Atomic coherence - Citizendia

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. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. In Physics, coherence is a property of waves that enables stationary (i History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny The electromagnetic field is a physical field produced by electrically charged objects.

If a coherent, narrow bandwidth laser is applied to a two-level system, the wave function will undergo Rabi flopping (Rabi oscillation) between the ground and excited states. In Physics, the Rabi cycle is the cyclic behaviour of a Two-state quantum system in the presence of an oscillatory driving field At some point in time the system will undergo spontaneous decay and its wave function will collapse to the ground-state wave function. Spontaneous emission is the process by which a light source such as an Atom, Molecule, Nanocrystal or nucleus in an Excited state From there on, a new Rabi oscillation will start until the next spontaneous decay. In Physics, the Rabi cycle is the cyclic behaviour of a Two-state quantum system in the presence of an oscillatory driving field Each spontaneous decay essentially 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 begin 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. In Physics, the Rabi cycle is the cyclic behaviour of a Two-state quantum system in the presence of an oscillatory driving field For this reason fewer and fewer atoms will be in-phase as time passes by. This is called decoherence (meaning individual systems, e. In Quantum mechanics, quantum decoherence is the mechanism by which quantum systems interact with their environments to exhibit probabilistically additive behavior g. atoms, are no longer coherent with each other).

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. Electromagnetically induced transparency (EIT is a coherent optical nonlinearity which renders a medium transparent over a narrow spectral range