Quantum controlled-phase-flip gate between a flying optical photon and a Rydberg atomic ensemble.

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Optics

Background:

• Quantum networks require robust gates between flying and stationary qubits.
• Existing methods often demand strong single-atom-photon coupling, limiting practicality.

Purpose of the Study:

• To propose a scheme for a quantum controlled-phase-flip (CPF) gate.
• To enable reliable quantum communication between optical photons and atomic ensembles.

Main Methods:

• Utilizing a cavity input-output process with a Rydberg atomic ensemble.
• Employing dark resonance and Rydberg blockade to induce conditional phase shifts on photons.
• Operating in the N-atoms strong-coupling regime.

Main Results:

• Successfully demonstrated a scheme for a quantum controlled-phase-flip (CPF) gate.
• The use of Rydberg blockade significantly relaxes the stringent single-atom strong coupling requirement.
• Achieved conditional phase shift on a flying photon pulse reflected from the cavity.

Conclusions:

• The proposed scheme offers a practical approach for building quantum networks.
• It enhances the feasibility of linking distant quantum computational nodes.
• This work paves the way for more robust quantum information processing and communication.