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Line 1: − + − Quantum wells are used in many modern devices, including lasers, light detectors, transistors (the computer you are using right now contains around a billion!). Some of the newest LCD computer monitors use quantum wells to give ultra-fast switching in their backlighting.+ + + + + + + + + + +
rewritten to make things clearer
A '''quantum well''' is a narrow dip in [[potential energy]], which can be used to store [[electron]]s or other charged particles. A quantum well could be created by sandwiching two materials together, such as a thin sheet of metal between two blocks of rubber. An infinitely deep quantum well would have a voltage of 0V in the middle, and infinity in the barriers.
A '''quantum well''' is a device for storing [[electron]]s or other charged particles. They are used in many different types of modern technology, including computers, lasers and solar panels.
== How it works ==
Imagine a ball rolling into the [[Grand Canyon]], it will fall to the bottom and cannot get back out unless a lot of energy is used (for example, someone at the bottom of the well could fire it out of a cannon!).
A quantum well works in a very similar way. Electrical forces keep charged particles (such as [[electron]]s) inside the well, just like [[gravity]] keeps a ball inside the Grand Canyon.
A second important difference is that quantum wells are very small (about 1000th of the width of a human hair). At these scales, [[quantum mechanics|quantum effects]] come into play. This means that the electron may only have certain, fixed energy levels. Think of this as being like standing on a ladder - you can only stand on the rungs, not the gaps in-between.
== Why this is useful ==
[[Einstein]] won a [[Nobel prize]] by showing that the energy in a beam of light is actually contained in lots of small packets called [[photon]]s, rather than being spread out evenly in the beam. The energy stored in each photon depends on the colour of the light.
The electron may only take certain, fixed energies inside the quantum well. This means that the electron can only absorb or release fixed amounts of energy (or certain colours of light). This makes quantum wells extremely useful in devices which convert a particular colour of light to electricity (or vice versa), such as lasers, [[LED]]s and solar panels.