In the field of searching for extraterrestrial intelligence (SETI), studies have historically relied on classical methods such as radiotelescopes, optical telescopes, and analysis of light signals from exoplanets. However, new scientific approaches based on quantum mechanics are being explored as potentially more effective for interstellar communication and addressing the Fermi paradox – the mystery of the absence of evidence for extraterrestrial civilizations.
Latam Boyle, a researcher at the Center for Theoretical Physics at the University of Edinburgh, has proposed the use of quantum communications for interstellar communication. He suggests that specific frequency ranges in our galaxy, surrounded by relict radiation, could be suitable for quantum communications. However, implementing such communication systems would require telescopes significantly larger than those currently in use.
Boyle highlights the concept of qubits as a crucial element in this system. Qubits are units of quantum information that can exist in multiple states simultaneously due to quantum superposition. Unlike classical bits, which are either a “0” or a “1”, qubits can be in both states concurrently, making quantum information transmission much more powerful than traditional methods.
Recent experiments have demonstrated that quantum entanglement can be preserved over vast distances, even reaching interstellar scales. Successful trials have involved entangled photons separated by over a thousand kilometers, with one on Earth and the other in orbit. These findings showcase the potential for maintaining quantum communication over galactic distances, opening up new possibilities for interstellar communication.
In his research, Boyle focused on the physical requirements for sending and receiving such quantum signals. The “quantum capacity” of the channel, which dictates the maximum speed of quantum information transmission, is a key parameter. Successful transmission necessitates specific frequency ranges and the use of very large telescopes whose dimensions are determined by the wavelength of the transmitted photons and the distance between sender and receiver.
An important outcome of Boyle’s study is the determination that photons must have a wavelength of less than 26.5 cm for effective transmission, to avoid interference from relict radiation. However, to transmit a signal to a distance such as the nearest proximity of Proxima Centauri (4.25 light years from Earth), an Earth-based telescope would need a diameter of at least 100 kilometers. For reference, the largest telescope currently under construction, the European Extremely Large Telescope in Chile, will only have a diameter of 40 meters.