Non-Hermitian quantum mechanics and exceptional points in molecular electronics

Area of Science:

• Quantum Mechanics
• Condensed Matter Physics
• Molecular Electronics

Background:

• Non-Hermitian (NH) quantum mechanics explores systems where Hamiltonians may not be Hermitian, leading to complex eigenvalues.
• While NH mathematics is advanced, practical applications in real quantum systems, especially closed systems, remain limited.
• Symmetries in NH operators can guarantee real eigenvalues, crucial for describing physical systems with real energies.

Purpose of the Study:

• To demonstrate the natural emergence of a textbook NH Hamiltonian in modeling molecular electronic devices.
• To analyze the effects of non-Hermiticity and exceptional points on molecular conductance.
• To investigate the spectral density of simple molecule-on-surface models within the NH framework.

Main Methods:

• Utilized a simplified, textbook example of a non-Hermitian Hamiltonian matrix.
• Modeled simple molecular electronic devices and molecules on surfaces.
• Analyzed the spectral properties and conductance influenced by non-Hermitian characteristics.

Main Results:

• The study shows that NH Hamiltonians naturally arise as a simplifying concept in molecular electronic device modeling.
• Consequences of non-Hermiticity and exceptional points on molecular conductance were analyzed.
• The spectral density of molecule-on-surface models was investigated under NH conditions.

Conclusions:

• Non-Hermitian Hamiltonians offer a valuable simplifying framework for understanding molecular electronic devices.
• The presence of non-Hermiticity and exceptional points significantly impacts molecular conductance and spectral properties.
• This work bridges the gap between theoretical NH quantum mechanics and practical applications in molecular electronics.