Quantum silicon chips exceeded 99% accuracy in three studies

Classical computers store and process information in bits, which are represented as either one or zero. Quantum computers, however, use qubits that can be one, one - zero, or both at the same time, thanks to the quantum weirdness of superposition. This should allow quantum computers to become exponentially more powerful than classical ones. However, quantum states are sensitive to external interference, which can cause errors that severely limit the practicality of these machines. But now, the three new studies have shown quantum computer systems with lower-than-error rates. one percent. Better yet, these devices were all based on silicon, which should make them easier to fabricate using existing commercial semiconductor infrastructure.

A team led by the University of New South Wales (UNSW) in Australia has achieved 99.95% fidelity in a one qubit system and 99.37% fidelity with two operating qubits. A second team, from Delft University of Technology in the Netherlands, reached 99.87% with one qubit and 99.65% with two. And finally, a team from RIKEN in Japan achieved 99.84% fidelity in a one qubit system and 99.51% with two qubits.



“When mistakes they are so rare, it becomes possible to detect and correct them when they occur, ”said Professor Andrea Morello, lead author of the UNSW study. "This shows that it is possible to build quantum computers that have enough scale and enough power to handle meaningful computations."

The UNSW system encodes information in the nuclear spins of phosphorus atoms, implanted in a silicon chip. The nuclei of these atoms are the main processor, which performs quantum operations, and are connected to each other via an electron entangled with each atom.

"If you have two nuclei connected to the same electron, you can have them do a quantum operation," explained Dr. Mateusz Mądzik, lead experimental author of the study. "While the electron isn't spinning, those nuclei securely store their quantum information. But now you have the opportunity to make them talk to each other through the electron, to carry out universal quantum operations that can be adapted to any computational problem. "

The Delft and RIKEN experiments were conducted using the spins of two electrons as qubits, each confined to a quantum dot made of silicon and a silicon-germanium alloy. With all three teams exceeding 99% accuracy, the researchers say the next steps are to design practical silicon quantum processors that can be scaled for commercial quantum computers.