Quantum computers promise to tackle problems that are unsolvable for today’s machines, but their basic units (qubits) are incredibly fragile. Even a tiny disturbance can wipe out the entire delicate quantum information they hold.
Now, a team led by Pan Jianwei at the University of Science and Technology of China has taken an important step toward overcoming this challenge.
In their latest paper, they report the creation of a quantum block that stays intact even when shaken. This feat has been achieved using a powerful programmable superconducting quantum processor, Zuchongzhi 2.
The significance of an unshakable quantum block
To grasp why this work is important, imagine trying to keep a soap bubble intact while walking through a crowded room. That’s roughly how hard it is to preserve quantum information.
Traditional error-correction methods help, but they are complex and require many extra qubits. Pan’s team took a different approach by turning to topology, a field of mathematics that studies global features of shapes.
In topological phases of matter, certain properties become surprisingly robust because they depend on these global features rather than fragile local details. Researchers have already explored topological materials whose protected states appear along their edges.
However, the Chinese team aimed for something more elusive: higher-order topological phases, where the protected states gather in even smaller regions, such as corners. These “corner modes” are not literally unbreakable, but they can be more resistant to disturbance than ordinary quantum states.
What made the project especially challenging is that the team focused on non-equilibrium versions of these phases—systems that are constantly evolving or being driven by external forces instead of settling into a steady state.
Such phases do not naturally occur in materials, and scientists have lacked reliable tools to test or observe them.
Achieving high-order topological behavior
To solve this, the researchers used part of their Zuchongzhi 2 superconducting processor, arranging a 6×6 grid of qubits to act as a programmable quantum simulator.
Since this processor can be reconfigured like a quantum version of a central processing unit, the team could design precise interactions between qubits that mimic a synthetic material with higher-order topological behaviour.
They then applied a sequence of controlled operations to produce the non-equilibrium topological phases they sought. Detecting these phases required a new strategy: instead of looking at static properties, they measured how the qubits’ behaviour evolved.
By tracking these dynamics, they identified the characteristic signatures of corner modes, confirming that both equilibrium and non-equilibrium higher-order topological phases had been successfully simulated.
“In this study, we implemented both equilibrium and non-equilibrium higher-order topological phases using a two-dimensional programmable superconducting quantum processor,” the study authors note.
In short, the team used a quantum processor to build and examine a form of matter that does not naturally occur, and demonstrated that it hosts small, topologically protected corner states that behave differently from ordinary qubit arrangements.
Future possibilities and challenges
The quantum block created by the researchers represents the first experimental demonstration of non-equilibrium higher-order topological phases on a programmable quantum processor.
It shows that even today’s noisy intermediate-scale quantum processors can be used as versatile platforms to create and study exotic states of matter, offering a powerful new tool for the future of quantum science.
Although this work does not yet create a fully error-proof qubit, it shows a promising direction—using topology to design quantum states that are naturally less sensitive to certain disturbances.
If such protected modes can be engineered into future hardware, they could form the basis of more reliable quantum memory or logic units. That, in turn, could help unlock large-scale quantum computing for tasks such as complex simulations, advanced materials design, or AI research.
However, important challenges remain. For instance, the protected corner states demonstrated here exist within a carefully controlled, simulated environment rather than a physical material. Their stability under real-world noise still needs thorough testing, and the method will need to be scaled up far beyond a 6×6 qubit array to be useful in practical machines.
Further steps would include exploring interactions between qubits, studying more complex topological phases, and applying the approach to investigate custom-designed quantum materials—both in and out of equilibrium.
The study is published in the journal Science.