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Concept
Atomic electron transition
Summary
In atomic physics and chemistry, an atomic electron transition (also called an electronic (de-)excitation, atomic transition, or quantum jump) is a change (or jump) of an electron from one energy level to another within an atom or artificial atom. It appears discontinuous as the electron "jumps" from one quantized energy level to another, typically in a few nanoseconds or less.
Electron transitions cause the emission or absorption of electromagnetic radiation in the form of quantized units called photons. Their statistics are Poissonian, and the time between jumps is exponentially distributed. The damping time constant (which ranges from nanoseconds to a few seconds) relates to the natural, pressure, and field broadening of spectral lines. The larger the energy separation of the states between which the electron jumps, the shorter the wavelength of the photon emitted. The emitted photon changes the kinetic energy of the atom, enabling the laser cooling technology to slow down the motion of atoms.
Danish physicist Niels Bohr first theorized that electrons can perform quantum jumps in 1913. Soon after, James Franck and Gustav Ludwig Hertz proved experimentally that atoms have quantized energy states.
The observability of quantum jumps was predicted by Hans Dehmelt in 1975, and they were first observed using trapped ions of barium at University of Hamburg and mercury at NIST in 1986.
In 2019, it was demonstrated in an experiment with a superconducting artificial atom consisting of two strongly-hybridized transmon qubits placed inside a readout resonator cavity at 15 mK, that the evolution of some jumps is continuous, coherent, deterministic, and reversible. On the other hand, other quantum jumps are inherently unpredictable.
Official source
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