Quantum Leap Double the Time, Double the Accuracy!

Article Heading: Two Different Time Scales Could Increase Quantum Clock Accuracy Exponentially

The quest for ever-more-accurate measurements is a driving force in science, pushing the boundaries of what's possible. In the realm of quantum metrology, researchers are exploring how the bizarre properties of quantum particles can be harnessed to create incredibly precise instruments. One prime example is the atomic clock, which leverages quantum mechanics to measure time far more accurately than conventional clocks.

However, quantum physics inherently involves a degree of uncertainty, a statistical noise that imposes fundamental limits on achievable accuracy. For a long time, it seemed an unbreakable rule that doubling the accuracy of a clock would require at least twice as much energy. But now, a groundbreaking study reveals that this limitation can be overcome with clever quantum tricks.

A team of researchers from TU Wien, Chalmers University of Technology (Sweden), and the University of Malta has demonstrated that accuracy can be increased exponentially by using two distinct time scales – much like the second and minute hands on a traditional clock. The findings, published in Nature Physics, could revolutionize quantum measurement.

What Makes a Clock Tick?

"We have analyzed in principle which clocks could be theoretically possible," explains Prof. Marcus Huber from the Atomic Institute at TU Wien. "Every clock needs two components: first, a time base generator, such as a pendulum in a pendulum clock, or even a quantum oscillation. And second, a counter—any element that counts how many time units defined by the time base generator have already passed."

The time base generator must be able to return to its initial state after each cycle, while the counter needs to change to mark the passage of time. This process, according to Florian Meier from TU Wien, is inherently linked to entropy. "This means that every clock must be connected to an irreversible process," says Meier. "In the language of thermodynamics, this means that every clock increases the entropy in the universe; otherwise, it is not a clock."

Previously, it was believed that the precision of a clock was linearly related to the amount of entropy it generated. "Until now, there seemed to be a linear relationship: if you want a thousand times the precision, you have to generate at least a thousand times as much entropy and expend a thousand times as much energy," says Prof. Huber.

Quantum Time vs. Classical Time: Breaking the Linearity

The new research demonstrates that this linear relationship can be bypassed. The key is to utilize two different time scales, exploiting the unique properties of quantum mechanics.

"For example, you can use particles that move from one area to another to measure time, similar to how grains of sand indicate the time by falling from the top of the glass to the bottom," says Meier. Connecting these devices in series and counting their cycles allows for increased accuracy, but traditionally requires more energy and generates more entropy.

However, quantum physics introduces a new possibility: particles can travel through the entire system without being measured at intermediate points. In essence, the particle exists in multiple locations simultaneously until it reaches its final destination and is measured. This final measurement is the only irreversible, entropy-generating step.

The Quantum Advantage: Two Hands on the Quantum Clock

"So we have a fast process that does not cause entropy—quantum transport—and a slow one, namely the arrival of the particle at the very end," explains Yuri Minoguchi of TU Wien. "The crucial thing about our method is that one hand behaves purely in terms of quantum physics, and only the other, slower hand actually has an entropy-generating effect."

This innovative approach allows for an exponential increase in accuracy per unit of entropy generated. The implications are significant:

• Higher Precision: Achieve significantly higher precision than previously thought possible.
• Energy Efficiency: Improve energy efficiency in quantum clocks and other quantum measurement devices.
• Fundamental Understanding: Deepen our understanding of the relationship between quantum physics and thermodynamics.

Furthermore, the team believes that the theory can be tested using superconducting circuits, a leading technology in the development of quantum computers.

Looking Ahead: Quantum Clocks and the Future of Measurement

"This is an important result for research into high-precision quantum measurements and the suppression of unwanted fluctuations," says Prof. Huber, "and at the same time it helps us to better understand one of the great unsolved mysteries of physics: the connection between quantum physics and thermodynamics."

This breakthrough offers a tantalizing glimpse into the future of quantum metrology, where harnessing the unique properties of quantum mechanics could lead to unprecedented levels of precision and a deeper understanding of the fundamental laws governing our universe. The development of more accurate quantum clocks has implications for many areas of science, from fundamental physics research to navigation and communication technologies. The future is ticking, and it's doing so with quantum precision.

More information: Florian Meier et al, Precision is not limited by the second law of thermodynamics, Nature Physics (2025). DOI: 10.1038/s41567-025-02929-2

Journal information: Nature Physics

Tags: Quantum clock, Quantum metrology, Atomic clock, Quantum physics, Accuracy limits, Energy efficiency, Time measurement, TU Wien, Quantum particles, Statistical noise

Source: https://phys.org/news/2025-06-scales-quantum-clock-accuracy-exponentially.html