A groundbreaking achievement in quantum communications has been demonstrated by engineers at Northwestern University, who successfully performed quantum teleportation through fiber optic cables actively carrying internet traffic - a feat previously thought impossible.
"Nobody thought it would be possible to achieve this," said Professor Prem Kumar, who led the pioneering study published in Optica. "Our work shows a path towards next-generation quantum and classical networks sharing a unified fiber optic infrastructure."
The team transmitted quantum information over a 30-kilometer (18.6 mile) fiber optic cable while regular internet data flowed through it simultaneously. This breakthrough suggests existing telecommunications infrastructure could potentially support both classical and quantum communications.
Quantum teleportation leverages quantum entanglement to instantly transfer information between particles, without physically sending the particles themselves. "By performing a destructive measurement on two photons – one carrying a quantum state and one entangled with another photon – the quantum state is transferred onto the remaining photon, which can be very far away," explained Jordan Thomas, lead author of the study.
Many experts were skeptical about achieving quantum teleportation alongside classical communications, believing the delicate quantum signals would be disrupted by the massive amount of light particles from regular internet traffic. However, Kumar's team overcame this by identifying specific wavelengths with minimal interference and implementing specialized filtering systems.
The successful demonstration opens new possibilities for quantum networks to leverage existing fiber optic infrastructure rather than requiring dedicated new systems. "If we choose the wavelengths properly, we won't have to build new infrastructure. Classical communications and quantum communications can coexist," noted Kumar.
The researchers are now planning experiments over longer distances and real-world underground cables. They aim to demonstrate entanglement swapping using multiple pairs of entangled photons - another key step toward practical quantum networking applications.
This achievement represents a major advance toward integrating quantum capabilities into current telecommunications systems, potentially enabling ultra-secure communications across existing fiber optic networks.