Quantum communication advances through real-world fiber and high-capacity memory

Researchers have achieved significant milestones in quantum communication, demonstrating the ability to maintain entanglement across both specialized laboratory setups and real-world infrastructure.

In Maryland, scientists from the National Institute of Standards and Technology and the University of Maryland successfully transmitted entangled photons across 62 kilometers of existing fiber-optic cable. Much of this fiber is strung above ground, exposing it to environmental stressors like temperature changes and wind. To combat signal distortion, the team utilized a real-time correction system to stabilize the fragile quantum states, proving that quantum networking may be viable using current telecommunications infrastructure.

In a separate advancement, a team including researchers from the University of Geneva, alto University, and PSL University demonstrated the storage of entanglement across 16,340 temporal modes using a rare-earth-ion ensemble quantum memory. This represents a substantial increase over previous limits of approximately 8,000 modes. By utilizing a 250MHz bandwidth and storing photons for up to 63 microseconds over 5.66km of metropolitan fiber, the breakthrough allows for significantly higher data transmission rates by exploiting multiple spectral channels.