Quantum feedback-enhanced discord in T-shaped plasmonic waveguides with embedded cavity

Area of Science:

• Quantum optics
• Nanophotonics
• Quantum information science

Background:

• Previous studies explored entanglement in T-shaped waveguides and feedback-enhanced discord in V-shaped waveguides.
• Quantum correlations are crucial for quantum information processing but are susceptible to decoherence.

Purpose of the Study:

• To theoretically investigate a hybrid quantum system combining a T-shaped plasmonic waveguide, a common cavity, and quantum feedback control.
• To enhance and preserve quantum discord between two quantum dots (QDs) within this system.

Main Methods:

• A real-space Hamiltonian approach was used to derive system dynamics.
• The time-independent Schrödinger equation was solved to obtain scattering amplitudes.
• Quantum discord was calculated for the two-QD subsystem using the Wiseman-Milburn formalism for symmetric quantum feedback.

Main Results:

• The T-shaped geometry with active feedback significantly enhances steady-state quantum discord, reaching up to [Formula: see text] for Werner states.
• Three distinct decay regimes for quantum discord were identified.
• System parameters like phase accumulation, cavity-QD couplings, detunings, and dipole-dipole interaction strength offer tunable control over quantum correlations.

Conclusions:

• The hybrid T-shaped plasmonic waveguide system with quantum feedback provides superior control over quantum correlations compared to previous designs.
• This framework enables the design of actively controlled nanophotonic quantum devices for robust quantum information processing at room temperature.
• The study highlights the potential of plasmonic field enhancement and quantum feedback for advanced quantum technologies.