What costs more energy — running a quantum clock or observing it?
Keeping track of time seems simple. A watch ticks, a pendulum swings, and a calendar flips. But at the quantum level, marking time is far more complicated — and far more expensive than anyone expected. New research from the University of Oxford shows that reading a quantum clock uses vastly more energy than running the clock itself. The findings could reshape how future quantum technologies are built and understood. At everyday scales, clocks rely on processes that cannot be reversed, like the swing of a pendulum or the vibrations of atoms in an atomic clock. These processes naturally mark the passage of time. At the quantum scale, however, such irreversible steps are minimal or absent, making timekeeping much trickier. For technologies that depend on highly precise clocks, like quantum computers or navigation systems, understanding the energy needed to keep and read time is crucial. Until now, the thermodynamics of quantum clocks remained largely a mystery. Measuring Time Costs More Than Ticking Researchers at Oxford asked a simple but profound question: what costs more energy — …
