Phonon-mediated quantum state transfer and remote qubit entanglement.

Area of Science:

• Quantum physics
• Solid-state quantum systems
• Acoustic quantum communication

Background:

• Phonons, especially surface acoustic wave (SAW) phonons, are proposed for coherent coupling of distant solid-state quantum systems.
• Superconducting qubits can control and detect individual phonons, enabling generation and measurement of complex phonon states.

Purpose of the Study:

• To deterministically emit and capture itinerant SAW phonons.
• To enable quantum entanglement of two superconducting qubits using phonons as a communication channel.

Main Methods:

• Utilized a 2-millimeter acoustic quantum communication channel (500-nanosecond delay line).
• Demonstrated phonon emission and recapture by a superconducting qubit.
• Implemented partial phonon transfer for quantum state transfer and entanglement generation.

Main Results:

• Achieved quantum state transfer between two superconducting qubits with 67% efficiency.
• Generated an entangled Bell pair with 84% fidelity through partial phonon transfer.
• Successfully demonstrated deterministic phonon emission and capture.

Conclusions:

• Surface acoustic wave phonons can be deterministically controlled and utilized for quantum information transfer.
• Phonon-mediated coupling provides a promising avenue for entangling distant solid-state qubits.
• This work establishes phonons as a robust quantum communication channel for scalable quantum networks.