Characterizing quantum measurement through environmental stochastic entropy production in a two-spin-1/2 system

Quantum state diffusion is a framework within which measurement may be described as the continuous and gradual collapse of a quantum system to an eigenstate as a result of interaction with its environment. The irreversible nature of the quantum trajectories that arise may be characterized by the environmental stochastic entropy production associated with the measurement. We consider a system of two spin-1/2 particles undergoing either single-particle measurements or measurements of the total <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>z</a:mi></a:math>-spin component <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>S</b:mi><b:mi>z</b:mi></b:msub></b:math>. The mean asymptotic rates of environmental stochastic entropy production associated with collapse can depend on the eigenstate of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>S</c:mi><c:mi>z</c:mi></c:msub></c:math> selected and on the initial state of the system, offering an additional avenue for characterizing quantum measurement.