Probing Foundations of Spacetime with Atom Interferometers

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• Jeremiah Mitchell (Cavendish Laboratory and Queen's College, Cambridge)
• Monday 12 May 2025, 14:30-15:30
• MR9, Centre for Mathematical Sciences, Wilberforce Road, Cambridge.

If you have a question about this talk, please contact Adrian Kent.

Quantum sensors such as atom interferometers have been rapidly evolving into extremely precise platforms for simultaneously testing foundations of quantum mechanics and gravity. Their first generations were precise tabletop inertial sensors measuring accelerations and rotations of the ultracold atom ensembles sourced by their environment. These branched off into mobile and long-baseline instruments capable of acting as precise gravimeters and platforms for testing the Einstein Equivalence Principle. Future detectors coming online in the next few years will extend the scale of the instruments from 10s of meters to 100s and 1000s of meters opening the door for further investigations of the macroscopic validity of quantum mechanics and tests of relativistic gravity. In this talk I will introduce some examples of these long-baseline atom interferometers, discuss the foundations of quantum mechanics and general relativity that may be probed, and finally present the current state of these experiments and technical/environmental limitations that exist. AION and MAGIS -100 are terrestrial long-baseline detectors being developed to search for ultralight dark matter and gravitational waves, but fundamentally their operation relies on macroscopic manipulation of quantum systems in free-fall. In this context, I will present some models of decoherence, via gravitational collapse and time-dilation, and tests of the nonlinearity of gravity that have been proposed and the limits of these quantum sensors for experimental tests and the plethora of noise sources competing with these signals. Finally, some open questions and routes of inquiry will be addressed.

This talk is part of the Foundations of Physics seminar series.

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