Generation of a Maximally Entangled State Using Collective Optical Pumping.

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Optics

Background:

• Generating entangled quantum states is crucial for quantum computing and communication.
• Dissipative pumping offers a promising route for state preparation in quantum systems.
• Previous methods for creating entangled states often face challenges with fidelity and scalability.

Purpose of the Study:

• To propose and implement a novel dissipative pumping scheme for creating a singlet Bell state with two qubits.
• To deterministically entangle two trapped calcium-40 ions using this new method.
• To analyze the scheme's performance, fidelity, and sensitivity to noise.

Main Methods:

• Collective optical pumping to an excited energy level.
• Utilizing selective coupling of all states except the singlet Bell state to the excited level.
• Applying the scheme to two trapped ^{40}Ca^{+} ions.

Main Results:

• Achieved 83(1)% singlet fidelity from an initially separable state within 16 pumping cycles.
• Converged initial states with ⪆70% fidelity to 93(1)% singlet fidelity.
• Theoretical analysis demonstrated robustness against common experimental noise sources.

Conclusions:

• The proposed dissipative pumping scheme enables high-fidelity, deterministic generation of singlet Bell states.
• The method is robust and suitable for experimental implementation with trapped ions.
• This work advances the creation of entangled states for quantum information processing.