All-optical quantum information processing via a single-step Rydberg blockade gate

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Computing

Background:

• Deterministic two-photon gates are essential for building a quantum internet.
• A CZ photonic gate is crucial for universal all-optical quantum information processing.
• Previous schemes faced limitations due to environmental noise and experimental complexity.

Purpose of the Study:

• To propose a novel approach for realizing a high-fidelity CZ photonic gate.
• To enhance the robustness of quantum operations against environmental decoherence.
• To simplify experimental realization for practical quantum network applications.

Main Methods:

• Storing photons in an atomic ensemble via non-Rydberg electromagnetically induced transparency (EIT).
• Implementing a fast, single-step Rydberg excitation with global lasers and relative intensity modulation.
• Utilizing continuous laser protection to shield Rydberg atoms from environmental noise.

Main Results:

• Achieved a high-fidelity CZ photonic gate operation.
• Demonstrated continuous laser protection, mitigating decoherence from spontaneous emission and Doppler broadening.
• Optimized optical depth and simplified experimental setup through complete spatial overlap of photons within the blockade radius.
• Projected a fidelity of 99.7% with realistic experimental parameters.

Conclusions:

• The proposed scheme offers a robust and high-fidelity CZ photonic gate for quantum internet realization.
• Continuous laser protection and optimized photon storage circumvent limitations of previous Rydberg EIT schemes.
• The method simplifies experimental complexity while maintaining high operational fidelity.