For years, physicists have worked to design clocks capable of measuring incredibly small durations of time with extreme precision. Quantum clocks, in particular, have advanced this goal by using the strange and powerful principles of quantum mechanics to reach astonishing levels of accuracy.
Yet, there has always been a trade-off. As these clocks become more precise, they consume more energy and generate more entropy—essentially, disorder and wasted heat. This link between precision and thermodynamic cost has long been considered unavoidable.
Now, an international team of researchers has proposed a bold alternative. They have developed a new framework for building quantum clocks that can operate with remarkable precision while consuming far less energy. This advancement could reshape the way we build timekeeping devices and open the door to more efficient quantum technologies, including quantum computers.
An Almost Dissipation-Free Quantum Clock
The inspiration for this new type of clock emerged at the 2023 Quantum Thermodynamics Conference in Vienna. Researchers sought to challenge the foundational assumptions of timekeeping at the quantum level.
Conventional clocks—including quantum ones—work by counting a series of repeated, irreversible events, such as a pendulum swinging or an atom jumping between energy levels. Each tick of the clock produces a small amount of heat, increasing entropy. In existing designs, increasing precision has always meant increasing entropy proportionally.
The new approach breaks this long-standing link. Rather than treating each tick as an individual event to be observed and recorded—actions that consume energy—the researchers studied what would happen if quantum events could evolve smoothly and coherently, like a wave, without interruption. This method, known as coherent quantum transport, allows the system to track the overall flow of time without disturbing it.
Instead of registering every tick, the clock measures accumulated quantum excitations—tiny packets of energy—as they pass through the system. It’s similar to using an hourglass, where rather than counting each grain of sand, time is measured by waiting until a noticeable quantity has passed through. This allows for high precision, but with fewer interruptions and less energy loss.
By avoiding intermediate measurements and allowing quantum processes to unfold naturally, the system minimizes entropy production. As a result, the relationship between precision and entropy is no longer linear. Improving precision no longer requires doubling the energy cost—entropy increases only gradually as precision improves, marking a significant gain in efficiency.
A Major Leap for Quantum Timekeeping
The proposed design is based on quantum many-body systems, where particles act in a coordinated, wave-like fashion. This kind of collective behavior enables precise control without the usual thermodynamic penalties.
Theoretical models support the concept, and practical development is already underway. At Chalmers University of Technology in Sweden, researchers are working on a prototype using superconducting circuits.
While energy dissipation isn’t yet a critical issue for the most advanced atomic clocks, it is expected to become more significant as timekeeping technologies continue to advance. This new framework offers a glimpse into a future where we can measure time with extraordinary precision—without the high energy cost.
By Impact Lab
