Structure of the Hamiltonian of mean force

Understand

The Hamiltonian of mean force is an effective Hamiltonian that allows a quantum system, non-weakly coupled to an environment, to be written in an effective Gibbs state.

• We present results on the structure of the Hamiltonian of mean force in extended quantum systems with local interactions.
• We show that its spatial structure exhibits a ``skin effect'' -- its difference from the system Hamiltonian dies off exponentially with distance from the system-environment boundary.
• For spin systems, we identify the terms that can appear in the Hamiltonian of mean force at different orders in the inverse temperature.