Entanglement Purification and Protection in a Superconducting Quantum Network

Area of Science:

• Quantum Information Science
• Quantum Communication
• Superconducting Quantum Computing

Background:

• High-fidelity quantum entanglement is crucial for quantum communication and distributed quantum computing.
• Decoherence in communication channels degrades entanglement fidelity, increasing error rates in quantum protocols.
• Entanglement purification is a method to improve the quality of entangled quantum states.

Purpose of the Study:

• To demonstrate entanglement purification of Bell pairs between remote superconducting quantum nodes.
• To correct amplitude damping errors in a superconducting communication cable.
• To protect entangled states from local noise using dynamical decoupling and Rabi driving.

Main Methods:

• Entanglement purification protocol applied to Bell pairs shared between two superconducting quantum nodes.
• Utilized a 1-meter superconducting communication cable with moderate loss.
• Employed dynamical decoupling and Rabi driving techniques for noise protection.

Main Results:

• Achieved fractional increases in entanglement fidelity up to 25% for higher damping errors.
• Reached a best final fidelity of 94.09±0.98% after purification.
• Increased effective qubit dephasing time by a factor of 4 (from 3 to 12 μs) using noise protection methods.

Conclusions:

• Entanglement purification effectively corrects amplitude damping errors in superconducting quantum networks.
• Dynamical decoupling and Rabi driving enhance the preservation of entangled states against local noise.
• Demonstrated the potential for generating and maintaining high-fidelity entanglement in superconducting quantum communication networks.