Sunday , September 20 2020

Simple new gravimetric method – Sciencetimes



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The University of California at Berkeley has discovered a new way to measure gravity with the shades of two atoms in super-suspended laser-assisted air. The team explained that the new gravimetric method is much more useful than traditional gravimetric methods.

Traditionally, scientists measure the impact of gravity on atoms by observing how fast atoms fall from high places. Such experiments can help test Einstein's theory of gravity and accurately measure the basic gravitational gravitas. However, a few meters of pipe devices used in falling-down experiments may have difficulty preventing interference, such as magnetic fields.

To overcome this challenge, scientists have developed a breakthrough technique to measure Earth's gravity using a new mass-built device. They devised a new way to measure and float atoms in the air a few millimeters high with laser light.

Conceptual diagram of superposition cesium atoms ⓒ Sarah Davis

Conceptual diagram of superposition cesium atoms ⓒ Sarah Davis

According to a paper published in the journal Science Friday, a newly designed device can better test the gravitational force acting on small matter.

This technique can also be used to measure the smallest changes in gravity that occur in many parts of the world. This can help map the ocean floor or find underground oil or minerals.

Laser cesium atoms floating in the air

Victoria Xu, a physicist at the University of California, Berkeley and colleagues launched a cesium atom cloud into the air, then separated each of the cesium atoms into light-overlapping states.

When protons reach this strange state of uncertainty, each atom appears to be in two "simultaneous" positions at the same time. One atom has a few micrometers higher than the other. The team captures these separated cesium atoms in the air with laser light.

To measure gravity using atoms held in place without pulling out of the gravitational field, the duality of atoms must be used. Duality refers to the fact that the atom has both particle and wave properties.

This quantum effect means that atoms, like particles, act like waves, just as light that moves like waves acts like particles called photons. Each cesium atom in this overlap is slightly different in its position in the Earth's gravitational field.

The wave of the atom at the higher position is slightly faster than the cesium atom at the bottom. By observing these differences between these two atoms, physicists can calculate Earth's gravitational force at that moment.

MIT physicist Alan Jamieson explained in an interview with Science News: "The biggest advantage of this new technology is that it enables controlled measurements."

"It's pretty hard to make this drop on a 10-meter tower," he said. Magnetic fields are difficult to defend, especially since magnetic fields are created everywhere in all electrical systems in buildings. Gravity can be avoided with the new method of measurement.

It can be used as a portable device for measuring gravity

This new method can be measured over a long period of time because the atoms are not moving. In addition, since the measuring equipment is very small, a portable measuring device can be made to measure gravity at different positions.

New desktop gravity measuring equipment. The purple laser puts the cesium atoms in a closed chamber. Ⓒ Victoria Xu

New desktop gravity measuring equipment. The purple laser puts the cesium atoms in a closed chamber. Ⓒ Victoria Xu

Co-researcher Holger Miller said that if you can measure with such a simple device, you can measure shorter gravity effects.

For example, instead of measuring the weight of the earth, you can measure the weight of small things like marble. It can help identify mineral deposits and help draw topography to the seabed.

In addition, the new gravimetric method can be useful for scientists who want to understand the nature of dark matter and to test other ideas in physics, such as the principle of equivalence.

Kai Bongs, a physicist at the University of Birmingham, UK, said he could envisage using a new kind of atomic gravimeter to investigate the nature of dark matter or to test the basic features of the "equivalent principle" of Einstein's theory of gravity. .

The unification theory that physicists dream about is a balance between quantum mechanics and Einstein's theory of gravity, but it has not been successful. Because the two are in agreement, they violate the principle of equivalence.

Kai Bong said finding the difference gives rise to high expectations that it could lead to unification theory.

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