This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers from Rutgers, IBM and collaborating institutions have shown that a quantum computer can check what is happening inside it and respond while it is running, repeatedly resetting parts of the system to bring chaotic behavior under control. The advance is a critical step toward building larger, more reliable quantum computers.
Today's quantum computers operate according to the unusual rules governing atoms and other extremely small particles. They could one day solve problems beyond the reach of conventional computers—designing better batteries and cleaner industrial catalysts, simulating molecules and materials too complex for today's computers, and running certain artificial intelligence programs. In a study published in Nature Physics, researchers from Rutgers, International Business Machines Corp. and collaborating institutions showed that a quantum computer can repeatedly check and reset parts of itself while running.
The experiment is among the largest demonstrations to date of real-time quantum feedback control, a capability considered essential for future quantum computers that will be fault-tolerant. Scaling quantum computers will require them to identify and correct errors while they are working, a capability known as error correction, which will allow for the construction of a fault-tolerant quantum computer. A fault-tolerant quantum computer can keep computing correctly even though its individual quantum bits are constantly making small mistakes.
No one has yet built such a device. "To build a fault-tolerant quantum computer, we have to make these checks and corrections not just once or twice, but a huge number of times during a calculation," said Jedediah Pixley, a professor in the Department of Physics and Astronomy at the Rutgers School of Arts and Sciences and the director of the Center for Materials Theory. "This experiment is a landmark on that road," said Pixley, who also is a member of the Flatiron Institute, the scientific research division of the Simons Foundation in New York, and one of the senior authors of the study.
"It says, 'OK, we've taken another important step to get there.'" The work also confirmed a prediction about quantum behavior. As researchers increased how often the computer checked and reset its fundamental information-storing units, known as qubits, the system abruptly shifted from chaos to a state they could control, showing how order can emerge from disorder. Conventional computers store information in bits, each of which is either 0 or 1.
Quantum computers use qubits, which can exist in a superposition. This means they hold multiple possibilities between 0 and 1 until they are measured, when each produces one result or the other. These properties give quantum computers their potential power but make the information they carry extremely sensitive.
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