Dr. Andrew Mitchell

I am a postdoc in the Condensed Matter Theory group at Oxford University, and a Junior Research Fellow at Wadham College. I work primarily in the research group of Prof. David Logan in Oxford, and have strong collaborative ties with the Institute of Theoretical Physics at the University of Cologne.

My research interests are broadly in the area of condensed matter science, with a particular emphasis on many-body theory and strongly-correlated electron systems. A wide range of systems fall into this category --- from materials such as superconductors, to nanotechnology devices such as quantum dots, nanotubes, and molecular electronics. Since strongly-correlated condensed matter systems occupy a central position in modern physics and chemistry, a fundamental theoretical understanding of them is essential.

Exact treatment of systems with ~1023 interacting particles is (in most cases) impossible, and mean field approaches often fail to capture the fundamental physics when electron-electron interactions are strong. A classic example is in the so-called Kondo effect: a single magnetic impurity embedded in a metal generates highly non-trivial physical behaviour at low temperatures due to scattering of itinerant conduction electrons off a localized quantum spin. Sophisticated analytical and numerical tools are required to treat such problems, which are inherently non-perturbative and inescapably many-body.

The fascinating physics of the Kondo effect has recently appeared in semiconductor 'quantum dot' devices, which behave as highly-tunable artificial atoms hybridized with metallic 'leads'. Likewise, coupled quantum dot devices are regarded as artificial molecules, and hence simulate components of molecular electronics. The interplay between spin and orbital degrees of freedom with electron interactions and many-body effects, leads to a much richer range of physical behaviour and potential applications.

Interestingly, generalized quantum impurity problems also appear as effective local models within 'dynamical mean field theory' (DMFT) for correlated lattice problems. Thus, understanding the fundamental physics associated with strong electron interactions in mesoscopic quantum impurity systems is of key importance. The development of analytical and numerical theoretical tools to tackle such problems is the focus of my current research.

For a detailed description of my research interests and projects, see the 'Research' page.
For a full list of my publications, see the 'Publications' page.

Recent publications:

Multi-band quantum impurity problems: Phys. Rev. B 89, 121105(R) (2014)
Majorana fermions and topological Kondo effect: Phys. Rev. B 89, 045143 (2014)
Powerlaw Kondo: Phys. Rev. B 88, 195119 (2013) -- Editor's Suggestion
Graphene: Phys. Rev. B 88, 075104 (2013)
Triple quantum dots: J. Phys. Chem. B 117, 12777 (2013)
Topological insulators: Phys. Rev. B 87, 075430 (2013)

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