Quantum computers are not yet fully reliable – they are far too unstable. However, all around the world, people are trying to improve them – some of whom are based in Norway.
“In quantum computers, information is transmitted and stored using so-called qubits (quantum bits). But quantum information can quickly be lost,” said Jeroen Danon, a professor at the Norwegian University of Science and Technology (NTNU) Department of Physics.
One of the main problems is that it is difficult to determine how quickly the information is lost.
No accurate measurement method
“In the widely used superconducting qubits, the time it takes for information to disappear is, on average, reasonable. But it seems to vary randomly over time,” explained Danon.
So, it is really unfortunate that we don't even have any fast but reliable measurement methods to determine how long it takes before information in qubits is lost, he said. It is, of course, absolutely necessary to resolve this problem to be able to get quantum computers to operate more stably than they currently do.
Now Danon and his colleagues have come up with a solution:
“In collaboration with an international team led by the Niels Bohr Institute in Copenhagen, we have developed a new measurement method. It enables us to measure the time it takes to lose information with unparalleled speed and accuracy,” said Danon.
100 times faster
Previously, it took around 1 second to measure how long it takes before the information is gone. In this context, that is a veeeeeery long time.
“We managed to do it in approximately 10 milliseconds, i.e. more than 100 times faster. And more or less in real time,” Danon said.
As a result, they can monitor the loss of information much more accurately as it takes place. In addition, they are able to observe small and rapid changes that were previously invisible.
“This will in turn make it easier to identify the underlying causes that make the information disappear,” he said.
The research findings change how we should calibrate and test quantum processors, enabling us to learn more about the microscopic processes that limit the performance of today’s quantum computers. And that is good news.