New quantum computing hardware marks a major advance in the race to quantum advantage.Princeton University/Matt Raspanti
Researchers from the United States have confirmed that their new qubit lasts for over 1 millisecond — three times longer than the best ever reported in a lab setting. It’s also nearly fifteen times longer than industry-standard processors.
The milestone is achieved by researchers from Princeton University. Researchers claimed that the new qubit design is similar to those already used by leading companies like Google and IBM, and could easily be slotted into existing processors.
“The real challenge, the thing that stops us from having useful quantum computers today, is that you build a qubit and the information just doesn’t last very long,” said Andrew Houck, leader of a federally funded national quantum research center, Princeton’s dean of engineering, and co-principal investigator on the paper.
“This is the next big jump forward.”
The researchers built a fully functioning quantum chip based on this qubit to validate its performance, clearing one of the key obstacles to efficient error correction and scalability for industrial systems.
Houck underlined that swapping Princeton’s components into Google’s best quantum processor would enable it to work 1,000 times better.
The benefits of the Princeton qubit grow exponentially as system size grows, so adding more qubits would bring even greater benefit.
Two-pronged approach
The research team revealed that they took a two-pronged approach to redesigning the qubit. First, they used a metal called tantalum to help the fragile circuits preserve energy. Second, they replaced the traditional sapphire substrate with high-quality silicon, the standard material of the computing industry.
To grow tantalum directly on silicon, the team had to overcome a number of technical challenges related to the materials’ intrinsic properties. But ultimately they prevailed, unlocking the deep potential of this combination.
Quantum computers have shown the potential to solve problems that cannot be addressed with conventional computers. But current versions are still in early stages of development and remain limited.
This is mainly because the basic component in quantum computers, the qubit, fails before systems can run useful calculations. Extending the qubit’s lifetime, called coherence time, is essential for enabling quantum computers to perform complex operations. The Princeton qubit marks the largest single advance in coherence time in more than a decade, according to a press release.
The team also revealed that while engineers are pursuing a range of technologies to develop qubits, the Princeton version relies on a type of circuit called a transmon qubit. Transmon qubits, used in efforts by companies including Google and IBM, are superconducting circuits that run at extremely low temperatures. Their advantages include a relatively high tolerance for outside interference and compatibility with current electronics manufacturing.
But the coherence time of transmon qubits has proven extremely hard to extend. Recent work from Google showed that the major limitation faced in improving their latest processor comes down to the material quality of the qubits, as per the release.
Published in the Nature, the paper reveals that the research team achieved materials improvements without any modifications to the qubit architecture, allowing us to readily incorporate standard quantum control gates.
“We demonstrate single-qubit gates with 99.994% fidelity. The tantalum-on-silicon platform comprises a simple material stack that can potentially be fabricated at the wafer scale and therefore can be readily translated to large-scale quantum processors,” said researchers.
