Scientists have finally figured out how to read ultra-secure Majorana qubits—bringing robust quantum computing a big step closer.
“This is a crucial advance,” says Ramón Aguado, a CSIC researcher at the Madrid Institute of Materials Science (ICMM) and co author of the study. He explains that the team has shown it is possible to retrieve information stored in Majorana qubits using a technique known as quantum capacitance. According to Aguado, this method works as “a global probe sensitive to the overall state of the system,” allowing researchers to detect properties that were previously out of reach.
Why Topological Qubits Are So Hard to Measure
Aguado compares topological qubits to “safe boxes for quantum information.” Instead of keeping data in a single, fixed location, these qubits spread information across two linked quantum states called Majorana zero modes. Because the information is distributed in this non local way, it is naturally shielded from small, local disturbances that typically disrupt fragile quantum systems.
This built in protection is what makes topological qubits so appealing for quantum computing. “They are inherently robust against local noise that produces decoherence, since to corrupt the information, a failure would have to affect the system globally,” Aguado explains. But that same strength has created a major experimental challenge. If the information does not sit in one specific place, how can scientists actually detect or measure it? As Aguado puts it, “this same virtue had become their experimental Achilles’ heel: how do you “read” or “detect” a property that doesn’t reside at any specific point?”
Building a Kitaev Minimal Chain
To solve this problem, the researchers constructed a carefully designed nanostructure known as a Kitaev minimal chain. Aguado likens the process to assembling Lego pieces. The device consists of two semiconductor quantum dots connected through a superconductor, forming a small but precisely controlled system.
This bottom-up approach marks a shift from earlier experiments that relied on more complex material combinations without the same level of control. “Instead of acting blindly on a combination of materials, as in previous experiments, we create it bottom-up and are able to generate Majorana modes in a controlled manner, which is in fact the main idea of our QuKit project,” Aguado says.
Real-Time Detection of Majorana Parity
After creating the minimal Kitaev chain, the team applied the quantum capacitance probe. For the first time, they were able to determine in real time, and in a single measurement, whether the combined quantum state of the two Majorana modes was even or odd. In simple terms, they could tell whether the qubit was in a filled or empty state, which forms the basis of how it stores information.
“The experiment elegantly confirms the protection principle: while local charge measurements are blind to this information, the global probe reveals it clearly,” says researcher Gorm Steffensen of ICMM CSIC. The results show that although conventional measurements cannot see the hidden information, a system-wide probe can successfully uncover it.
Millisecond Coherence and Random Parity Jumps
The experiment also revealed “random parity jumps,” another important finding. By observing these events, the researchers measured “parity coherence exceeding one millisecond,” a timescale that is considered highly promising for future operations involving topological qubits based on Majorana modes.
International Collaboration Advances Quantum Computing
The work combines an innovative experimental approach developed mainly at Delft University of Technology with theoretical analysis from ICMM CSIC. The authors emphasize that the theoretical contribution was “crucial for understanding this highly sophisticated experiment,” highlighting the collaborative effort behind this advance in quantum computing.
Reference: “Single-shot parity readout of a minimal Kitaev chain” by Nick van Loo, Francesco Zatelli, Gorm O. Steffensen, Bart Roovers, Guanzhong Wang, Thomas Van Caekenberghe, Alberto Bordin, David van Driel, Yining Zhang, Wietze D. Huisman, Ghada Badawy, Erik P. A. M. Bakkers, Grzegorz P. Mazur, Ramón Aguado and Leo P. Kouwenhoven, 11 February 2026, Nature.
DOI: 10.1038/s41586-025-09927-7
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