Quantum internet moves from dedicated labs toward existing fiber

Overview

For years, quantum networks needed their own private fiber, sealed off from ordinary internet traffic. Northwestern University just broke that rule. Its team sent entangled photons through 24.4 kilometers of Chicago telecom cable while that same cable carried normal commercial internet data.

The quantum link held together with more than 94% fidelity. That matters because it suggests a future quantum internet could ride on the fiber already buried under cities, instead of requiring a costly new network built from scratch.

Why it matters

If quantum links can share fiber that is already in the ground, a hack-resistant quantum internet gets cheaper and years closer.

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Key Indicators

24.4 km

Fiber length

Distance the entangled photons traveled through a working metropolitan cable.

>94%

Entanglement fidelity

How well the quantum link survived alongside heavy classical data traffic.

Optical bands shared

Quantum signals ran in the O-band while normal traffic used the C-band on one fiber.

$1.2B

US quantum program funding

Authorized by the 2018 National Quantum Initiative Act that backs this line of work.

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People Involved

Prem Kumar

Senior author of the study; leads follow-on teleportation work

Gina Talcott

First author of the Optica Quantum paper

Organizations Involved

Northwestern University

Research University

Ran the demonstration

Chicago-area university whose engineering lab showed quantum entanglement can share fiber with live internet traffic.

US Department of Energy quantum internet program

Federal Program

Sets national roadmap this work advances

Federal effort, launched with a 2020 blueprint, to build a national quantum network across cities and states.

Timeline

December 2018 July 2026

5 events Latest: July 23rd, 2026 · 3 weeks ago

Tap a bar to jump to that date

July 2026
Entanglement distributed over live commercial fiber
Latest Milestone

Northwestern distributes entanglement between remote nodes over 24.4 km of metropolitan fiber carrying commercial traffic, holding above 94% fidelity. Published in Optica Quantum.
July 23rd, 2026
December 2024
Teleportation over busy fiber demonstrated
Milestone

Kumar's team performs the first quantum teleportation over a fiber that also carries live internet traffic, a precursor to the entanglement result.
December 20th, 2024
July 2020
DOE releases quantum internet blueprint
Policy

The Department of Energy lays out a national roadmap, including a milestone to run quantum protocols over existing fiber networks.
July 23rd, 2020
February 2020
Chicago 52-mile quantum loop goes live
Milestone

Argonne and the University of Chicago entangle photons across a dedicated 52-mile fiber loop, one of the longest land-based quantum links in the US at the time.
February 19th, 2020
December 2018
National Quantum Initiative signed into law
Policy

The US authorizes about $1.2 billion for quantum research, including quantum networking, setting the funding base for later work.
December 21st, 2018

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

June 2017

China's Micius satellite entangles photons over 1,200 km (2017)

China's Micius satellite distributed entangled photon pairs between two ground stations more than 1,200 kilometers apart. It set a distance record for entanglement and proved space-based quantum links could work.

Then

The result was hailed as a landmark and led to a quantum-secured video call between Beijing and Vienna in 2017.

Now

It established satellites as one path to long-range quantum communication, but one requiring expensive dedicated hardware in orbit.

Why this matters now

Micius solved distance with new infrastructure in space. Northwestern is taking the opposite bet: reuse the fiber already on the ground.

February–July 2020

Chicago 52-mile quantum loop and DOE blueprint (2020)

Argonne National Laboratory and the University of Chicago entangled photons across a 52-mile dedicated fiber loop. Months later, the Department of Energy unveiled a national quantum internet blueprint at the University of Chicago.

Then

The loop became a testbed for US quantum networking research and expanded toward a three-node link with Fermilab.

Now

It set national milestones, including running quantum protocols over existing fiber, that later work would try to hit.

Why this matters now

That loop used fiber reserved for quantum use. The 2026 result checks off the blueprint's harder goal: sharing fiber with live commercial traffic.

Mid-to-late 1990s

Wavelength-division multiplexing scales the internet (1990s)

Telecom firms began sending many separate data channels down a single fiber at different wavelengths, a technique called wavelength-division multiplexing. It multiplied the capacity of cable already in the ground.

Then

Carriers avoided digging vast amounts of new cable during the internet boom, cutting costs sharply.

Now

Sharing one fiber among many signals became the economic backbone of the modern internet.

Why this matters now

Northwestern's band-separation trick is the same idea applied to quantum: fit a new kind of signal onto existing fiber instead of building fresh lines.