Materials scientists studying the efficiency of photons as an information carrier have developed a model that explains how this efficiency changes at higher wavelengths. Their findings could have major implications for a highly anticipated technological breakthrough: the development of quantum communication networks.
Today’s optical fibers can transmit photons (individual particles of light) at the wavelengths used for communication with minimal loss. In quantum systems, photons act like bits in a classical computer.
What does light have to do with the Internet?
The quantum internet doesn’t exist yet, but it’s expected to resemble a network of quantum computers that transmit information as quantum bits, or qubits. These qubits are particles in a quantum state that can contain much more information than just a value of 0 or 1 like bits in a classical computer.
As Gizmodo previously reported, the quantum internet wouldn’t function all that differently from the internet we currently access through our browsers, but the envisioned technology would be able to encrypt information far more securely than the information on the internet today, and it would use the laws of quantum mechanics to achieve its goal.
What did the researchers find?
In their new paper, published last month, APL PhotonicsPhysicists have presented a model outlining the role of electron-photon coupling in certain single-photon emitters. Their work suggests ways to improve the efficiency of these photon emitters.
“Atoms are constantly vibrating, and those vibrations can take energy away from the light emitter,” UC Santa Barbara materials scientist and study co-author Chris Van de Walle said in the university’s release. “As a result, rather than defects emitting photons, the atoms can vibrate, reducing the efficiency of light emission.”
The team says that a “Goldilocks” single-photon emitter has yet to be found, but they believe that the transmitted energy would be around 1.5 electron volts.
“Given the much higher efficiencies achievable at shorter wavelengths, we propose that quantum frequency conversion should be considered in parallel with direct generation if telecommunication wavelengths are required for transmission over optical fibers,” the team writes.
“Careful selection of host materials and atomic-level engineering of vibrational properties are two promising ways to overcome low efficiency,” Mark Turiansky, a researcher at the University of California, Santa Barbara, and principal investigator on the project, said in the same release.
Another way to address the efficiency loss, the team said, is to couple it to a photonic cavity, a tool that can be used to “open up frequency bands where the propagation of electromagnetic waves is forbidden, regardless of their direction of propagation in space,” as another team of researchers put it at IEEE.
While we’re still a long way from a quantum internet, the groundwork for it has been in the works for the past decade. In early 2020, the Department of Energy released a blueprint for “Building a Nationwide Quantum Internet.” In addition to enabling secure quantum communications, the plan would also enable quantum computing to scale and support existing sensor networks.
Don’t hold your breath waiting for the quantum future — you’ll turn blue — but know that today’s fundamental research in materials and computer science is laying the groundwork for entirely new kinds of communication.
