What is Quantum Decoherence and How Does it Affect Quantum Systems?

[Katyan Anshuman]

So I whilst understanding basics of some quantum phenomena like superposition, tunnelling, fluctuations etc I happened to watch the movie "Coherence" where there's a scientifically unsatisfactory reference to quantum decoherence. What exactly is this concept?

 

[jedishrfu]

The wiki article describes it as:

In quantum mechanics, quantum decoherence is the loss of coherence or ordering of thephase angles between the components of a system in a quantum superposition. One consequence of this dephasing is classical or probabilistically additive behavior. Decoherence occurs when a system interacts with its environment in a thermodynamically irreversible way.

https://en.wikipedia.org/wiki/Quantum_decoherence