A Quantum Solution to The Fermi Paradox? Study Suggests Aliens Could Use Interstellar Quantum Communication Technology to Hide Chats

Insider Brief

• The Fermi paradox suggests that the vastness of universe should contain many civilizations that are able to communicate, but that there’s little evidence of these signals.
• Current search for extraterrestrial intelligence (SETI) efforts have focused on detecting radio waves or laser signals sent across interstellar distances.
• A researcher suggests that the next leap in SETI may lie in exploring quantum communications for hints of conversations among aliens.

It’s been a topic of discussion — and derision — ever since Enrico Fermi brought up the subject during a lunch break discussion at the Los Alamos National Laboratory in 1950: if the skies are so full, why is it so quiet.

In other words, this Fermi paradox suggests that the vastness of universe should contain many, many civilizations that are able to communicate, but that there’s little evidence of those signals. This debate has, at least partially, spurred the search for extraterrestrial intelligence (SETI), which has traditionally focused on detecting radio waves or laser signals sent across interstellar distances — and therefore guided by the principles of classical communication.

However, a recent study by a Canadian researcher suggests that the next leap in SETI may lie in the realm of quantum communication. This new take on that longstanding puzzle might not just explain the enigmatic Fermi paradox and give a boost to quantum communication research, but — who knows? –even get us on the same wavelength of our extraterrestrial neighbors.

Quantum Communication Background

Quantum communication is a field that explores the transmission of information using quantum bits or qubits. Unlike classical bits, which can be either 0 or 1, qubits can exist in superpositions of both states simultaneously. This unique property allows quantum communication to perform certain tasks that classical communication cannot, such as quantum cryptography, teleportation, and superdense coding.

In a study published in ArXiv, Latham Boyle from the Higgs Centre for Theoretical Physics, University of Edinburgh, UK, and the Perimeter Institute for Theoretical Physics on ArXiv, investigates the feasibility of interstellar quantum communication and its implications for SETI.

Boyle argues that “photon qubits can retain their quantum coherence over interstellar (and even intergalactic) distances, raising the prospect of interstellar quantum communication.”

This concept suggests that civilizations could communicate using quantum signals — rather than classical signals — that would be imperceptible with current SETI methods.

The Challenge of Quantum Capacity

One of the reasons that science is so fun is it gives you a chance to disabuse people of the notion that things can be easy or simple. Boyle does this in his assessment on the possibility of quantum communication across vast, interstellar spaces.

To assess the potential for quantum communication across interstellar distances, the study analyzes the quantum capacity of an interstellar channel. Quantum capacity is the maximum rate at which qubits can be reliably transmitted over a communication channel. For quantum communication to be possible, this capacity must be greater than zero, according to the researcher.

Boyle outlines specific criteria that must be met for interstellar quantum communication to occur:

Wavelength Constraints: The photon wavelengths must be less than 26.5 cm to avoid interference by the cosmic microwave background.

As Boyle explains, “using constraints on quantum depolarizing channels and properties of the diffuse astrophysical background radiation, we show that to successfully transmit quantum information, the exchanged photons need to have certain properties.”

Telescope Size: The telescopes involved in the communication must have an effective diameter much larger than those we currently possess. Boyle points out that for effective communication between Earth and Proxima Centauri, the nearest star to our solar system, that the telescopes would need to be over 100 kilometers in diameter. For sake of comparison, the diameter of Greater London is roughly 50 kilometers, so a 100-kilometer circle would be about twice the size of London. The largest telescopes today are only about 40 meters across.

These constraints underscore the technological challenges of implementing interstellar quantum communication. Anyone stuck day after day in traffic during simple road work probably realizes the construction of a 100-kilometer telescope is a bit beyond our capabilities, but the study suggests that such advancements could one day be possible.

A New Perspective on the Fermi Paradox

Despite the impediments to interstellar communication, Boyle suggests that if advanced civilizations can overcome those hurdles and are using quantum communication, their signals would be undetectable with the current technology that is scouring the skies for ET.

Boyle explains that “the signal must be so highly directed that only the intended receiving telescope can hope to detect any sign of the communication.”

This contrasts with classical communication, where signals are often broadcast indiscriminately. As a result, civilizations communicating via quantum channels might be sending signals that are effectively invisible to us.

Additionally, the study points out that civilizations capable of quantum communication would likely have the means to determine whether we possess the necessary technology to receive their signals.

“If the sender has a large enough telescope to communicate quantumly with us, they necessarily also have enough angular resolution to see that we do not yet have a sufficiently large receiving telescope,” Boyle writes.

Future Directions and Possibilities

While this concept of interstellar quantum communication is still theoretical, the study opens up new possibilities for the future of SETI. The potential advantages of quantum communication, such as increased security and speed, make it an attractive area of research for both physicists and astronomers.

One intriguing application mentioned in the study is Astronomically Long Baseline Interferometry (ALBI). This technique would use quantum communication to link telescopes across astronomical distances, creating an “effective angular resolution” that could vastly improve our ability to observe distant objects in the universe.

The study also suggests that quantum repeaters, devices that extend the range of quantum communication, could play a crucial role in establishing interstellar channels. By placing these repeaters at strategic points along a communication path, the need for massive telescopes could be reduced, making quantum communication more feasible.

While the urge to make “ET Quantum Phone Home” jokes is irresistible, the study’s exploration of interstellar quantum communication actually offers a thought-provoking challenge and, by expanding our understanding of communication beyond classical paradigms, the ideas in the study could help researchers unlock new avenues for detecting extraterrestrial intelligence and resolving the Fermi paradox.

While the technological hurdles are significant, the potential rewards are equally substantial. As Boyle concludes, “our galaxy and universe do permit interstellar quantum communication, but the above constraints impose a stringent technological threshold we have not yet reached.”

While we may not be sharing memes with our alien friends over interstellar quantum IM anytime soon, the work could serve as inspiration to make terrestrial improvements to the quantum communication research agenda.

For example, proposed constraints to facilitate quantum communication over vast interstellar distances may be daunting, but the probing of that challenge could help push researchers to explore the boundaries of telescope technology, unlocking new methods for secure communication, data transfer and computing, leveraging the properties of quantum mechanics.