Scientists have developed a new manufacturing method to create superconducting quantum bits (qubits) that can remain coherent three times longer than current state-of-the-art systems in the lab. This makes it possible to perform more powerful quantum computing operations.
The new technology, described in a study published Nov. 5 in the journal Nature, relies on the use of a rare earth element called tantalum. It belongs to the ‘transition metals’ group of the periodic table and is ‘grown’ by building metal films atom by atom on minerals such as tantalite and silicon.
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“The real challenge, and what’s holding us back from today’s useful quantum computers, is that when we build qubits, the information doesn’t persist for very long,” Andrew Houck, dean of engineering at Princeton University and co-principal investigator of the study, said in the study. “This is the next big leap forward.”
Decoherence and imperfections
Coherence in quantum computing is a measure of how long a qubit can remain in a wave state. When a qubit decoheals, information is lost. This makes maintaining coherence one of the biggest challenges in quantum computing.
Scientists have spent several years using tantalum as a material to develop qubits. When superconducting materials such as tantalum are cooled to near absolute zero, circuits built within them can operate with almost no resistance. This allows for faster quantum operations, but the speed and number of operations are fundamentally limited by the amount of time a qubit can maintain an information state.
The advantage of tantalum is that it is easy to scrub away contaminants that can cause imperfections in the manufacturing process. Imperfections can lead to faster decohering of affected qubits. Tantalum’s inert elasticity protects it from certain state changes associated with corrosion and molecular displacement. It does not absorb acids even when soaked. This makes it a perfect candidate for use as a superconducting material for quantum computing, the scientists said in the study.
But keeping qubit materials defect-free is only half the battle. Manufacturing a quantum processor requires both a base layer material and a substrate. In previous experiments, scientists achieved cutting-edge quantum computing results using processors built with tantalum-based layers and sapphire substrates. Although these experiments were successful, the coherence speed was still less than 1 ms.
The Princeton University team replaced the sapphire substrates used in these experiments with high-resistivity silicon developed using proprietary technology. According to the study, a system with around 48 qubits achieved a coherency rate as high as 1.68 milliseconds, the highest ever for a superconducting qubit.
The new qubit design is similar to those used in superconducting quantum processors developed by major companies such as Google and IBM. Houck added: “If you replace the Princeton components with Google’s best quantum processor, Willow, it will run 1,000 times better.”
What this means for the quantum computing industry remains unclear. Scientists have significantly improved the coherence rate of qubits, but challenges remain. Chief among them is the availability of tantalum. As of 2025, tantalum is considered a rare metal, with most mining occurring in Africa.
New qubits offer significant increases in coherence, but must be tested at larger sizes using wafer-scale chipsets before being integrated into quantum computers being deployed commercially today.
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