Efficient generation of entangled multiphoton graph states from a single atom.

Area of Science:

• Quantum science and technology
• Quantum information processing
• Photonic entanglement

Background:

• Quantum effects like entanglement are key for quantum computing, communication, and sensing.
• Scalability challenges exist due to decoherence and probabilistic entanglement generation methods.
• Optical photons are ideal qubit carriers due to their robustness and manipulability.

Purpose of the Study:

• To implement a deterministic protocol for generating photonic entanglement.
• To overcome the limitations of probabilistic entanglement generation.
• To create large-scale entangled states for quantum applications.

Main Methods:

• Utilizing a single memory atom in an optical cavity.
• Interleaving controlled single-photon emissions with atomic qubit rotations.
• Employing a deterministic protocol for entanglement generation.

Main Results:

• Successfully generated Greenberger-Horne-Zeilinger (GHZ) states of up to 14 photons and linear cluster states of up to 12 photons.
• Achieved fidelities of 76(6)% for GHZ states and 56(4)% for cluster states.
• Demonstrated a high source-to-detection efficiency (43.18(7)%) enabling measurement of large states approximately once per minute.

Conclusions:

• The deterministic protocol overcomes scalability limitations of probabilistic methods.
• The rapid generation rate of large entangled states is orders of magnitude faster than previous experiments.
• This work paves the way for scalable measurement-based quantum computation and communication.