Overlooked atom ticks the boxes for better atomic clocks
At the heart of an atomic clock are, as the name suggests, atoms of a specific type. Different sorts of atoms have been used over the years to make sure these timepieces are as precise and stable as possible. Now, physicists at the National University of Singapore (NUS) have found that lutetium atoms could make for more stable atomic clocks.
Atomic clocks keep time to an incredibly precise degree – billionths of a second – by measuring the oscillation of light waves of the atoms when struck by a laser. Those oscillations become the "ticks" of the atomic clock.
The choice of atoms as the centerpiece can affect the precision and stability of the clock. Cesium was one of the first atoms to be used in the 1950s, running at a microwave frequency of over 9 billion ticks per second. Nowadays, atoms like strontium and ytterbium make for atomic clocks that tick some 430 trillion times a second, allowing scientists to measure events on incredibly tiny time scales.
Lutetium atoms wouldn't necessarily be any more precise than this, but they do have another benefit. To keep the clock stable, the atoms need to be perfectly isolated from the environment. That means locking them away inside a vacuum chamber, but even the tiniest temperature fluctuations can interfere with the ticking. Lutetium can ignore these distractions better than conventionally-used atoms.
"The ultimate performance of a clock comes down to the properties of the atom – how insensitive the atom is to its environment," says Murray Barrett, lead researcher on the study. "I would call lutetium top in its class."
Over six months, the researchers at NUS found that lutetium atoms were far less sensitive to temperature than anything else used in atomic clocks. The team says that lutetium-based atomic clocks would not only be more accurate, but thanks to their stability they could find wider use outside of lab settings.
The research was published in the journal Nature Communications.
Update (May 14, 2018): This article originally stated that atomic clocks contain a single atom in a vacuum chamber that is struck by a laser. This was incorrect, with a gas cloud atoms contained in a vacuum chamber. The story has now been edited and we apologize for the error. Thanks to the readers who brought this to our attention.