Robust Quantum Memory in a Trapped-Ion Quantum Network Node

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Networking

Background:

• Trapped-ion systems are promising for quantum information processing.
• Efficient quantum memory is crucial for scalable quantum networks.
• Integrating different ion species presents unique challenges.

Purpose of the Study:

• To create a mixed-species trapped-ion quantum network node.
• To demonstrate long-lived quantum memory using a robust qubit.
• To improve the fidelity and duration of ion-photon entanglement.

Main Methods:

• Integrating a long-lived memory qubit (43Ca+) into a mixed-species trapped-ion node.
• Generating and transferring ion-photon entanglement between network qubits (88Sr+ and 43Ca+).
• Utilizing quantum state tomography and dynamical decoupling techniques.

Main Results:

• Achieved high-fidelity entanglement transfer (0.977(7)) to a memory qubit.
• Demonstrated entanglement storage with a decay rate ~70 times slower compared to direct ion-photon entanglement.
• Maintained high ion-photon entanglement fidelity (0.81(4)) after 10 seconds using dynamical decoupling.

Conclusions:

• The developed quantum network node architecture enables robust, long-lived quantum memory.
• This integration of memory qubits significantly enhances the potential for scalable quantum networks.
• The results pave the way for more stable and efficient quantum communication protocols.