Rydberg Atom Entanglements in the Weak Coupling Regime.

Area of Science:

• Quantum physics
• Atomic physics
• Quantum information science

Background:

• Rydberg atoms are highly sensitive to external fields, making them promising for quantum applications.
• Controlled entanglement of multiple atoms is crucial for advancing quantum computing and simulation.
• Existing entanglement schemes face limitations in scalability and control over inter-atomic distances.

Purpose of the Study:

• To propose and experimentally demonstrate a novel entanglement scheme for Rydberg atoms.
• To achieve controlled phase operations between atoms beyond the standard Rydberg blockade distance.
• To explore complex entanglement structures, including multi-atom states and counterintuitive scenarios.

Main Methods:

• Utilizing the van der Waals interaction phase induced by Ramsey-type pulsed interactions.
• Employing single rubidium atoms confined in optical tweezer dipole traps for experimental control.
• Implementing a scheme that allows entanglement generation even with partially blockaded atoms.

Main Results:

• Demonstrated controlled phase operations between Rydberg atoms separated by distances exceeding the blockade radius.
• Generated various entanglement states, including two-atom entanglement with a nearby third atom.
• Successfully produced W-states for three partially blockaded atoms.
• Achieved an experimental entanglement fidelity of F=0.59±0.11 for the proposed scheme.

Conclusions:

• The proposed entanglement scheme offers a versatile and robust method for generating complex quantum states with Rydberg atoms.
• The technique overcomes limitations of traditional Rydberg blockade, enabling entanglement over larger distances and in challenging multi-atom configurations.
• Experimental validation with rubidium atoms confirms the feasibility and effectiveness of the entanglement strategy, paving the way for advanced quantum technologies.