Creating Artificial Quantum Chiral States : Time Evolving Open Spin Chains

University essay from Uppsala universitet/Materialteori

Abstract: The discoveries in applications of chirality in various areas of science seem to never cease to emerge. Chirality, being the property that some objects are geometrically distinguishable from their mirror image, is a tiny difference of vast importance. The fact that multiple biological structures are chiral is what permits life on Earth and its discovery had a severe impact on medical development. When the concept of quantum chirality was introduced, the connection between the chiral symmetry and the quantum states and operators that characterize quantum chirality was not particularly clear. It was shown that closed spin chains of an odd number of spins naturally had chiral states as eigenstates of a Hamiltonian describing Heisenberg and Dzyaloshinsky-Moriya (DM) interactions, and the symmetry of the system in direct relation to the chiral symmetry of the eigenstates quickly became of interest. The aim of this thesis is therefore to explore how quantum chirality is a chiral symmetry and to develop a scheme to create chiral states from systems that lack the required symmetry. The investigation showed that discretized probability current gives a good explanation to why the chiral states follow a chiral nature, but further examination is required in order to generalize a deeper connection between the probability current and the chiral states of spin chains. The results also indicated that it was possible to force open spin chains into purely chiral states, and into superpositions thereof, by time evolution. The scheme is still in its early stage and physical implementation and applications are yet to be explored.

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