In physics, atomic coherence is the induced coherence between levels of a multi-level atomic system sometimes observed when it interacts with a coherent electromagnetic field. This is a discussion of a present category of science. ... Coherence is the property of wave-like states that enables them to exhibit interference. ... The general meaning of atomic is irreducible. That is, reduced to the smallest possible part. ... The electromagnetic field is a physical field that is produced by electrically charged objects and which affects the behaviour of charged objects in the vicinity of the field. ...
If a coherent, narrow bandwidth laser is applied to a two-level system, the wave function will start Rabi flops back and forth between ground and excited states. At some point in time the system will undergo spontaneous decay and its wave function will collapse to the ground-state wave function. From there on, a new Rabi oscillation will start until the next spontaneous decay. Each spontaneous decay basically changes the phase of the Rabi oscillation. If instead of single two-level system there is a large collection of identical two-level systems (like a lot of the same species atoms), then all of them will start Rabi oscillation at the same time, and therefore all of them will be in phase with each other. But due to the spontaneous decay different atoms will collapse to their ground-state at different (and random) times and start a new Rabi oscillation. For this reason fewer and fewer atoms will be in-phase as time passes by. This is called "loss of coherence" or "De-Coherence" (meaning individual systems (e.g. atoms) are not coherent with each other any more). The Rabi cycle is a term from the field of quantum optics. ... The Rabi cycle is a term from the field of quantum optics. ... The Rabi cycle is a term from the field of quantum optics. ... The Rabi cycle is a term from the field of quantum optics. ...
Atomic coherence can involve more than two levels and its preparation more than a single laser.
An atomic coherence is essential in research on several effects, such as electromagnetically induced transparency (EIT), lasing without inversion (LWI), enhanced dispersion without absorption, Stimulated Raman Adiabatic Passage (STIRAP) and nonlinear optical interaction with enhanced efficiency. The effect of EIT on a typical absorption line. ...
Atomic physicists are hoping that the invention of the "atom laser" will spark a similar revolution in the field of atom optics, or matter-wave optics as it is also known.
Because the output-coupling methods are coherent, it is likely that the coherence length of the lasers in figure 3 is in fact much larger than the size of the condensate.
Although this increases the spatial coherence of the matter waves, it is at the expense of the flux or number of atoms available for the duration of the experiment (which is often determined by the overstretched patience of the graduate student).
This induced atomiccoherence is essential in creating novel effects, such as electromagnetically induced transparency (EIT), enhanced dispersion without absorption, slowing down the speed of a light beam, and enhanced nonlinear optical processes.
This atomiccoherence is essential in creating novel effects, such as electromagnetically induced transparency (EIT) and lasing without inversion (LWI), enhanced dispersion without absorption, and enhanced nonlinear optical efficiencies.
We believe that these coherence and quantum interference effects in multi-level systems will have practical applications in photonic devices in solid materials (such as semiconductor quantum well structures and optical crystals) by modifying the absorption and dispersion properties of the media.
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