Speaker
Description
We discuss the derivation of Gaussian non-Markovian quantum stochastic master equations using the technique of the Keldysh contour. First, we derive a general expression for the dynamics of a quantum system in contact with a Gaussian environment. Then, we use it to re-derive the stochastic von Neumann equation: our approach clarifies that the two noises characterizing such equation can be interpreted as a single complex stochastic field defined on the Keldysh contour.
Moreover, we show how such a noise can be reduced to a physical-time one at the price of turning the master equation into a convolution equation, similarly to non-Markovian quantum diffusion equations.
Contrary to existing approaches, our equation is however described by a real noise instead of a complex one. The insight offered by our method is also used to envision a semiclassical scenario in which the noise can be interpreted in terms of a measurement process upon the environment.
