No physical system is truly isolated. An open quantum system is a quantum system whose dynamics are determined both by interactions internal to the system and by influences from an environment. Markovian behaviour arises when the environment is essentially "memory-less", leading, roughly speaking, to exponential decay of the quantities involved. The non-Markovian case is much less well understood, but is becoming increasingly relevant as our ability to control quantum systems experimentally develops.
Non-Markovian behavior is encountered in many areas of condensed matter physics. An example is a quantum dot coupled to a spin bath. Error correction in quantum computing, implemented using quantum dots or otherwise, may not be adequately handled by assuming that the errors are Markovian. In order to model and understand quantum systems in tailored and finite environments and at short time scales we need an understanding of non-Markovian effects. Experimental progress is rapid, e.g. in the field of quantum control, and makes this an increasingly relevant objective.
Open physical systems, that is, systems coupled to an environment, are described using master equations. Master equations have been extensively used to describe phenomena in condensed matter systems ranging from semiconductor and spin physics to a quantum mechanical description of Brownian motion. At the moment, however, it is not even known what a non-Markovian master equation should look like in general in order to be compatible with physical time evolution. This project will investigate the derivation and use of non-Markovian master equations to describe quantum systems in condensed matter physics.
Please send inquiry emails to Prof. Erika Andersson at E.Andersson@hw.ac.uk