A clever quantum trick brings practical quantum computers closer - ScienceDaily

Science News from research organizations A clever quantum trick brings practical quantum computers closer Date: February 6, 2026 Source: ETH Zurich Summary: Quantum computers struggle because their qubits are incredibly easy to disrupt, especially during calculations. A new experiment shows how to perform quantum operations while continuously fixing errors, rather than pausing protection to compute.

The team used a method called lattice surgery to split a protected qubit into two entangled ones without losing control. This breakthrough moves quantum machines closer to scaling up into something truly powerful. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY Quantum computers can protect fragile qubits while storing information, but doing calculations without introducing errors has been a major challenge. Researchers have now shown that “lattice surgery” can safely manipulate qubits mid-operation, bringing practical quantum computing a step closer. Credit: Shutterstock Quantum computers have the potential to transform fields ranging from materials science to cryptography, but today they remain extremely difficult to build and operate. One of the biggest challenges comes from decoherence, a process that introduces errors into quantum systems. These errors usually take the form of bit flips or phase flips. A bit flip occurs when a qubit unexpectedly switches between '0' and '1'. A phase flip happens when the phase of a quantum superposition suddenly reverses, changing from positive to negative. Because these changes can happen at random, even a single error can disrupt a calculation. Preventing that disruption is one of the central problems facing quantum engineers.

Protecting Information With Logical Qubits To reduce these errors, researchers combine many physical qubits into a single logical qubit and apply continuous error correction. This strategy helps preserve quantum information over time, making storage relatively stable. But storing information is only part of the task. To run a quantum algorithm, qubits must be actively manipulated using quantum gates, which are the basic operations that power quantum computation. Applying those operations without introducing new errors has proven far more difficult than simply keeping qubits stable at rest. A New Way to Compute While Fixing Errors A team led by D-PHYS Professor Andreas Wallraff has now demonstrated a method that tackles this problem directly. Working with researchers from the Paul Scherrer Institute (PSI) and theorists led by Professor Markus Müller at RWTH Aachen University and Forschungszentrum Jülich, the group showed how to perform quantum operations between superconducting logical qubits while correcting errors at the same time. Their findings were recently published in Nature Physics. The work marks an important advance toward fault tolerant quantum computing, where calculations can proceed without being derailed by constant errors.

Why Quantum Error Correction Is Different Error correction in classical computers relies on copying information. Multiple identical bits can be stored, checked later, and compared. If one flips, a majority vote reveals the correct value. That approach does not work in quantum systems. "With qubits, things are a lot more complicated," says Dr. Ilya Besedin, a postdoctoral researcher in Wallraff's group and co-leading author of the study alongside PhD student Michael Kerschbaum. Quantum information cannot be copied or cloned. Instead, it must be distributed across entangled qubits. On top of that, quantum systems suffer from phase flip errors, which have no equivalent in classical computing and require their own correction methods.

Error Correction With Surface Codes One widely used solution involves surface codes. In this approach, the information of a single qubit is spread across several physical data qubits. Error detection relies on repeated measurements of stabilizers, which work alongside the data qubits to form the logical qubit. These stabilizers are monitored using additional qubits connected to the data qubits. Measuring them reveals whether a bit flip or phase flip has occurred between checks. Z-type stabilizers detect changes in bit value, while X-type stabilizers detect phase changes. Importantly, the data qubits themselves are never directly measured, allowing them to safely store the corrected quantum state. The Challenge of Performing Logical Operations The process becomes more complex when researchers want to apply a logical operation such as a controlled-NOT gate between two logical qubits. Errors can occur during the operation itself, and those errors must also be corrected. "Performing a logical operation in this fault-tolerant way would be relatively easy if we could move our qubits around and connect them arbitrarily to each other," says Kerschbaum. In superconducting quantum processors, however, qubits are fixed in place. Only neighboring qubits can interact, which limits how operations can be carried out. Splitting the Square With Lattice Surgery To work within those constraints, the team turned to a method known as lattice surgery. In their experiment, the researchers began with a single logical qubit encoded across seventeen physical qubits. The data qubits and stabilizers were arranged in a roughly square pattern. Over several cycles, stabilizers were measured every 1.66 microseconds to correct both bit flips and phase flips. At a key moment, three data qubits running through the center of the square were measured. This step effectively divided the surface code into two separate halves. At the same time, measurements of the X-type stabilizers were paused. "The end result of this operation was that we had two logical qubits entangled with each other," explains Besedin. During the splitting process, bit flip errors continued to be corrected. Afterward, bit flip error correction resumed independently on each half. While this operation does not yet produce a controlled-NOT gate on its own, it can be combined with additional splitting and merging steps to create one. A First for Superconducting Qubits "One could say that the lattice surgery operation is the operation, and all the others can be constructed from it," says Besedin. He adds, "To the best of our knowledge, this is the first time lattice surgery has been performed on superconducting qubits," he adds, "and we still have some way to go. For instance, 41 physical qubits would be required to make the splitting operation on one logical qubit stable against phase flips too. Nonetheless, this demonstration of lattice surgery on superconducting qubits marks an important step towards the ambitious goal of building useful quantum computers with thousands of qubits. RELATED TOPICS Matter & Energy Engineering and Construction Quantum Physics Physics Nanotechnology Computers & Math Computers and Internet Hacking Computer Programming Encryption RELATED TERMS Quantum computer Schrödinger's cat Quantum entanglement Science Computing Introduction to quantum mechanics Robotic surgery Quantum dot Story Source: Materials provided by ETH Zurich. Note: Content may be edited for style and length. Journal References: Ilya Besedin, Michael Kerschbaum, Jonathan Knoll, Ian Hesner, Lukas Bödeker, Luis Colmenarez, Luca Hofele, Nathan Lacroix, Christoph Hellings, François Swiadek, Alexander Flasby, Mohsen Bahrami Panah, Dante Colao Zanuz, Markus Müller, Andreas Wallraff. Lattice surgery realized on two distance-three repetition codes with superconducting qubits. Nature Physics, 2026; DOI: 10.1038/s41567-025-03090-6 Sebastian Krinner, Nathan Lacroix, Ants Remm, Agustin Di Paolo, Elie Genois, Catherine Leroux, Christoph Hellings, Stefania Lazar, Francois Swiadek, Johannes Herrmann, Graham J. Norris, Christian Kraglund Andersen, Markus Müller, Alexandre Blais, Christopher Eichler, Andreas Wallraff. Realizing repeated quantum error correction in a distance-three surface code. Nature, 2022; 605 (7911): 669 DOI: 10.1038/s41586-022-04566-8 Cite This Page: MLA APA Chicago ETH Zurich. "A clever quantum trick brings practical quantum computers closer." ScienceDaily. ScienceDaily, 6 February 2026. . ETH Zurich. (2026, February 6). A clever quantum trick brings practical quantum computers closer. ScienceDaily. Retrieved February 6, 2026 from www.sciencedaily.com/releases/2026/02/260206012208.htm ETH Zurich. "A clever quantum trick brings practical quantum computers closer." ScienceDaily. www.sciencedaily.com/releases/2026/02/260206012208.htm (accessed February 6, 2026). Explore More from ScienceDaily RELATED STORIES Caltech Breakthrough Makes Quantum Memory Last 30 Times Longer Aug. 27, 2025 — While superconducting qubits are great at fast calculations, they struggle to store information for long periods. A team at Caltech has now developed a clever solution: converting quantum information ... Quantum: Calculating Error-Free More Easily With Two Codes Jan. 24, 2025 — Various methods are used to correct errors in quantum computers. Not all operations can be implemented equally well with different correction codes. Therefore, a research team has developed a method ...

Advancing Modular Quantum Information Processing Aug. 15, 2024 — A team of physicists envisions a modular system for scaling quantum processors with a flexible way of linking qubits over long distances to enable them to work in concert to perform quantum ...

Breakthrough May Clear Major Hurdle for Quantum Computers June 18, 2024 — The potential of quantum computers is currently thwarted by a trade-off problem. Quantum systems that can carry out complex operations are less tolerant to errors and noise, while systems that are ... Understanding the Tantalizing Benefits of Tantalum for Improved Quantum Processors May 31, 2023 — Researchers working to improve the performance of superconducting qubits, the foundation of quantum computers, have been experimenting using different base materials in an effort to increase the ... All-Nitride Superconducting Qubit Made on a Silicon Substrate Sep. 20, 2021 — Researchers have succeeded in developing an all-nitride superconducting qubit using epitaxial growth on a silicon substrate that does not use aluminum as the conductive material. This qubit uses ... TRENDING AT SCITECHDAILY.com Low-Dose THC May Help Protect the Gut and Liver in HIV One Overlooked Gene May Shape Nearly All Alzheimer’s Risk New Treatment Wipes Out Cancer Cells Without Harming Healthy Tissue A Tiny Dinosaur With a Weird Skull Is Rewriting Evolution