From predicting climate patterns to finding new drugs that treat diseases, advanced computing technologies could transform how we tackle today’s most pressing issues.

Quantum computers, in particular, stand out for their potential to solve complex problems far faster than conventional computers.

In classical computers that many of us use daily, information processing is made possible by units of data called bits. These bits can hold a value of either zero or one, whereas quantum bits (qubits) can exist as both states at once, like a spinning coin before landing on heads or tails.

This unique trait allows quantum computers to process information simultaneously rather than sequentially, potentially speeding up complicated calculations.

However, several challenges stand in the way of widespread adoption of quantum computers. To move a step closer to practical quantum devices, NTU researchers are investigating the tiny particles that could be used as qubits.

Keeping qubits spinning

A qubit’s lifetime is influenced by environmental factors and the materials in which they are placed. A key challenge in building quantum computers is not just producing qubits but keeping them in their quantum states long enough to perform complex computations.

Researchers like Assoc Prof Bent Weber from NTU’s School of Physical & Mathematical Sciences are using electrons as qubits and finding ways to prolong their lifetimes in exotic materials. The electron’s “spin” – a property akin to the particle rotating along its axis – can be used to encode a qubit.

Like electrical switches, electrons can be in an “on” state when spinning upwards or “off” when spinning downwards, or even in multiple states at once. This property allows them to function as qubits. However, most spin qubits have very short lifetimes as they are easily corrupted by environmental disturbances, which is often why they require ultralow temperatures to work.

To address this, Assoc Prof Weber explains that layering different semiconductor materials can help keep qubits stable for longer. Some of these materials are “topological insulators”, which are atomically-thin ultraflat 2D materials that do not conduct electricity inside but allow electrons to flow along their outer edges.

“Along the edges of these materials, electrons can only move left or right, and which way they spin is tied to that direction. Electrons spinning in one direction do not couple to electrons spinning the other way,” explains Assoc Prof Weber.

Using this unique property, his team hopes to engineer stable qubits with longer lifetimes. If successful, these stable qubits will allow for more powerful and less error-prone quantum computing in the future.

Coaxing light link-ups

While electrons often require ultralow temperatures to maintain stable quantum effects, photons – or light particles –could offer a more practical alternative, as they can function as qubits at room temperature. However, to enable more efficient simultaneous computing, photons must be linked to one another so that changes in the properties of one also affect the other.

Two linked photons present four possible states: 0-0, 0-1, 1-0 and 1-1. “We are not just manipulating one qubit at a time but all four possibilities simultaneously,” says Prof Gao Weibo from NTU’s School of Electrical & Electronic Engineering and School of Physical & Mathematical Sciences.

“With just 300 linked qubits, you could work with more possible states than the number of atoms in the known universe.”

To enable such large-scale quantum processing, Prof Gao and his team are exploring integrated photonics platforms. Their approach involves stacking multiple ultrathin layers of semiconducting materials at different angles, creating a compact structure that promotes strong interactions between photons.

Prof Zhang Baile of the School of Physical & Mathematical Sciences says that specially designed crystal structures with light-guiding channels can enhance light coupling. These structures protect light from scattering, much like highway barriers that keep vehicles from veering off course.

“Information travelling through multiple channels would not get mixed up. This kind of robustness is essential for building stable quantum photonic circuits,” says Prof Zhang.

The best of both worlds

As electrons are vulnerable to noise that causes them to lose energy, and photons require carefully controlled environments for interacting, an alternative qubits platform known as polaritons may offer a solution. Polaritons are hybrid particles that are part light and part matter.

“The light part of polaritons enables quantum information to travel rapidly and coherently across a chip with less energy loss, while their matter part provides strong and controllable interactions between particles,” explains Nanyang Asst Prof Su Rui from the School of Physical & Mathematical Sciences and School of Electrical & Electronic Engineering.

To investigate polariton-based quantum functionalities at room temperature, his research group used an echo chamber-like structure that bounces photons back and forth to strengthen their interactions, layered with a liquid crystal that allows precise control over how polaritons spin.

These controlled interactions are crucial for computing tasks such as complex, multi-component system simulations –problems that are difficult to solve using classical computers. “Polariton systems present a promising foundation for large-scale, complex quantum simulation and computing that is fast, energy-efficient and works at room temperature,” says Asst Prof Su.

By devising ways to control the spin properties of polaritons, the team hopes to build the next generation of quantum devices that can function under everyday conditions and tolerate external noise, paving the way for more stable and practically usable quantum computers.

The article appeared first in NTU's research & innovation magazine Pushing Frontiers (issue #26, May 2026).