The Gaussian entropy of fermionic systems

作者：Prokopec Tomislav; Schmidt Michael G; Weenink Jan^*

来源：Annals of Physics, 2012, 327(12): 3138-3169.

DOI：10.1016/j.aop.2012.09.003

• Entropy
• Decoherence
• Non-equilibrium quantum field theory

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 N 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.

• 出版日期2012-12