A recently discovered compromise on how timing devices work at a fundamental level could put a hard limit on the performance of large quantum computers, according to researchers at the Vienna University of Technology.

While this problem is not entirely urgent, our ability to develop systems based on quantum operations, from behind-the-scenes prototypes to practical number-calculating giants, will depend on how reliably we can break days into smaller parts. Researchers say this feat will become increasingly difficult.

Whether you count seconds in the whisper of the Mississippi or divide them into the pendulum swing of an electron trapped in an atom, the measure of time is limited by the boundaries of physics itself. One of these limitations concerns the solution into which time can be divided. Any event measurement shorter than 5.39×10^-44 Seconds, for example, contradict theories about the fundamental functions of the universe. In other words, they don’t make any sense.

Even before we reach this hard limit in the sands of time, physicists believe there is a price to pay that could prevent us from continuing to measure smaller and smaller units. It starts sooner or later every hour. The pendulum slows, the battery dies, the atomic laser needs to be reset. This is not just an engineering task; The passage of time is a sign of the universe moving from a highly ordered state to a complex, chaotic mess called entropy.

“The measurement of time is always related to entropy,” says senior author Markus Huber, a systems engineer who leads a research group at the intersection of quantum information and quantum thermodynamics at the Vienna University of Technology.

In their newly published theorem, Huber and his team lay out the logic linking entropy to solubility as a thermodynamic phenomenon; It shows that unless you have infinite energy at your disposal, your rapidly ticking clock will eventually run into accuracy problems.

Or, as the study’s first author, theoretical physicist Florian Meyer, put it: “This means: either the clock is running fast or it is running correctly – both are impossible at the same time.” This may not be a big deal if you want to count the seconds that will remain unchanged throughout the lifetime of our universe. But for technologies like quantum computing, which rely on the variable nature of particles hovering on the edge of existence, time is of the essence.

This is not a big problem when the number of particles is low. As their numbers increase, the risk of any of them exiting the quantum critical state increases, leaving less time to perform the necessary calculations. Much research has been done to explore the potential for errors in quantum technology caused by a noisy and imperfect universe. This appears to be the first time researchers have considered the physics of timing as a potential obstacle.

“Currently, the accuracy of quantum computers is still limited by the accuracy of the components used or other factors such as electromagnetic fields,” says Huber. “But our calculations also show that today we are not far from a regime in which the fundamental limits of time measurement play a decisive role.”

Further advances in quantum computing are likely to increase stability, reduce errors and “buy time” for larger devices to perform at their best. But only time will tell whether entropy will have the final say on the power of quantum computers. Source