arXiv subjects

Esther Jódar

Publications and source records attributed to Esther Jódar.

7 recordsLinked to original sources

arXiv2026

Scattering matrix elements and energy spectrum of one-dimensional hybrid PT-symmetric finite systems

In this work, we provide a complete description of the scattering matrix elements and electron energy spectrum in one dimensional PT-symmetric hybrid finite systems, using the characteristic determinant approach. We present an analytical formulation of the problem and obtain a closed-form expression for the energy spectrum of the system, consisting of a region of real potential (passive region) surrounded by regions of gain and loss on the left and right, respectively. It has been shown that under certain conditions and a specific ratio between the real and imaginary parts of the complex potentials, it is possible to find analytical expressions for the spectral singularities at which the scattering matrix elements of the hybrid structure tend to infinity at a specific real energy. Within the framework of the same approach, we present a compact analytical expression for the quantization condition that determines the energy spectrum of a model corresponding to the placement of a rigid lattice within a finite-sized box.

cond-mat.mes-hall↗

arXiv2025

Characteristic determinant approach to the spectrum of one-dimensional $\mathcal{P}\mathcal{T}$-symmetric systems

We obtain a closed form expression for the energy spectrum of $\mathcal{P}\mathcal{T}$-symmetric superlattice systems with complex potentials of periodic sets of two $δ$-potentials in the elementary cell. In the presence of periodic gain and loss we analyzed in detail a diatomic crystal model, varying either the scatterer distances or the potential heights. It is shown that at a certain critical value of the imaginary part of the complex amplitude, topological states depending on the lattice size and the configuration of the unit cell can disappear. This may happened at the $\mathcal{PT}$-symmetry breaking (exceptional) points.

cond-mat.mes-hall↗

arXiv2024

Tunneling time in coupled-channel systems

In present work, we present a couple-channel formalism for the description of tunneling time of a quantum particle through a composite compound with multiple energy levels or a complex structure that can be reduced to a quasi-one-dimensional multiple-channel system.

cond-mat.other↗

arXiv2023

Tunneling time and Faraday/Kerr effects in $\mathcal{PT}$-symmetric systems

We review the generalization of tunneling time and anomalous behaviour of Faraday and Kerr rotation angles in parity and time ($\mathcal{P}\mathcal{T}$)-symmetric systems. Similarities of two phenomena are discussed, both exhibit a phase transition-like anomalous behaviour in certain range of model parameters. Anomalous behaviour of tunneling time and Faraday/Kerr angles in $\mathcal{P}\mathcal{T}$-symmetric systems is caused by the motion of poles of scattering amplitudes in energy/frequency complex plane.

cond-mat.other↗

arXiv2023

Tunneling time in $\mathcal{P}\mathcal{T}$-symmetric systems

In the present work we propose a generalization of tunneling time in parity and time ($\mathcal{P}\mathcal{T}$)-symmetric systems. The properties of tunneling time in $\mathcal{P}\mathcal{T}$-symmetric systems are studied with a simple contact interactions periodic finite size diatomic $\mathcal{P}\mathcal{T}$-symmetric model. The physical meaning of negative tunneling time in $\mathcal{P}\mathcal{T}$-symmetric systems and its relation to spectral singularities is discussed.

cond-mat.other↗

arXiv2023

Polar magneto-optic Kerr and Faraday effects in finite periodic \texorpdfstring{$\mathcal{P}\mathcal{T}$}{PT}-symmetric systems

We discuss the anomalous behavior of the Faraday (transmission) and polar Kerr (reflection) rotation angles of the propagating light, in finite periodic parity-time ($\mathcal{P}\mathcal{T}$) symmetric structures, consisting of $N$ cells. The unit cell potential is two complex $δ$-potentials placed on both boundaries of the ordinary dielectric slab. It is shown that, for a given set of parameters describing the system, a phase transition-like anomalous behavior of Faraday and Kerr rotation angles in a parity-time symmetric systems can take place. In the anomalous phase the value of one of the Faraday and Kerr rotation angles can become negative, and both angles suffer from spectral singularities and give a strong enhancement near the singularities. We also shown that the real part of the complex angle of KR, $θ^{R}_1$, is always equal to the $θ^{T}_1$ of FR, no matter what phase the system is in due to the symmetry constraints. The imaginary part of KR angles $θ^{R^{r/l}}_2$ are related to the $θ^{T}_2$ of FR by parity-time symmetry. Calculations based on the approach of the generalized nonperturbative characteristic determinant, which is valid for a layered system with randomly distributed delta potentials, show that the Faraday and Kerr rotation spectrum in such structures has several resonant peaks. Some of them coincide with transmission peaks, providing simultaneous large Faraday and Kerr rotations enhanced by an order one or two of magnitude. We provide a recipe for funding a one-to-one relation in between KR and FR.

physics.optics↗

arXiv2022

Anomalous Faraday effect in a $\mathcal{P}\mathcal{T}$-symmetric dielectric slab

In this letter we discuss a phase transition-like anomalous behavior of Faraday rotation angles in a simple parity-time ($\mathcal{P}\mathcal{T}$) symmetric model with two complex $δ$-potential placed at both boundaries of a regular dielectric slab. In anomalous phase, the value of one of Faraday rotation angles may turn negative, and both angles suffer spectral singularities and yield strong enhancement near singularities.

cond-mat.mes-hall↗