3 months ago
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Materials scientists exploring the efficiency of photons as carriers of information have developed a model that explains how the efficacy of those light particles changes at higher wavelengths. Their findings could significantly impact the development of a highly anticipated technological breakthrough: a quantum communications network.
Today’s fiber-optics are capable of transmitting photons (individual light particles) with minimal loss at the wavelengths used for telecommunications. In a quantum system, photons function like bits in a classical computer.
What does light have to do with the internet?
The quantum internet does not yet exist, but it is expected to resemble a network of quantum computers transmitting information as quantum bits, or qubits. These qubits are particles that are in quantum states, allowing them to contain more information than just a value of 0 or 1, as classical computer bits do.
As previously reported by Gizmodo, the quantum internet won’t function much differently than the internet you’re accessing through your current browser. But the putative technology should allow information to be encrypted with much more security than information on the internet today, and will use the rules of quantum mechanics to accomplish that goal.
What did the researchers find?
In their new paper—published last month in APL Photonics—the physicists present a model that outlines the role of electron-photon coupling in a type of single-photon emitter. Their work suggests ways to improve the efficiency of these photon emitters.
“Atoms are constantly vibrating, and those vibrations can drain energy from a light emitter,” said Chris Van de Walle, a materials scientist at UC Santa Barbara and co-author of the paper, in a university release. “As a result, rather than emitting a photon, a defect might instead cause the atoms to vibrate, reducing the light-emission efficiency.”
The team noted that they don’t believe a “Goldilocks” single-photon emitter has yet been discovered, but they believe it would have a transmission energy of around 1.5 electronvolts.
“In light of the much higher efficiencies achievable at shorter wavelengths, we suggest that if telecom wavelengths are required for transmission in optical fibers, quantum frequency conversion should be considered alongside direct generation,” the team wrote.
Concept art of a quantum defect emitting a photon. © Illustration: Mark Turiansky “Choosing the host material carefully, and conducting atomic-level engineering of the vibrational properties are two promising ways to overcome low efficiency,” said Mark Turiansky, a researcher at UC Santa Barbara and lead researcher of the project, in the same release.
Another method to deal with lower efficiency, the team wrote, is coupling to a photonic cavity, a tool that can be used to “open up frequency bands within which the propagation of electromagnetic waves is forbidden irrespective of the propagation direction in space,” as another team put it in IEEE.
We’re a long ways off from a quantum internet, but the groundwork for it has been a project of the last decade. In early 2020, the Department of Energy released its blueprint for “Building a Nationwide Quantum Internet,” which, besides secure quantum communiques, could upscale quantum computing and help existing sensor networks.
Don’t hold your breath awaiting the quantum future—you’ll turn blue—but know that the fundamental research in materials and computer science today is laying the foundation for a whole new kind of communication.
