Atomic clocks used at the National Physics Laboratory

Scientists at Sussex and the National Physical Laboratory (NPL) have teamed up to search for experimental evidence of a breakdown in the laws of physics.

The project, led by Sussex Professor Xavier Calmet and Dr Rachel Godun from NPL, was based on examining the rate at which atomic clocks ‘tick’.

According to the currently established laws of physics, clocks should tick at a constant rate. However, many theories that predict modifications beyond the standard model would cause tiny changes in atomic energy levels, which would affect the rate at which clocks tick. Thus a vast variety of different physics models can be probed with high-precision atomic clocks. 
 
The teams at Sussex and NPL developed a new theoretical framework to probe generic new physics with clocks and were able to derive the first model independent limits on physics beyond the standard model.

They also placed competitive constraints on possible couplings between ultralight scalar dark matter and ordinary matter, as well as showing that data from atomic clocks could be used in future to study axion-like couplings with greater sensitivity than neutron electric dipole moment experiments.

Prof Calmet said: "Leading this interdisciplinary project was an amazing experience. We are creating a new field at the interface of Atomic, Molecular and Optical (AMO) physics and traditional particle physics. The future of particle physics is not with big colliders, but rather with tabletop experiments which could discover exciting new phenomena such as dark matter."

"We are literally doing cosmology and astrophysics in the lab."

The results are due to be published in New Journal of Physics with first authors Nathaniel Sherrill, a postdoctoral scholar at Sussex and Adam Parsons, a Higher Scientist at NPL.

This work will help achieve a better understanding of the nature of matter in our universe, which could lead to answering some of the big questions in modern physics, such as reconciling differences in the theories of gravitation and quantum physics.

Nathaniel said: "Working closely with experimentalists at NPL was especially insightful and rewarding. Together we were able to better demonstrate the breadth of new physics that can be studied with quantum sensors."
 
The research was supported by a UKRI grant which finances QSNET, a collaboration between the University of Birmingham, Imperial College, NPL and Sussex.

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