Cold-Atom Temporally Multiplexed Quantum Memory with Cavity-Enhanced Noise Suppression

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Communication

Background:

• Quantum repeaters are essential for long-distance quantum communication.
• Multiplexed quantum memories are crucial for efficient quantum repeater architectures.
• Previous architectures faced challenges with noise and mode distinguishability.

Purpose of the Study:

• To demonstrate a temporally multiplexed quantum repeater node.
• To enable efficient distribution of quantum information over large distances.
• To overcome limitations in current quantum memory technologies.

Main Methods:

• Utilized a laser-cooled cloud of Rubidium-87 (87Rb) atoms.
• Employed the Duan-Lukin-Cirac-Zoller protocol for creating photon-spin wave pairs.
• Controlled spin wave distinguishability using a magnetic field gradient for dephasing and rephasing.
• Embedded the atomic ensemble in a low finesse optical cavity to suppress noise.
• Implemented feed-forward readout for distinguishable retrieval of temporal modes.

Main Results:

• Demonstrated distinguishable retrieval of up to 10 temporal modes.
• Proved nonclassical correlations between photon pairs for each retrieved mode.
• Observed enhanced rates of correlated photon pairs with increased temporal modes.
• Showcased noise suppression in multimode operation via optical cavity embedding.

Conclusions:

• The demonstrated temporally multiplexed quantum repeater node is a key element for future quantum networks.
• This work advances the development of scalable quantum repeater architectures.
• The ability to handle multiple temporal modes significantly improves the efficiency of quantum repeaters.