Open quantum system

In physics, an open quantum system is a 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,^[1] 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, quantum measurement theory, quantum statistical mechanics, quantum information science, quantum thermodynamics, quantum cosmology, quantum biology, and semi-classical approximations.

^ Breuer, H.-P.; Petruccione, F. (2007). The Theory of Open Quantum Systems. Oxford University Press. p. vii. Quantum mechanical systems must be considered as open systems

[1] Breuer, H.-P.; Petruccione, F. (2007). The Theory of Open Quantum Systems. Oxford University Press. p. vii. Quantum mechanical systems must be considered as open systems

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