Princeton engineers have created a superconducting qubit that is still stable for 3 times longer than the strongest designs available today. This improvement represents a very important move toward constructing quantum computers that may operate reliably.
“The true challenge, the thing that stops us from having useful quantum computers today, is that you simply construct a qubit and the data 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. “That is the following big jump forward.”
In a Nov. 5 article published in Nature, the Princeton team reported that their qubit maintains coherence for greater than 1 millisecond. This performance is triple the longest lifetime documented in laboratory experiments and nearly fifteen times greater than the usual utilized in industrial quantum processors. To verify the result, the team constructed a functioning quantum chip based on the brand new qubit, demonstrating that the design can support error correction and scale toward larger systems.
The researchers noted that their qubit is compatible with the architectures utilized by major firms similar to Google and IBM. In keeping with their evaluation, replacing key components in Google’s Willow processor with Princeton’s approach could increase its performance by an element of 1,000. Houck added that as quantum systems incorporate more qubits, the benefits of this design increase much more rapidly.
Why Higher Qubits Matter for Quantum Computing
Quantum computers show promise for solving problems that traditional computers cannot address. Yet their current abilities remain limited because qubits lose their information before complex calculations will be accomplished. Extending coherence time is subsequently essential for constructing practical quantum hardware. Princeton’s improvement represents the biggest single gain in coherence time in greater than ten years.
Many labs are pursuing different qubit technologies, but Princeton’s design builds on a widely used approach referred to as the transmon qubit. Transmons, which operate as superconducting circuits held at extremely low temperatures, are known for being proof against environmental interference and compatible with modern manufacturing tools.
Despite these strengths, increasing the coherence time of transmon qubits has proven difficult. Recent results from Google showed that material defects now pose the essential barrier to improving their newest processor.
Tantalum and Silicon: A Latest Materials Strategy
The Princeton team developed a two-part strategy to deal with these material challenges. First, they incorporated tantalum, a metal known for helping delicate circuits retain energy. Second, they replaced the usual sapphire substrate with high-purity silicon, a cloth foundational to the computing industry. Growing tantalum directly on silicon required solving several technical problems related to how the 2 materials interact, however the researchers succeeded and uncovered significant benefits in the method.
Nathalie de Leon, co-director of Princeton’s Quantum Initiative and co-principal investigator of the project, said the tantalum-silicon design not only performs higher than previous approaches but can also be simpler to fabricate at scale. “Our results are really pushing the cutting-edge,” she said.
Michel Devoret, chief scientist for hardware at Google Quantum AI, which provided partial funding, described the issue of extending the lifetime of quantum circuits. He noted that the challenge had turn into a “graveyard” of attempted solutions. “Nathalie really had the center to pursue this strategy and make it work,” said Devoret, the 2025 Nobel Prize winner in physics.
The project received primary funding from the U.S. Department of Energy National Quantum Information Science Research Centers and the Co-design Center for Quantum Advantage (C2QA), a middle directed by Houck from 2021 to 2025 and where he now serves as chief scientist. The paper lists postdoctoral researcher Faranak Bahrami and graduate student Matthew P. Bland as co-lead authors.
How Tantalum Improves Qubit Stability
Houck, the Anthony H.P. Lee ’79 P11 P14 Professor of Electrical and Computer Engineering, explained that a quantum computer’s capability depends upon two essential aspects. One is the whole variety of qubits that will be linked together. The opposite is what number of operations each qubit can complete before errors accumulate. Improving the sturdiness of a single qubit strengthens each of those aspects. Longer coherence time directly supports scaling and more reliable error correction.
Energy loss is essentially the most common reason behind failure in these systems. Microscopic surface defects within the metal can trap energy and disrupt the qubit during calculations. These disruptions multiply as more qubits are added. Tantalum is particularly helpful since it typically comprises fewer of those defects than metals like aluminum. With fewer defects, the system produces fewer errors and simplifies the technique of correcting those that remain.
Houck and de Leon introduced tantalum for superconducting chips in 2021 with help from Princeton chemist Robert Cava, the Russell Wellman Moore Professor of Chemistry. Cava, who makes a speciality of superconducting materials, became serious about the issue after hearing one in every of de Leon’s talks. Their conversations eventually led him to suggest tantalum as a promising material. “Then she went and did it,” Cava said. “That is the amazing part.”
Researchers across all three labs followed this concept and built a tantalum-based superconducting circuit on a sapphire substrate. The result showed a big improvement in coherence time, approaching the previous world record.
Bahrami noted that tantalum stands out since it is amazingly durable and may withstand the tough cleansing used to remove contamination during fabrication. “You possibly can put tantalum in acid, and still the properties don’t change,” she said.
Once contaminants were removed, the team evaluated the remaining energy losses. They found that the sapphire substrate was answerable for a lot of the remaining problems. Switching to high-purity silicon eliminated that source of loss, and the mixture of tantalum and silicon, together with refined fabrication techniques, produced one in every of the most important improvements ever achieved in a transmon qubit. Houck described the consequence as “a serious breakthrough on the trail to enabling useful quantum computing.”
Houck added that because the advantages of the design increase exponentially as systems grow, replacing today’s industry-leading qubits with the Princeton version could allow a theoretical 1,000-qubit computer to operate about 1 billion times more effectively.
Silicon-Based Design Supports Industry-Scale Growth
The project draws from three areas of experience. Houck’s group focuses on the design and optimization of superconducting circuits. De Leon’s lab makes a speciality of quantum metrology together with the materials and fabrication methods that determine qubit performance. Cava’s group has spent a long time developing superconducting materials. By combining their strengths, the team produced results that not one of the groups could have achieved individually. Their success has already attracted attention from the quantum industry.
Devoret said collaborations between universities and firms are essential for moving advanced technologies forward. “There may be a fairly harmonious relationship between industry and academic research,” he said. University researchers can investigate the elemental limits of quantum performance, while industry partners apply those findings to large-scale systems.
“We have shown that it’s possible in silicon,” de Leon said. “The incontrovertible fact that we have shown what the critical steps are, and the necessary underlying characteristics that can enable these sorts of coherence times, now makes it pretty easy for anyone who’s working on scaled processors to adopt.”
The paper “Millisecond lifetimes and coherence times in 2D transmon qubits” was published in Nature on Nov. 5. Together with de Leon, Houck, Cava, Bahrami, and Bland, the authors include Jeronimo G.C. Martinez, Paal H. Prestegaard, Basil M. Smitham, Atharv Joshi, Elizabeth Hedrick, Alex Pakpour-Tabrizi, Shashwat Kumar, Apoorv Jindal, Ray D. Chang, Ambrose Yang, Guangming Cheng and Nan Yao. This research received primary support from the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Co-design Center for Quantum Advantage (C2QA), and partial support from Google Quantum AI.