Real-time path-integral approach for dissipative quantum dot-cavity quantum electrodynamics: impure dephasing-induced...

Area of Science:

• Quantum Optics and Photonics
• Condensed Matter Physics
• Nanoscale Systems

Background:

• Quantum dot (QD)-cavity systems are fundamental for quantum information processing.
• Understanding dissipative effects and coupling regimes is crucial for device performance.
• Longitudinal acoustic (LA) phonons introduce dissipation and dephasing in QD-cavity interactions.

Purpose of the Study:

• To numerically investigate a dissipative quantum dot (QD)-cavity system coupled to a longitudinal acoustic (LA) phonon reservoir.
• To accurately identify and differentiate between weak (WC), strong (SC), and coherent coupling (CC) regimes.
• To develop a method for distinguishing population decay from impure dephasing effects induced by the phonon bath.

Main Methods:

• Employed a numerically exact real-time path-integral approach for simulations.
• Introduced a two-part phenomenological expression to separate population decay and impure dephasing.
• Defined conditions for coherent coupling based on vacuum Rabi splitting (VRS) and peak widths.

Main Results:

• Identified accurate conditions for WC, SC, and CC regimes, with CC requiring VRS larger than the sum of peak widths for clear vacuum Rabi oscillation (VRO).
• The effective population decay rate (emission rate) increases with QD-cavity coupling strength, saturating at the mean of QD and cavity dissipation rates.
• Introduced a quantity to track impure dephasing, revealing its significant contribution to spectral broadening in the SC regime and its reduction in the CC regime.

Conclusions:

• The study provides a robust framework for analyzing dissipative QD-cavity dynamics and distinguishing coupling regimes.
• The proposed phenomenological expression accurately models decay curves and spectra, enabling precise calculation of decay and dephasing rates.
• Effective population decay and impure dephasing rates have distinct roles in spectral peak broadening, dependent on coupling strength and temperature.