'Order amidst Disorder' in 2D, 3D, and 2D+3D Quantum Dragon Nanodevices
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Quantum effects in nanodevices can lead to unexpected physical properties. The electrical conductance of a nanodevice connected to leads, according to Landauer, is a function of the electron transmission T(E) at energy E, obtained from the solution of the appropriate Schrödinger equation. If a nanodevice has complete electron transmission T(E)=1 for all energies E of the incoming electron, the electrical conductance is infinite in four-probe measurements, and equal to the quantum of conductance, G0, in two-probe measurements. Pure systems (no disorder) which have T(E)=1 are said to exhibit ballistic transport, and this quantum property is utilized in carbon nanotube and graphene-based devices from FETs to qubits. Disorder is disruptive to coherent electron transport due to scattering. Nevertheless, model nano-devices with strong disorder with T(E)=1 exist, which we call quantum dragons [1,2]. We show for carbon-based nanodevices with arbitrarily strong disorder, as well as for other disordered 2D, 3D, and 2D+3D nanodevices, it is possible to have T(E)=1 for all E. Furthermore, even with only short-range correlations among the disorder parameters these strongly disordered devices have at least one non-localized state, demonstrating ‘order amidst disorder’ [3]. We predict carbon-based quantum dragons can have very strange shapes, be strongly disordered, be very tatty, and still exhibit ‘order amidst disorder’. A number of both carbon-based and other quantum dragon nanodevices will be described, as well as instances where small deviations cause related nanosystems to be almost quantum dragon nanodevices.
[1] M.A. Novotny, Energy-independent total quantum transmission of electrons through nanodevices with correlated disorder, Physical Review B 90, 165103, 14 pages (2014).
[2] G. Inkoom and M.A. Novotny, Quantum dragon solutions for electron transport through nanostructures based on rectangular graphs, J. Phys. Commun. 2, 115019 (2018).
[3] M.A. Novotny and T. Novotný, Order amidst disorder in semi-regular, tatty, and atypical random nanodevices with locally correlated disorder, arXiv:2007:01051 (2020).
Figure Caption: Three examples of quantum dragon nanodevices. All have only locally correlated disorder, and all have T(E)=1 for all E which propagate through proper leads as well as exhibiting ‘order amidst disorder’. (a) is based on a 3D graph, (b) and (c) are based on carbon structures.
Dr. Mark Novotny is a Professor and Head of the Department of Physics & Astronomy at Mississippi State University.
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