Non-dynamical quantum trajectories

Ting Yu

In this tutorial, I will review some recent progresses in non-Markovian dynamics of quantum open systems. I will be focused with non-Markovian quantum trajectories and non-Markovian master equation approaches. In particular, I will show how to derive an exact non-Markovian master equation from the corresponding quantum trajectories. I will also show how to use quantum trajectories to derive the well-known Kraus operators for pure dephasing noise. The applications of quantum trajectories to quantum information and decoherence will be briefly reviewed.

Walter T. Strunz, Lajos Diósi, Nicolas Gisin

We present a theory of non-Markovian quantum trajectories that describe the dynamics of a quantum system coupled to an environment of harmonic oscillators. When averaged over the noise, they reproduce the standard reduced density matrix without any approximation, in particular without Markov approximation. The time evolution of the environment can also be determined from these non-Markovian quantum trajectories. We present a simple example to demonstrate the power of our approach. As a remarkable feature of non-Markovian quantum trajectories, we show that for strong coupling to a dissipative environment with memory, the asymptotic state can be reached in a finite time. Further examples are described in the text.

Chengjun Wu, Yang Li, Mingyi Zhu +1 more

Open quantum system interacting with structured environment is important and manifests non- Markovian behavior, which was conventionally studied using quantum trajectory stochastic method. In this paper, by dividing the effects of the environment into two parts, we propose a deterministic method without using quantum trajectory. This method is more efficient and accurate than stochastic method in most Markovian and non-Markovian cases. We also extend this method to the generalized Lindblad master equation.