Researchers find a way to shield quantum information from ‘noise’

In a study published in Nature Communications, scientists have shown how certain quantum states can maintain their critical information even when disturbed by environmental noise.

Why this research matters

• More Reliable Quantum Technology — This breakthrough could lead to more stable quantum computers and networks, making future technology faster, more secure, and widely accessible.
• Better Medical Imaging & AI — The ability to preserve quantum information can enhance medical imaging techniques and improve AI-driven diagnostics, leading to better healthcare solutions.
• Stronger Data Security — Quantum networks protected from noise could provide ultra-secure communication, safeguarding personal and financial data from cyber threats.

“What we’ve found is that topology is a powerful resource for information encoding in the presence of noise,” says Professor Andrew Forbes from the Wits School of Physics.

Quantum entanglement is the invisible connection between particles that allows them to communicate instantly, no matter how far apart they are. This principle is the subject of popular science and the cornerstone of modern quantum technologies. However, it has famously been rejected by Einstein as “spooky action at a distance.”

Unfortunately, quantum entangled states are notoriously fragile, decaying when they experience a perturbation, such as background and stray light, noisy detectors, lost photons and other sources of “white” noise, common effects in real-world quantum systems that can break the connection between the particles, rendering their entangled link useless.

To overcome this, many strategies have been put forward to try and preserve the entanglement, but so far with very limited success. The Wits team have shown that this approach can be manipulated, allowing the entanglement to remain fragile and instead preserve the quantum information.

“We are carefully engineering the quantum wave function — a mathematical description that captures all possible states of a quantum system — to preserve quantum information that remains stable even when the underlying quantum connections start to break down,” says Forbes.

The researchers discovered that by engineering quantum states with specific topological properties, they could preserve quantum information even when the entanglement between particles begins to break down.

“What we’ve found is that topology is a powerful resource for information encoding in the presence of noise. It has a large encoding alphabet that is complete immune to the noise so long as just some entanglement persists.”

Prof. Robert de Mello Koch explains that this manipulation of the quantum waveform topology can be seen as a form of “digitisation of quantum information” made possible by the discrete nature of the topological observables, which only take on integer values, such as -2, -1, 1 and 2.

“Discrete signals are always more robust against the effects of noise. This follows because for discrete signals the noise must be able to flip the signal between two discrete states before any effect is registered.”

The team believe that just as digital technology has enabled successful classical computation and communication, so too will digital quantum signals allow successful quantum computation and communication under realistic conditions without the need for compensating strategies.

“This breakthrough could be used to overcome noise in quantum computers as well as global quantum networks, for the next generation of quantum technologies. It can be especially valuable in creating advanced medical imaging technologies and more powerful artificial intelligence systems harnessing entanglement,” says Forbes.