Quantum Mechanics
In non-relativistic quantum mechanics, the transmission coefficient and related reflection coefficient are used to describe the behavior of waves incident on a barrier. The transmission coefficient represents the probability flux of the transmitted wave relative to that of the incident wave. It is often used to describe the probability of a particle tunneling through a barrier.
The transmission coefficient is defined in terms of the incident and transmitted probability current density j according to:
where Jinc is the probability current in the wave incident upon the barrier with normal unit vector and Jtrans is the probability current in the wave moving away from the barrier on the other side.
The reflection coefficient R is defined analogously, as R=|jreflected|/|jincident|. Conservation of probability implies that T+R=1, which in one dimension reduces to the fact that the sum of the transmitted and reflected currents is equal in magnitude to the incident current.
For sample calculations, see rectangular potential barrier.
Read more about this topic: Transmission Coefficient
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