The internet relies on cables, servers, and encryption systems that remain vulnerable to attacks. For years, researchers have explored quantum physics as a possible foundation for a more secure alternative. An experiment using standard fiber optics has overcome a major hurdle, bringing quantum technology closer to real-world networks.
A new milestone has been reached in the development of the so-called quantum internet. Scientists have successfully transmitted entangled light particles over a distance of 61 kilometers using ordinary optical fiber.
The breakthrough was achieved by a research team led by Thomas Gerrits of the U.S. National Institute of Standards and Technology (NIST) and was reported in the Journal of Optical Communications and Networking.
Quantum Entanglement at the Heart of the Experiment
At the center of the experiment is quantum entanglement.This occurs when two particles become linked through shared quantum properties, causing their measurements to remain closely correlated. Research into quantum entanglement played a key role in the work recognized by the 2022 Nobel Prize in Physics.
This property could be used to develop new communication methods and cryptographic key distribution systems that can detect attempts to intercept data.
The main challenge, however, is keeping these delicate quantum states intact as they travel over long distances. The problem becomes even more complicated when researchers try to use the telecommunications infrastructure already installed across cities.
Using standard optical fiber is particularly important because a future quantum internet would be impractical if it required entirely new networks to be built from scratch. Cities already contain vast fiber-optic infrastructures, making it possible to gradually incorporate quantum technologies into existing communication systems.
In reality, though, the process is far from straightforward.
Environmental Disturbances Threaten Quantum Signals
Entangled photon pairs are highly sensitive to their surroundings. Temperature fluctuations, vibrations, cable movement, and other physical disturbances can change the properties of the fiber and reduce the quality of the quantum signal.
As a result, a system that performs reliably under controlled laboratory conditions may encounter much greater challenges when operating on a real-world telecommunications network.
The American researchers addressed this challenge by introducing one of the experiment’s key components.
The team created an active stabilization system that continuously tracks changes in the fiber through reference signals. Whenever distortions occur, the system automatically applies real-time corrections, maintaining the conditions required for reliable quantum transmission.
The researchers then tested the system under real-world conditions rather than in a controlled laboratory environment.
Researchers tested the system using an existing 61-kilometer connection linking a NIST facility with the University of Maryland.
The network includes aerial sections in which the fiber runs along poles and other exposed structures. As a result, it faces far more environmental fluctuations and external interference than a fiber-optic cable operating under the controlled conditions of a laboratory.
The system was continuously tested for 24 hours.
The results were particularly encouraging. During 92.8% of the test period, the network maintained optimal operating conditions, while automatic calibration accounted for just 7.2% of the total time.
The Challenge of Maintaining Continuous Quantum Transmission
Maintaining stable transmission for such an extended period is important because practical communication networks must function continuously. A system that depended on frequent manual adjustments or highly controlled environments would be difficult to deploy on a large scale.
With automatic stabilization, however, that possibility becomes much more realistic.
The concept of a quantum internet is often linked to highly secure communications, but its potential extends well beyond cybersecurity.
Quantum networks could connect quantum computers in different locations, support new forms of distributed computing, and enable highly sensitive and precise sensing technologies.
Security remains one of the most compelling applications, however.
Quantum Mechanics Enables Ultra-Secure Key Distribution
Quantum mechanics makes it possible to design communication protocols in which attempts to observe certain quantum states can produce detectable changes. This could enable quantum cryptographic key distribution with security properties that cannot be achieved through classical systems alone.
Despite these advances, significant obstacles remain before a global quantum internet can become feasible. Researchers must extend transmission distances, improve reliability, develop quantum repeaters, and connect different quantum networks.
The 61-kilometer test does not overcome all of these challenges.
However, it demonstrates a crucial point: highly fragile quantum effects can be preserved while traveling through optical fibers similar to those already deployed across modern cities.
If this technology continues to develop, the same infrastructure that today carries videos, messages, and web traffic could eventually transmit an entirely new form of information.
Read the original article on: gizmodo
Read more:Your Teeth Might Reveal a Hidden Sign of Pancreatic Cancer Survival
