A potential well
is the region surrounding a local minimum
of potential energy
. Energy captured in a potential well is unable to convert to another type of energy (kinetic energy
in the case of a gravitational
potential well) because it is captured in the local minimum of a potential well. Therefore, a body may not proceed to the global minimum of potential energy, as it would naturally tend to due to entropy
Energy may be released from a potential well if sufficient energy is added to the system such that the local minimum is surmounted. In quantum physics
, potential energy may escape a potential well without added energy due to the probabilistic
characteristics of quantum particles
; in these cases a particle may be imagined to tunnel through
the walls of a potential well.
The graph of a 2D potential energy function is a potential energy surface that can be imagined as the Earth's surface in a landscape of hills and valleys. Then a potential well would be a valley surrounded on all sides with higher terrain, which thus could be filled with water (i.e., be a lake) without any water flowing away toward another, lower minimum (i.e. sea level).
In the case of gravity, the region around a mass is a gravitational potential well, unless the density of the mass is so low that tidal forces from other masses are greater than the gravity of the body itself.
A potential hill is the opposite of a potential well, and is the region surrounding a local maximum.
Quantum confinement describes the increase in energy which occurs when the motion of a particle is restricted in one or more dimensions by a potential well. When the confining dimension is large compared to the wavelength of the particle, the particle behaves as if it were free. As the confining dimension decreases, the particle's energy increases. A quantum dot
is a well that confines in all three dimensions such as a small sphere, a quantum wire
confines in two dimensions, and a quantum well
confines in one dimension.
- Buhro WE, Colvin VL (2003). "Semiconductor nanocrystals: Shape matters". Nat Mater 2 (3): 138–9.