gates), makes it more likely that mistakes will creep in during calculations. The solution to this is error correction, which means using multiple physical qubits to represent a single logical bit of data. That way, the value of these qubits can be compared, and the system can clean out any that fall for noise.

But error correction is not cheap. Typically, that multiplies the number of qubits required for a given calculation by several orders of magnitude, meaning, Monz says, that at least a million qubits will likely be needed to compete with classical computers. That’s a far cry from the few dozen typical of the most advanced quantum computers.

Slowly do it

AQT arose from almost a quarter of a century of research into ion trap quantum calculations carried out at the University of Innsbruck by physicists Peter Zoller and Rainer Blatt, and later Monz. As Monz recalls, researchers at other institutions often approached the group to ask if they could purchase ion traps and related accessories. Wanting to help but realizing, as Monz puts it, that he could not use the Austrian taxpayers’ money to satisfy the requests, he began to draw up a financial plan. In 2018, the trio set up AQT to sell the coveted components while ultimately aiming to build their own full-scale computer.

For Lieven Vandersypen, who is developing rival “quantum dot” qubits at Delft University of Technology in the Netherlands, this dual approach makes sense. Selling the components “generates some income and puts them in a commercial mode of operation,” he says, while allowing the researchers to work on the “long-term challenges of a large-scale quantum computing system.”

The long-term work bears fruit. In 2020, Monz, Blatt, and their colleagues reported how to fix a previously uncorrected type of error that can plague quantum computing—the loss of a qubit in a “register”1. They followed this up by demonstrating a complete set of gates that could be used to process qubits in a universal quantum computer2. This device is capable of all kinds of calculations, whether quantum or classical. They did it by entangling two error-corrected logic quantum bits, the values ​​of which were distributed over seven ions (see ‘ion trap quantum processor’).

Ion trap quantum processor

Credit: Alisdair MacDonald

Despite this encouraging progress, the AQT team is determined to keep expectations in check. The company has successfully demonstrated several universal quantum computers, installed in industry-standard 19-inch racks, used for computer servers. Monz admits that manufacturers of quantum computers often brag about the number of qubits in their processors – US tech giant IBM, for example, has announced plans for a computer with around 1,000 superconducting qubits this year. But Monz doesn’t want to be in the numbers game. What really matters, he says, is the quality of the qubits. – If you want to make schnapps, it doesn’t matter if you have 10 or 100 rotten apples, he says. “You must start with 10 good apples.”

The current version of AQT’s computer exists in two forms: a system that has two error-corrected high-quality qubits, or a system with ten times as many lower-quality ones. Monz expects most customers to choose the latter, which he says may still be appropriate for tasks where errors are not particularly problematic, such as optimizing financial portfolios or investigating logistics issues. “There will be this transition where everyone will initially work with flawed qubits and find use cases,” he says. “Only later, when society has access to abundant error-corrected qubits, will we be able to achieve ultra-high-precision quantum computations.”

AQT has 20 employees and generated approximately €1 million ($1.1 million) in sales in 2021, having sold its ion trap components to academic and industrial research groups in Europe, North America and Asia. It also offers access to its quantum computers either remotely via the cloud or by installing them in customers’ labs. So far, however, no complete working systems have been sold.

AQT’s director of technology, Juris Ulmanis, explains that he and his colleagues are careful not to overpromise, making sure the quantum bits and gates that make up their processors are as robust as possible before the devices scale up. “You have to excite people and inspire them, but at the same time be realistic about what’s possible,” says Ulmanis.

Such cautious assessments also come from outside. Vandersypen, for example, points out that AQT’s strategy may have a flaw: selling its components could give competitors a heads-up on the company’s technology.

Monz acknowledges this concern, explaining that he and his colleagues do not sell everything they produce. They actually keep at least some of their secret ingredients off the shelves. “There’s still a lot of ‘special sauce’ left,” he says.

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