Equivalent electrical multiport for quantum systems in entangled states

This paper introduces the concept of equivalent electrical multiport for a quantum device made of a pair of two-level objects, coupled via entanglement. The coupled pair is described in terms of an equivalent 2×2 admittance matrix, derived from the theory of the generalized susceptibility. This result provides a valuable tool to analyze quantum circuits in the frame of the classical circuit theory. The study of the properties of the admittance matrix highlights the effect of a new coupling mechanism, due to entanglement, which adds to the classical electromagnetic coupling.