TCM
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Adam Smith

 Adam Smith

Adam Smith

Member of St Catharine's College
PhD student in Dr Kovrizhin's group

Office: 526 Mott Bld
Phone: +44(0)1223 3 36073
Email: as2457 @ cam.ac.uk

TCM Group, Cavendish Laboratory
19 JJ Thomson Avenue,
Cambridge, CB3 0HE UK.

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Research

I am a condensed matter theorist interested in non-equilibrium quantum systems. My recent work has been on non-equilibrium dynamics of 3D Kitaev quantum spin-liquids (QSLs). We have been able to calculate the dynamical structure factor for a range of lattices with low-energy density of states spanning those possible in 3D. The dynamical structure factor is measurable in inelastic neutron scattering (INS) experiments and our results suggest INS as the spectroscopy of choice to illuminate the physics of Majorana fermions in Kitaev QSLs

So far all candidate materials eventually form a long-range magnetically ordered state at low temperatures and in a strict sense do not realise Kitaev QSL ground states. There is, however, growing evidence that features of the spectroscopic experiments can still be interpreted in terms of the fractionalized excitations of the unperturbed Kitaev model. One goal of my research is to develop an understanding of Kitaev models with additional interactions and at finite temperatures.
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In Plain English

Non-equilibrium behaviour is ubiquitous in nature but its theoretical understanding can be extremely complicated. The reason it is so difficult to make progress far from equilibrium is that a lot of the tools available in equilibrium (or close to) are no longer valid. However, the importance of non-equilibrium phenomena in condensed matter physics is particularly evident in scattering experiments. These are cases when we purposefully kick a system away from equilibrium by firing particles at it. The response can reveal information about the dispersion and dynamics of excitations. I have been studying the scattering response in the context of the Kitaev model which can be mapped to a true non-equilibrium problem.

The Kitaev model is an exactly solvable model which has quantum spin-liquid (QSL) ground states. A QSL has no long-range magnetic order right down to zero temperature, in contrast to conventional magnetic systems. It also hosts fractionalised excitations, that is, collective excitations that cannot be described by a microscopic combination of the underlying degrees of freedom of the system. In particular, the Kitaev models hosts Majorana fermion quasi-particles, which are very difficult to measure directly. Our work reveals that evidence of Majorana physics should be observable in INS experiments.