Finite-Size Effects in Quantum Metrology at Strong Coupling: Microscopic vs Phenomenological Approaches
The study investigates precision limits for a spin chain strongly coupled to a heat bath, comparing microscopic and phenomenological methods. It shows that ignoring finite-size effects causes errors, and strong coupling has specific advantages for thermometry at low temperatures. The findings establish a consistent framework for evaluating quantum metrology in realistic, finite devices beyond the weak-coupling limit.