Incoherent-mediator for quantum state transfer in the ultrastrong coupling regime.

Area of Science:

• Quantum physics
• Quantum information science
• Optics and photonics

Background:

• Quantum state transfer is crucial for quantum computing and communication.
• Ultrastrong light-matter coupling presents challenges for maintaining quantum coherence.
• Thermal population in quantum systems typically degrades performance.

Purpose of the Study:

• To investigate quantum state transfer between two qubits via a common quantum bus.
• To explore the feasibility of high-fidelity operations in the presence of thermal noise.
• To propose a practical implementation in circuit Quantum Electrodynamics (QED).

Main Methods:

• Utilizing an ultrastrong coupled light-matter system as a quantum bus.
• Resonating qubit frequencies with a forbidden transition in the mediating system.
• Analyzing the system within the framework of the multimode Dicke model.

Main Results:

• Achieved high-fidelity quantum state transfer (swap operation) between two qubits.
• Demonstrated robustness against thermal population in the quantum bus.
• Identified a realistic circuit QED implementation.

Conclusions:

• High-fidelity quantum state transfer is possible even with a thermally populated quantum bus in the ultrastrong coupling regime.
• The proposed method offers a pathway for hot quantum information processing.
• This work advances the understanding of light-matter interactions in quantum technologies.