Editing Open quantum system (section)

{{Use American English|date=January 2019}}{{Short description|Quantum mechanical system that interacts with a quantum-mechanical environment}}
{{In line citation|date=January 2019}}
In [[physics]], an '''open quantum system''' is a [[Quantum mechanics|quantum]]-mechanical system that interacts with an external [[quantum system]], which is known as the ''environment'' or a ''bath''. In general, these interactions significantly change the dynamics of the system and result in [[quantum dissipation]], such that the information contained in the system is lost to its environment. Because no quantum system is completely isolated from its surroundings,<ref>{{cite book |first1=H.-P. |last1=Breuer |first2=F. |last2=Petruccione |title=The Theory of Open Quantum Systems |publisher=Oxford University Press |date=2007 |page=vii |quote="Quantum mechanical systems must be considered as open systems"}}</ref> it is important to develop a theoretical framework for treating these interactions in order to obtain an accurate understanding of quantum systems.

Techniques developed in the context of open quantum systems have proven powerful in fields such as [[quantum optics]], [[Measurement in quantum mechanics|quantum measurement theory]], quantum [[statistical mechanics]], [[quantum information]] science, [[quantum thermodynamics]], [[quantum cosmology]], [[quantum biology]], and semi-classical approximations.