Quantum Environments: Spin Baths, Oscillator Baths, and applications to Quantum Magnetism

摘要

The low-energy physics of systems coupled to their surroundings is understoodby truncating to effective Hamiltonians; these tend to reduce to a fewcanonical forms, involving coupling to "baths" of oscillators or spins. Themethod for doing this is demonstrated using examples from magnetism,superconductivity, and measurement theory, as is the way one then solves forthe low-energy dynamics. Finally, detailed application is given to the excitingrecent Quantum relaxation and tunneling work in naomagnets.