Resolving the gravitational redshift across a millimetre-scale atomic sample

Bothwell, T., Kennedy, C. J., Aeppli, A., Kedar, D., Robinson, J. M., Oelker, E. , Staron, A. and Ye, J. (2022) Resolving the gravitational redshift across a millimetre-scale atomic sample. Nature, 620, pp. 420-424. (doi: 10.1038/s41586-021-04349-7) (PMID:35173346)

Abstract

Einstein’s theory of general relativity states that clocks at different gravitational potentials tick at different rates relative to lab coordinates—an effect known as the gravitational redshift1. As fundamental probes of space and time, atomic clocks have long served to test this prediction at distance scales from 30 centimetres to thousands of kilometres2,3,4. Ultimately, clocks will enable the study of the union of general relativity and quantum mechanics once they become sensitive to the finite wavefunction of quantum objects oscillating in curved space-time. Towards this regime, we measure a linear frequency gradient consistent with the gravitational redshift within a single millimetre-scale sample of ultracold strontium. Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6 × 10−21. This heralds a new regime of clock operation necessitating intra-sample corrections for gravitational perturbations.

• Item Type: Articles
• Additional Information: We acknowledge funding support from the Defense Advanced Research Projects Agency, National Science Foundation QLCI OMA-2016244, the DOE Quantum System Accelerator, the National Institute of Standards and Technology, National Science Foundation Phys-1734006 and the Air Force Office for Scientific Research.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Oelker, Dr Eric
• Authors: Bothwell, T., Kennedy, C. J., Aeppli, A., Kedar, D., Robinson, J. M., Oelker, E., Staron, A., and Ye, J.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Nature
• Publisher: Nature Publishing Group
• ISSN: 0028-0836
• ISSN (Online): 1476-4687
• Published Online: 16 February 2022
• Copyright Holders: Copyright © 2022 Springer Nature
• First Published: First published in Nature 620: 420-424
• Publisher Policy: Reproduced in accordance with the publisher copyright policy