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Department of Physics
(+612) 9850 8913
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Research
My research activities are principally concerned with the properties of open quantum systems, in particular non-Markovian systems, the use of the quantum trajectory method, quantum measurement theory, and quantum Brownian motion.
In more detail, the problems of current interest are as follows:
- Formulating a theory of quantum Brownian motion based on a
quantum measurement perspective in which the collisions of the
Brownian particle with particles making up its surrounding
environment are considered to be imperfect, simultaneous
measurements of the position and the momentum of the Brownian
particle;
- Attempting to establish a correspondence between the Lindblad
form of a Markovian master equation as derived from an open system
description of a system coupled to an environment, and the
structure that emerges if use is made of the ideas of generalized
measurements as being processes by which information is gained
about a system. The former description is a purely physical model
of a system-environment interaction, and yet a meaningful
measurement interpretation can be associated with it, while the
latter is directly formulated in terms of a change in our
knowledge of the state of a system conditioned on the results
gained by direct measurement. This work is being done in
collaboration with Stephen Barnett, John Jeffers at
the University of Strathclyde and David Pegg at Griffith
University, Brisbane;
- Using a quantum trajectory technique to derive the general
master equation of a system subject to white noise. The
formulation makes it possible to carry this out even in situations
in which the white noise enters in a non-linear fashion. The
particular application of these ideas is to atoms in a harmonic
trap subject to noise. This work is being done in collaboration
with Krzysztof Wòdkiewicz at the University of Warsaw;
- Using the properties of completely positive maps to try to
derive general properties of non-Markovian master
equations;
- Making use of non-linear time transformations to reduce
certain classes of non-Markovian master equations to a Markovian
form. This method is being developed so as to formulate means of
simulating these non-Markovian equation by quantum trajectory
methods.