Atomic electron transition

In atomic physics and chemistry, an atomic electron transition is when an electron moves from one energy level to another inside an atom or an artificial atom.

Electrons can lose energy by releasing electromagnetic radiation in the form of a photon, moving to a lower energy level. They can also gain energy by absorbing photons, which lifts them to a higher energy level. The bigger the gap between the energy levels, the shorter the wavelength of the photons involved. This process helps scientists understand atoms.

History

In 1913, a scientist named Niels Bohr said that electrons can move between different energy levels in an atom. Later, James Franck and Gustav Ludwig Hertz proved through experiments that atoms have these special energy levels.

In 1975, another scientist named Hans Dehmelt thought we might one day see these moves. In 1986, scientists saw these moves for the first time using trapped atoms of barium and mercury.

Theory

An atom can interact with a moving electric field. This happens when the atom is exposed to light or other radiation. Because of this, the atom’s tiny parts can move from one energy level to another.

Special math rules describe how this works. One important rule is called Fermi’s golden rule. It helps us understand how often these moves between energy levels happen. The rule shows that the chance of a move depends on things like the strength of the electric field and the atom’s selection rules. These rules decide which moves are allowed.

E ( t ) = | E 0 | R e ( e − i ω t e ^ r a d ) {\displaystyle E(t)=|{\textbf {E}}_{0}|Re(e^{-i{\omega }t}{\hat {\textbf {e}}}_{\mathrm {rad} })}

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Electromagnetic radiation interactions

To move an electron to a higher energy level in an atom, a piece of light called a photon must give the electron the right amount of energy. This energy is like the strength of ultraviolet (UV) and X-ray light. Special tools like UV and X-ray lasers can help us study how electrons move.

When an electron moves back down to a lower energy level, it can give off this energy as light. We can use different ways to see this light and learn about the atoms in a sample. For example, shining UV or visible light on a sample can show us how much light passes through or is blocked, helping us know what the sample is made of.

Recent discoveries

In 2019, scientists did an experiment with a special kind of artificial atom made from two transmon qubits. They put these qubits in very cold temperatures of 15 mK. They found that some changes in energy happen in a smooth way and can even be reversed. But other changes are hard to predict.