QuTech, a leading quantum research institute, announced the development of a novel quantum chip architecture the Qubit-Array Research Platform for Engineering and Testing (QARPET) designed to streamline testing and scalability for semiconductor spin qubit technologies. The breakthrough platform, described in Nature Electronics, enables high-throughput characterization of hundreds of qubits on a single test chip under realistic quantum-computing conditions.
Semiconductor spin qubits are a promising route toward large-scale quantum processors because of their compatibility with established fabrication approaches and compact footprint. The QARPET platform addresses a key engineering challenge in the field: efficiently evaluating the performance, uniformity, and noise characteristics of qubit arrays as systems grow toward thousands or millions of qubits.
“With such a complex, tightly packed quantum chip, things really start to resemble the traditional semiconductor industry,” said Giordano Scappucci, lead researcher. “Building a large-scale quantum processor is not just a matter of adding more qubits. To make progress, we need to understand how qubits perform statistically, how uniform they are, how noisy they are, and how these properties vary across a chip. This really sets QARPET apart.”
QARPET’s innovative design organizes qubits into a grid of small, repeatable tiles, each containing two spin qubits and a charge sensor. These tiles implement a crossbar control scheme, similar to classical memory architectures, which dramatically reduces the number of control lines needed as the array scales. In its first demonstration, a germanium/silicon-germanium (Ge/SiGe) chip with 23×23 tiles potentially supporting up to 1,058 hole-spin qubits was controlled with only 53 total lines.
“This device reaches a potential density of about two million qubits per square millimetre, which highlights how compact semiconductor spin qubits can be,” Scappucci added. “In fact, with the right measurement infrastructure and automation, the chip we built could already allow us to probe more than a thousand qubits in a single cooldown.”
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During system validation, QuTech researchers demonstrated that nearly all tiles could be independently addressed and tuned, enabling extraction of key device metrics such as threshold voltages, charge noise, and dot-formation variability. These insights provide vital feedback for improving material quality and fabrication consistency, enhancing reproducibility for future quantum devices.
“When I designed the first layouts, I honestly did not expect them to work,” said Alberto Tosato, the lead engineer. “The number of crossing electrodes is extremely high. It pushes the limits of nanofabrication, we saw it as a test that would probably fail. So, seeing the device come alive at millikelvin temperatures, that was a very satisfying moment.”
The QARPET architecture is fully compatible with existing semiconductor manufacturing techniques and can be adapted to other spin qubit material systems, including silicon-based platforms. Its modular nature also supports integration with automation and machine-learning-assisted device tuning, positioning QARPET as a foundational tool for scalable quantum technology development.
“Our platform brings together a realistic device architecture with the possibility to extract meaningful statistics from hundreds of qubits in a single experiment,” Scappucci concluded. “Given the complexity and density of this chip, demonstrating that it actually works is an important milestone. It shows that we can already build and study the kind of large qubit arrays that future quantum processors will rely on.”
Source: QuTech