Efficient cavity-assisted storage of photonic qubits in a solid-state quantum memory

Area of Science:

• Quantum Information Science
• Solid-State Physics
• Quantum Optics

Background:

• Quantum memories are crucial for quantum communication and computation.
• Solid-state systems offer robust platforms for quantum information processing.
• Cavity enhancement can significantly improve the performance of quantum memories.

Purpose of the Study:

• To demonstrate high-efficiency storage and retrieval of weak coherent optical pulses and photonic qubits.
• To investigate the role of cavity enhancement in a solid-state quantum memory.
• To achieve efficient storage of time-bin qubits using an atomic frequency comb scheme.

Main Methods:

• Utilized an atomic frequency comb (AFC) memory in a Pr3+:Y2SiO5 crystal.
• Embedded the crystal within an impedance-matched cavity.
• Stored weak coherent pulses at the single-photon level and time-bin qubits.

Main Results:

• Achieved up to 62% storage efficiency for weak coherent pulses at the single-photon level with a 2 µs storage time.
• Demonstrated enhanced efficiency for longer storage times up to 70 µs due to cavity enhancement.
• Stored weak coherent time-bin qubits with a record 51 ± 2% efficiency and >94.8% fidelity.

Conclusions:

• The cavity-enhanced AFC quantum memory in Pr3+:Y2SiO5 provides high-efficiency storage and retrieval of optical pulses and photonic qubits.
• Impedance matching of the cavity is critical for enhancing storage efficiency, especially for longer durations.
• The demonstrated performance, though limited by qubit creation/measurement imperfections, represents a significant advancement in solid-state quantum memory capabilities.