Continuous monitoring of dynamical systems and master equations

We illustrate the equivalence between the non-unitary evolution of an open quantum system governed by a Markovian master equation and a process of continuous measurements involving this system. We investigate a system of two coupled modes, only one of them interacting with external degrees of freedom, represented, in the first case, by a finite number of harmonic oscillators, and, in the second, by a sequence of atoms where each one interacts with a single mode during a limited time. Two distinct regimes appear, one of them corresponding to a Zeno-like behavior in the limit of large dissipation.

► We illustrate the conjecture that non-unitary evolution can be simulated by continuous measurements.
► The relation between unitary and non-unitary couplings define distinct dynamical regimes.
► One regime with large “dissipation constant” is a Zeno-like behavior.