One step away from quantum computing: they reach 99% accuracy

The great handicap of quantum computing is the reliability of the operations, at least for now. For this reason, the great goal of scientists and engineers is to ensure that quantum computers are always accurate. Now we are closer to achieving it.

Three scientific teams from around the world have achieved a major milestone in quantum computing by demonstrating greater than 99% accuracy in silicon-based quantum devices, which opens the way to the creation of practical and scalable quantum computers without errors.

Although quantum computing has great advantages, quantum states are sensitive to external interference, which can cause errors that severely limit the viability of these machines.

But now, the three new studies have shown quantum computer systems with error rates of less than one percent. And what is better, all of these devices are based on silicon, which should make them easier to manufacture with the existing semiconductor business infrastructure.

A team led by University of New South Wales (Australia) achieved 99.95 percent fidelity in a one-qubit system, and 99.37 percent with two operating qubits.

A second team, Delft University of Technology (Netherlands), achieved 99.87 percent with one qubit and a 99.65 with two.

And finally, a team from RIKEN (Japan) achieved 99.84 percent fidelity in a one-qubit system and 99.51 percent with two qubits.

“When errors are so rare, it is possible to detect and correct them when they occur“, says Professor Andrea Morello, lead author of the UNSW study, and concludes that “andhis research is an important milestone on the path to quantum supremacy“.

The UNSW system encodes information in the nuclear spins of phosphorus atoms, implanted on a silicon chip. The nuclei of these atoms are the core of the processor, which performs quantum operations, and they are connected to each other by means of an electron.

“If you have two nuclei connected to the same electron, you can make them perform a quantum operation. As long as you don’t operate the electron, those nuclei safely store their quantum information. But now you have the option to make them talk to each other through the electron,” resume el Dr. Mateusz Mądzik.

The Delft and RIKEN experiments were carried out using the spins of two electrons as qubits, each confined to a quantum dot made of silicon and an alloy of silicon and germanium.

All three teams exceeded 99 percent accuracy, so the researchers say the next steps are to design practical silicon quantum processors that can be scaled up to commercial quantum computers, which is the next big thing.