Myungshik Kim (Imperial College London)

Open Quantum Systems

A quantum mechanical system is called open when it interacts with the environment. Most realistic systems are open quantum systems as it is very difficult for them to be completely isolated from the environment. This interaction with the environment will affect the system in a non-negligible way and therefore the study of open quantum systems is a very pertinent topic.

My area of research is on coupled harmonic oscillators. My most recent work was on non-Markovian behaviour (NMB) in open quantum systems, which considers how memory affects system dynamics. By considering models consisting of coupled harmonic oscillators, the aim was to gain a better understanding of NMB and find possible ways to control it.


Affecting Non-Markovian behaviour by changing bath structures


For many open quantum systems, a master equation approach employing the Markov approximation cannot reliably describe the dynamical behaviour. This is the case, for example, in a number of solid state or biological systems, and it has motivated a line of research aimed at quantifying the amount of non-Markovian behaviour in a given model. Within this framework, we investigate the dynamics of a quantum harmonic oscillator linearly coupled to a bosonic bath. We focus on Gaussian states, which are suitably treated using a covariance matrix approach. Concentrating on an entanglement based non-Markovian behaviour quantifier (NMBQ) proposed by Rivas et. al., we consider the role that near resonant and off-resonant modes play in affecting the NMBQ. By using a large but finite bath of oscillators for both Ohmic and super Ohmic spectral densities we find, by systematically increasing the coupling strength, initially the near resonant modes provide the most significant non-Markovian effects, while after a certain threshold of coupling strength the off-resonant modes play the dominant role. We also consider the NMBQ for two other models where we add a single strongly coupled oscillator to the model in extra bath mode and ‘buffer’ configurations, which affects the modes that determine non-Markovian behaviour.


SSUSP 67, Strathclyde (August 2011)

PGR Symposium, Imperial (June 2013)


VCQ, University of Vienna (April 2013)

Hunter College, City University New York (June 2013)

CQT, National University of Singapore (July 2013)

KIAS, Seoul (August 2013)


Quantum mechanics: Real Magic (January 2011)

Big Bang Science Fair (March 2011, March 2013)

Imperial Festival (May 2012, May 2013)

Royal Society Summer Exhibition (July 2013)


Student representative on the student – staff committee (September 2010 - )

Organising committee for QUICC summer school, Aberystwyth (September 2012)