Quantum computing breakthrough could happen with just hundreds, not millions, of qubits using new error-correction system

Quantum computers that are more powerful than the fastest supercomputers could be closer than experts have predicted, researchers from startup Nord Quantique argue. 

That's because the company has built an individual error-correcting physical qubit that could dramatically cut the number of qubits needed to achieve quantum advantage (which is where quantum computers are genuinely useful). 

Eventually, this could lead to a machine that achieves quantum supremacy — where a quantum computer is more powerful than classical computers.

Unlike classical bits that encode data as 1 or 0, qubits rely on the laws of quantum mechanics to achieve "coherence" and encode data as a superposition of 1 or 0 — meaning data is encoded in both states simultaneously. 

In quantum computers, multiple qubits can be stitched together through quantum entanglement — where qubits can share the same information no matter how far they are separated over time or space — to process calculations in parallel, while classical computers can only process calculations in sequence.   

But qubits are "noisy," meaning they are highly prone to interference from their environment, such as changes in temperature, which leads to high error rates. For that reason, they often need to be cooled to near absolute zero, but even then they can still fall into "decoherence" midway through calculations and fail due to external factors. 

Related: How could this new type of room-temperature qubit usher in the next phase of quantum computing?