1st-ever quantum, classical internet merger achieved via single optical fiber

Researchers have developed a new way to unify quantum and traditional internet.

The Leibniz University Hannover researchers have designed a novel “transmitter and receiver” approach for sending entangled photons across optical fibers.

This quantum internet carries information using light particles known as photons, which are bound together in an unusual quantum state known as entanglement. Interestingly, this technique promises impenetrable security in computers.

“To make the quantum Internet a reality, we need to transmit entangled photons via fiber optic networks,” said Michael Kues, Head of the Institute of Photonics and Board Member of the PhoenixD Cluster of Excellence at Leibniz University Hannover.

“We also want to continue using optical fibers for conventional data transmission. Our research is an important step to combine the conventional Internet with the quantum Internet,” Kues added.

Same color channel

The digital age is transforming the world at an unprecedented pace. Threats, however, evolve in tandem with technological advancement.

Future quantum computers — although promising enormous processing capability — have the potential to break encryption systems. This is where the quantum internet comes in.

However, integrating it with the existing internet infrastructure has been a major challenge.

In this new study, the researchers have created a mechanism for sending both entangled photons and regular laser light over the same optical wire.

Interestingly, the experiment showed that laser pulses don’t disrupt the entanglement of photons.

This was achieved through manipulating laser light. They were able to rapidly modify the color (or frequency) of a laser pulse using an electrical signal. This is crucial to match the color of the laser pulse to the color of the entangled photons. Once the colors match, both forms of light may pass via the same optical cable without interfering with one another.

“We can change the color of a laser pulse with a high-speed electrical signal so that it matches the color of the entangled photons. This effect enables us to combine laser pulses and entangled photons of the same color in an optical fiber and separate them again,” explained Philip Rübeling, a doctoral student at the Institute of Photonics.

Interestingly, this is the “first time” researchers have demonstrated that photons may be conveyed in the same color channel as laser light.

Advancing telecommunications

This is a significant advance because it allows both traditional internet data (delivered by laser pulses) and quantum information (carried by entangled photons) to share the same fiber optic cable.

“The entangled photons block a data channel in the optical fiber, preventing its use for conventional data transmission,” added Jan Heine, a doctoral student in Kues’ group.

Previously, entangled photons consumed an optical fiber’s full bandwidth, making regular data transfer impossible. This novel approach enables both to coexist while boosting the fiber’s capacity.

This novel experiment has the potential to advance telecommunications by enabling the quantum internet to be integrated into the current fiber optic infrastructure.

“Our experiment shows how the practical implementation of hybrid networks can succeed,” added Kues in the press release.

The findings were published in the journal Science Advances.