Quantum Breakthrough Could Sharpen Atomic Clocks — A Step Toward Interstellar Navigation

Researchers use quantum tricks to push atomic-clock precision beyond current limits

Atomic clocks already lose only about one second over roughly 10 million years and power everything from car GPS to precision science. Now two independent teams report quantum-based techniques that could make these clocks markedly more stable and accurate — advances that might one day enable more precise deep-space navigation and boost sensors used to study earthquakes or dark matter.

How atomic clocks keep time

Many satellite navigation systems depend on signals exchanged with satellites more than 12,000 miles above Earth. Inside those satellites are atomic clocks — devices that measure time by tracking electrons jumping between energy levels in atoms such as rubidium, strontium, or ytterbium. Because they measure the frequency of electromagnetic radiation that drives those jumps, atomic clocks suffer far less drift than mechanical timekeepers and are central to modern navigation and scientific measurement.

Two quantum strategies to beat the quantum limit

Scientists are now pushing atomic clocks further: not only to increase accuracy but to make them more compact and field-ready. Two recent papers — one led by Vladan Vuletić and colleagues in Nature, and another from a team at the University of Sydney in Science Advances — explore different quantum approaches to overcome the conventional limits on measurement precision in ultra-accurate optical atomic clocks.

MIT-led approach (entanglement): Optical clocks that use ytterbium atoms operate at very high oscillation frequencies, enabling them to resolve extremely short intervals of time. That sensitivity makes them vulnerable to quantum noise — fundamental fluctuations related to Heisenberg’s Uncertainty Principle that limit how precisely the atoms’ oscillations can be measured. Vuletić and colleagues showed that by entangling many ytterbium atoms with strong, high-frequency laser light, they could reduce that quantum noise and roughly double the clock’s precision for a given number of atoms. Entanglement — often described as quantum correlation — lets a clock perform better without simply adding more particles.

University of Sydney approach (targeted measurement): A separate team developed a protocol that focuses on detecting only very small changes in a quantum system while deliberately discarding broader, global information. The strategy is analogous to reading an analog clock that has only a minute hand: you can resolve the minutes very precisely but lose information about the hour. By "throwing away" large-scale information and concentrating sensitivity on tiny displacements, the researchers define a new uncertainty bound that permits simultaneous, high-precision readings of complementary properties without violating Heisenberg’s principle. This approach could be especially useful for highly charged-ion clocks, which are promising for extreme accuracy but difficult to probe directly using existing methods like quantum logic spectroscopy.

Why this matters

Although an interstellar GPS is still science fiction for now, next-generation atomic clocks could play a crucial role in deep-space navigation: by forming a network of clocks in space or by carrying ultra-stable clocks aboard long-range probes. Extremely precise and stable timekeeping helps determine a spacecraft’s position to fine margins and could enable autonomous navigation across vast distances.

Beyond navigation, the improved clocks and sensing techniques may have other scientific uses: detecting subtle signatures of dark matter, forecasting seismic events with greater lead time, and refining fundamental tests of physics. For researchers, the present moment is fertile: new quantum methods are opening practical pathways to make the most precise clocks yet.

“All these clocks are intrinsically quantum,” said Vladan Vuletić, reflecting that their operation depends on detecting atomic and subatomic motion. “With quantum entanglement... you can make future clocks that operate better for that given number of particles.”

Sources: recent papers in Nature and Science Advances; statements from authors.