Effect of geometrical rotation on conductance fluctuations in graphene quantum dots

Conductance fluctuations are ubiquitous in quantum transport through nanoscale devices, and how to modulate or control the fluctuation patterns is of considerable interest. We use two-terminal graphene devices as a prototypical system and articulate a scheme based on geometrical rotation of the device to effectively modulate the conductance fluctuations. To facilitate a systematic calculation of the conductance as a function of the Fermi energy and the rotation angle, we use a layer-by-layer based, recursive non-equilibrium Green's function approach, which is demonstrated to be computationally extremely efficient. Our study indicates that relative rotation of the device, which is experimentally feasible, can markedly affect the degree of conductance fluctuations, and we provide physical explanations of this behavior based on the emergence of edge states.