Quantum and Classical Exceptional Points at the Nanoscale: Properties and Applications

Area of Science:

• Non-Hermitian physics
• Quantum mechanics
• Quantum optics

Background:

• Exceptional points (EPs) are spectral singularities in non-Hermitian systems, arising from environmental energy exchange.
• EPs in classical systems have seen significant application, but quantum implementations face challenges with tuning, stability, and noise.
• This review focuses on quantum EPs and their observable quantum effects.

Purpose of the Study:

• To summarize current research and opportunities in quantum exceptional points (EPs).
• To introduce Hamiltonian and Liouvillian EPs in the quantum regime and discuss their properties related to quantum jumps and decoherence.
• To provide insights into accessing EPs in quantum systems and their applications, particularly in quantum optics and nanoscale devices.

Main Methods:

• Review of theoretical and experimental advances in accessing quantum EPs.
• Discussion of EP-based quantum-optics applications using state-of-the-art technologies.
• Analysis of challenges in constructing nanoscale quantum EPs.

Main Results:

• Introduction of Hamiltonian and Liouvillian EPs and their distinct quantum properties.
• Comprehensive overview of theoretical and experimental progress in accessing quantum EPs across various platforms.
• Highlighting of EP-based quantum-optics applications and nanoscale challenges.

Conclusions:

• Quantum EPs present significant opportunities for controlling quantum dynamics and properties.
• Further research is needed to overcome challenges in stability, noise, and nanoscale implementation.
• Quantum EPs hold promise for advancing fundamental science and developing high-performance quantum devices.