摘要: This chapter provides a brief introduction to quantum systems that are coupled large reservoirs. It aims remind the reader of well-known concepts necessary for understanding book and does not claim provide self-contained introduction. starts with summary conventions used in then introduces master equations some examples. also requires us introduce density matrix: among other things, we discuss its evolution closed system under measurements. To connect system-reservoir theories, review definition tensor product partial trace. Finally, Lindblad form equation properties before closing remarks on superoperator representation equations.