Lopsided optical diffraction in a loop electromagnetically induced grating.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Optics
• Non-Hermitian Physics

Background:

• Cold atomic ensembles offer a versatile platform for simulating complex physical phenomena.
• Non-Hermitian optical structures are crucial for developing advanced optical devices with tailored responses.
• Parity-time (PT) symmetry and antisymmetry (APT) provide unique pathways for controlling light propagation.

Purpose of the Study:

• To propose a theoretical scheme for realizing a lopsided optical diffraction grating in a cold ⁸⁷Rb atomic ensemble.
• To investigate the switching between PT symmetric and APT modulation using phase adjustments.
• To explore the robustness of PT symmetry and antisymmetry against coupling field amplitudes.

Main Methods:

• Utilizing a cold rubidium-87 (⁸⁷Rb) atomic ensemble.
• Implementing a non-Hermitian optical structure with a lopsided optical diffraction grating.
• Employing a single spatially periodic modulation combined with loop-phase.
• Adjusting relative phases of applied beams to switch between PT and APT modulation.

Main Results:

• Demonstration of a lopsided optical diffraction grating.
• Achieved robust PT symmetry and APT modulation, insensitive to coupling field amplitudes.
• Observed nontrivial optical properties including lopsided diffraction, single-order diffraction, and asymmetric Dammam-like diffraction.

Conclusions:

• The proposed scheme offers precise modulation of optical response without symmetry breaking.
• This work paves the way for versatile non-Hermitian and asymmetric optical devices.
• The findings contribute to the fundamental understanding of light-matter interactions in non-Hermitian systems.