Atomic clocks may finally detect dark matter, study suggests: ScienceAlert

Atomic clocks are the most accurate time-measuring tools we have. A new study proposes a way to use the incredible level of resolution of instruments to detect the smallest energy fluctuations, which could give scientists a way to observe some types of dark matter.

Dark matter remains elusive: although we have not observed it directly, we can see its effects on the universe. Frustratingly, there is nothing in our current physical models to explain what we see.

Here, researchers from the University of Sussex and the UK’s National Physical Laboratory have proposed using atomic clocks to detect some of the low-mass particles thought to make up this mysterious substance.

The idea is that these particles interact with ordinary matter particles, but very weakly. Atomic clocks rely on almost imperceptible oscillations of atoms as they move between energy states to tell time, so even the slightest hit of these oscillations — from ultralight dark matter particles, for example — can be detected.

First, the researchers proposed some theoretical models for how to measure changes in atomic clock time. Next, they took readings from existing atomic clocks to help prove the feasibility of this approach.

The next step will be to conduct an experiment where two atomic clocks can be compared: one that is more susceptible to changes in what are known as fundamental constants, or fixed values ​​on which the laws of the universe are based.

In this particular study, two fundamental constants were considered: the fine structure constant, which describes how strongly the electrons are attracted to the protons in the atom, and the electron-to-proton mass ratio, which indicates the “heaviness” of the atoms.

Both constants can be disrupted by interactions with some light particles that are seen to be responsible for dark matter effects, such as the virtual axis. This study places limits on the magnitude of differences that might indicate the presence of particles.

There’s obviously a lot of theory here, and we’re dealing with a lot of assumptions and predictions – although they’re very clever. Ultimately, however, minute changes in the ticking of the atomic clock can have profound effects on physics.

Atomic clocks are extremely useful to scientists, as they can calculate time with unparalleled accuracy over billions of years. They have been used to measure gravitational redshift for example, the way gravity can interfere with time.

They are also important in quantum physics as well, and have opened up areas of research into ways in which quantum information can be transmitted or stored. It now appears that they could be dark matter detectors as well.

The researchers say that these results do not depend on any pre-existing theories, and the models produced are very flexible, perhaps sufficient to apply them beyond dark matter and to other unexplained phenomena.

The research was published in New Journal of Physics.