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A lab-based test of the gravitational redshift with a miniature clock network
Xin Zheng1, Jonathan Dolde1, Matthew C Cambria1
1Department of Physics, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Nature Communications
|August 12, 2023
Summary
Scientists tested Einstein's theory of general relativity by comparing atomic clocks at different heights. The experiment confirmed the predicted gravitational redshift, showing clocks tick faster in higher gravitational potential.
Area of Science:
- Physics
- General Relativity
- Quantum Mechanics
Background:
- Einstein's theory of general relativity posits that gravitational potential affects time.
- Gravitational redshift describes how gravity influences the frequency of light and timekeeping.
Purpose of the Study:
- To conduct a laboratory-based, blinded test of the gravitational redshift.
- To measure the frequency gradient due to gravitational potential differences with high precision.
Main Methods:
- Utilized differential clock comparisons between 5 atomic ensembles.
- Spanned a height difference of 1 cm to measure frequency gradients.
- Employed a blinded experimental setup for objectivity.
Main Results:
- Measured a fractional frequency gradient of -12.4 ± 0.7 (stat) ± 2.5 (sys) × 10^-19/cm.
- Results align with the predicted redshift gradient of -10.9 × 10^-19/cm from general relativity.
- Demonstrated sensitivity to millimeter-scale height changes, enabling relativistic gravitational potential measurements.
Conclusions:
- The experiment provides strong laboratory evidence for gravitational redshift.
- Highlights the potential of differential clock comparisons for geodesy and fundamental physics.
- Suggests applications in searches for new physics, gravitational wave detection, and quantum gravity research.
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