Waveguide Quantum Optomechanics: Parity-Time Phase Transitions in Ultrastrong Coupling Regime

Area of Science:

• Quantum physics
• Optomechanics
• Quantum electrodynamics

Background:

• Waveguide quantum electrodynamics (QED) explores light-matter interactions in confined photonic structures.
• Mechanical oscillations of quantum systems can induce novel phenomena.
• Understanding interaction-induced effects is crucial for quantum technologies.

Purpose of the Study:

• To develop a theoretical framework for interaction-induced phenomena in waveguide QED driven by mechanical qubit oscillations.
• To investigate the possibility of achieving ultrastrong coupling in a simplified two-qubit system.
• To explore the emergence of parity-time (PT) symmetry in such quantum systems.

Main Methods:

• Development of a rigorous theoretical framework.
• Analysis of a system with two harmonically trapped qubits over an optical waveguide.
• Investigation of quantum optomechanical interaction regimes.
• Study of the interplay between open system dynamics and strong coupling.

Main Results:

• Prediction of the ultrastrong coupling regime for quantum optomechanical interaction.
• Emergence of parity-time (PT) symmetry due to the open nature and strong coupling.
• The PT phase transition drives long-living subradiant states.
• These phenomena are observable in state-of-the-art waveguide QED setups.

Conclusions:

• The proposed system provides a novel platform for studying interaction-induced phenomena.
• Emergent PT symmetry in a purely quantum system without artificial gain/loss is demonstrated.
• The findings offer new avenues for controlling quantum states and developing quantum devices.