Conductance through a single impurity in the metallic zigzag carbon nanotube

We investigate transport through a single impurity in metallic zigzag carbon nanotube and find the conductance sensitively depends on the impurity strength and the bias voltage. It is rather interesting that interplay between the current-carrying scattering state and evanescent modes leads to rich phenomena including resonant backward scattering, perfect tunneling and charge accumulations. In addition, we also find a dual relation between the backscattered conductance and the charge accumulation. At the end, relevance to the experiments is discussed.Comment: 3 pages, 3 figure

Relating non-Hermitian and Hermitian quantum systems at criticality

We demonstrate three types of transformations that relate Hermitian and non-Hermitian quantum systems at criticality which can be described by conformal field theories (CFTs). For the transformation preserving both the physical spectrum (PS) and the entanglement spectrum (ES), the corresponding central charges extracted from the logarithmic scaling of the entanglement entropy are identical for both Hermitian and non-Hermitian systems. The second transformation preserves the PS but not the ES. The entanglement entropy scalings are different and lead to different central charges. We demonstrate this transformation by the dilation method for the free fermion cases, where the non-Hermitian system with central charge $c=-2$ can be mapped to the Hermitian system with $c=1$. Lastly, we study the Galois conjugation in the Fibonacci model with parameter $\phi \to -1/\phi$, in which the transformation does not preserve both PS and ES. We demonstrate the Fibonacci model and its Galois conjugation relate the tricritical Ising model/3-state Potts model and the Lee-Yang model with negative central charges from the scaling property of the entanglement entropy.Comment: 6 pages, 4 figures, comments are welcom