Non-Hermitian degeneracies and unidirectional reflectionless atomic lattices

Area of Science:

• Atomic physics
• Quantum optics
• Non-Hermitian physics

Background:

• Light propagation in optical lattices is crucial for quantum technologies.
• Non-Hermitian systems offer unique light manipulation possibilities.
• Controlling light-matter interactions in driven cold atoms is an active research area.

Purpose of the Study:

• To investigate light propagation in optical lattices of driven cold atoms.
• To identify conditions for unidirectional reflectionless light propagation.
• To explore the role of non-Hermitian degeneracies in this process.

Main Methods:

• Theoretical analysis using transfer-matrix calculations.
• Coupled-mode analysis to explain the underlying physics.
• Manipulation of first-order modulation amplitudes of probe susceptibility.

Main Results:

• Observed complete unidirectional reflectionless light propagation at specific non-Hermitian degeneracies.
• Demonstrated that this phenomenon occurs strictly without optical gain.
• Showcased the tunability and reversibility of the effect.

Conclusions:

• Balanced modulation of real and imaginary probe susceptibility leads to unique light propagation.
• Non-Hermitian degeneracies provide a pathway to control light transport in optical lattices.
• The demonstrated effect offers potential for novel optical devices and quantum information processing.