JILA Atomic Clock measures Einstein’s general theory of relativity on a millimeter scale

In this small cloud of strontium atoms, JILA researchers have measured how the time dilation, the ticking velocity of an atomic clock, changes with altitude. Credit: Jacobson / NIST

JILA physicists have measured Albert Einstein’s general theory of relativity, more specifically, an effect called time dilation, on the smallest scale ever. This is a different rate for two small atomic clocks separated by a width of only 1 mm or the tip of a sharp pencil.

Experiments described in the February 17th issue of Nature, It proposes a way to make atomic clocks 50 times more accurate than today’s best designs, and provides a route to clarify how the theory of relativity and gravity interact. Quantum mechanicsA major challenge in physics.

JILA is jointly run by the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

“The most important and exciting result is that we can potentially connect. Quantum physics Jun Ye, a NIST / JILA Fellow, uses gravity to explore complex physics, for example, when particles are distributed in different parts of a curved space-time. More accurate than today. This is great news. “

Einstein’s 1915 Theory of general relativity There are important practical applications such as modifying GPS satellite measurements, explaining large-scale effects such as gravity effects on time. The theory is more than a century old, but physicists are still fascinated by it. NIST scientists used the atomic clock as a sensor to measure relativity more accurately. This may help to finally explain how the effect interacts with quantum mechanics, the rulebook of the subatomic world.

According to the general theory of relativity, atomic clocks at different altitudes in the gravitational field tick at different velocities. When observed with stronger gravity, closer to Earth, the frequency of atomic radiation decreases and shifts towards the red edge of the electromagnetic spectrum. In other words, the lower the altitude, the slower the clock ticks. This effect has been repeatedly demonstrated. for example, NIST physicists measured it in 2010 By comparing two independent atomic clocks, one is placed 33 centimeters (about 1 foot) above the other.

JILA researchers have measured the frequency shift between the top and bottom of a single sample of about 100,000 cryogenic strontium atoms loaded into the optical lattice. Old atomic clock.. In this new case, the grid, which can be visualized as a stack of pancakes created by a laser beam, has an unusually large, flat, thin cake and is formed with weaker light than normally used. This design reduces lattice distortion, which is typically caused by light and atomic scattering, homogenizes the sample, and extends the atomic wave. Its shape indicates the probability of finding an atom at a particular location. The energy state of the atom is so well controlled that it checks exactly for 37 seconds between the two energy levels. This is a record of so-called quantum coherence.

Important for new results is your group Imaging innovationWe provided a microscopic map of the frequency distribution across the sample and a way to compare two regions of the atomic cloud rather than the traditional approach of using two separate clocks.

The redshift measured across the atomic cloud was small in the region 0.0000000000000000001 and was in line with the prediction. (It’s too small for humans to perceive directly, but the difference has a huge impact not only on technologies such as GPS, but also on space.) The research team found about 30 minutes of average data in this type of experiment. Resolved this difference quickly. .. After 90 hours of data, their measurement accuracy was 50 times better than any previous watch comparison.

“This is a completely new ball game, a new system that allows us to explore the quantum mechanics of curved space-time,” Ye said. “If we can measure the redshift 10 times more than this, we can see the de Broglie wave of the atom that crosses the curvature of space-time. If we can measure the time difference on such a fine scale, we can do the following: For example, discover that gravity destroys quantum coherence. This may be the basis of why our macroscale world is classic. “

Better watches have many uses beyond timekeeping and navigation.You suggest Atomic clock It can function as both a microscope for observing the subtle connections between quantum mechanics and gravity, and a telescope for observing the deepest corners of the universe.He uses his watch to look for strange things Dark matter, Is believed to make up most of the matter in the universe.Atomic clocks are also ready to improve their understanding of models and the shape of the Earth through the application of measurement science called. Relativistic geodesy..

Ultra-precision atomic clock for the discovery of new physics

For more information:
Tobias Bothwell, Solving Gravitational Redshift in Millimeter-Scale Atomic Samples, Nature (2022). DOI: 10.1038 / s41586-021-04349-7..

Related: Shimon Kolkowitz, Comparison of Differential Clocks with Multiplexed Optical Lattice Clocks, Nature (2022). DOI: 10.1038 / s41586-021-04344-y..

Quote: JILA Atomic Clock is a millimeter of Einstein’s general theory of relativity obtained from https: // on February 16, 2022. Measured on a scale (February 16, 2022)

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JILA Atomic Clock measures Einstein’s general theory of relativity on a millimeter scale

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