Quantum internet breakthrough after 'quantum data' transmitted through standard fiber optic cable for 1st time

A new quantum computing study claims that a recent finding in the production, storage and retrieval of "quantum data" has brought us one step closer to the quantum internet.

Currently, quantum information is unstable over long distances and quantum bits, or qubits — the carriers of quantum information — are easily lost or fragmented during transmission.

Classical computer bits are transmitted today as pulses of light through fiber optic cables using devices called "repeaters" to amplify signals across the length of the network. To transmit qubits over longer distances the way classical computer bits are transmitted today we need similar devices that can store and retransmit quantum states across the whole network, ensuring signal fidelity no matter how far the data has to go.

These quantum memory devices could receive, store and retransmit qubit states. The new study, conducted at Imperial College London, the University of Southampton, and the Universities of Stuttgart and Wurzburg in Germany, claims to have achieved this using standard fiber optic cables for the first time. The findings were published April 12 in the journal Scientific Advances.

All in the photon source

The researchers stored and retrieved photons — one of the potential carriers of quantum information — using a new and potentially much more efficient method.

"There are two main types of single photon sources,a process called non-linear optical frequency conversion and those based on single emitters," Sarah Thomas, professor of physics at Imperial College, London, told Live Science. "It's been demonstrated many times before that we can store photons from nonlinear optics in a quantum memory because you can engineer the source and memory to match. We used a particular single emitter called a quantum dot, which is a nanocrystal of semiconductors."

Thomas said that using nonlinear optics is less reliable — a pair of usable photons isn't produced every time, whereas a single emitter quantum dot produces them at a higher rate.