Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1856185 | Annals of Physics | 2012 | 32 Pages |
We consider the entropy and decoherence in fermionic quantum systems. By making a Gaussian Ansatz for the density operator of a collection of fermions we study statistical 2-point correlators and express the entropy of a system fermion in terms of these correlators. In a simple case when a set of NN thermalised environmental fermionic oscillators interacts bi-linearly with the system fermion we can study its time dependent entropy, which also represents a quantitative measure for decoherence and classicalization. We then consider a relativistic fermionic quantum field theory and take a mass mixing term as a simple model for the Yukawa interaction. It turns out that even in this Gaussian approximation, the fermionic system decoheres quite effectively, such that in a large coupling and high temperature regime the system field approaches the temperature of the environmental fields.
► We construct the Gaussian density operator for relativistic fermionic systems. ► The Gaussian entropy of relativistic fermionic systems is described in terms of 2-point correlators. ► We explicitly show the growth of entropy for fermionic fields mixing with a thermal fermionic environment.