When reading in the web about decoherence especially in popular articles I find very often explanations that point out the fact that the enviroment has a large number of degrees of freedom. It is unclear to me in which extent and in which aspects this is relevant for decoherence.(adsbygoogle = window.adsbygoogle || []).push({});

My understanding is that when one has a system A in a pure state that interacts with another system B, leading to an entangled state between A and B, the reduced density matrix of the subsystem A will always describe a mixed state, provided that the states of the subsystem B are orthonormal.

If this is correct, the fact that decoherence arises is independent of the number of degrees of freedom of B.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Decoherence and the number of degrees of freedom

**Physics Forums | Science Articles, Homework Help, Discussion**