For the quantum internet aliens can communicate!

between them Astrophysicist from the University of Edinburgh, Arjun Berera and Jaime Calderon-Figueroa, recently published in the famous magazine Physical examination d An article that will undoubtedly attract the attention of the founding members of the ideas behind the program, for example Carl Sagan. The publication is available for free here arXiv And it raises the question of whether a technologically advanced civilization could not use a technology from quantum information theory, such as teleportation in a quantum state, to communicate with its other members. blue chain Seti—according to the former French president’s job title, Albert Ducros.

The question is raised whether the quantum computing revolution will lead to some of the dreams of its pioneers, a technologically advanced civilization could only use. Quantum computer Interacting precisely with each other accounts for the EPR effect behind the concept of quantum teleportation. We doubt we can pass much more information through Quantum teleportation is only with waves Radio In the classical world, moreover, we want to develop a kind ofInternet Quantum using beams Laser.

Quantum teleportation for dummies

Let’s have a few reminders about quantum teleportation that Futura already explained on this topic.

When it all started in 1993 Physicist Charles Bennett and his colleagues (including Gilles Brassard and Claude Crepeau) are working here IBM published an article in which they proposed a protocol Experimental to allow teleportation of quantum states. Austrian after four years Anton Zellinger published the nature An article announced that, along with other researchers, he was able to implement Bennett’s ideas for quantum teleportation.

The performance and especially the name of the event certainly immediately evokes the enthusiasm of fans of the series. Star Trek, there hopes to make one of science fiction’s biggest dreams come true. Unfortunately, with this quantum phenomenon it is unlikely that one day the equivalent of Mr. Spock and Captain Kirk will disappear from the face of the earth. pandora or a Super Earth To teleport inside the Enterprise.

The reason is that in experiments performed by physicists, only a quantum state is teleported, so information, not matter. Furthermore, the system the physical Primary bearing data is destroyed. In the best case, a clone Complete, includes memory and state of consciousness, letter one Star Trek Eventually the Enterprise could be rebuilt, but the original would be well and truly dead.

Quantum teleportation itself depends on its occurrenceQuantum entanglement Theoretically discovered by Einstein And Schrodinger In the 1930s. This event is in the hearts of the famous The ERP Paradox and whose existence was verified in 1982 Align aspect and his colleagues.

Produced for capsule display What happened to the invention of the past?, broadcast on Canal Savoir. This citation traces the evolution of an invention selected among the 10 Inventions of 1993 by Gilles Brassard (University of Montreal) and Claude Crepeau (McGill University). Quebec Science : Quantum teleportation. © Quebec Research Fund

When two particles are quantum entangled, certain physical quantities are assigned to one of the two particles when they are measured in the other. The effect seems to be instantaneous and if on Earth Alice measures in thousands of the particles stuck to Bob.light yearsBob will receive measurement results on his own particles that depend on Alice’s, as if a signal had traveled much faster than light from Alice to Bob. From the tests carried out, but which do not prove that the effect is really immediate.

However, although transluminal correlation exists between two particles, it is impossible to build a phone that can communicate faster than light in this way.

We can still use a quantum state carrying lots of information that will be transferred to Alice’s particle, by performing certain measurements, Alice will then teleport the quantum state and all the information to Bob’s particle.

But without knowing what the results of Alice’s own measurements were, Bob could not extract the information encoded in his particle under certain measurements.

For example, if Alice uses multiple pairs of laser photons to transmit a quantum state, she must send the results of her measurements to Bob by radio wave. So we cannot communicate faster than light between stars, even if we suspect that the amount of information transferable by working with a quantum computer connected by quantum teleportation would be much greater.

Now let’s have a few reminders about the program and its history.

Seti on the tail of the laser

The motivation for Carl SaganWhen he helped develop the program Search for Extra-Terrestrial Intelligence, We tried to find out if XX had a chance to survivee and XXIe Century Concretely Seti’s primary purpose was to detect signals from extraterrestrial civilizations with a radio telescope and if possible determine if these signals contained a message for our destination… and respond to them.

In the last century the Cold War was in full swing and the proliferation of nuclear weapons was not well seen. today the spectrum Nuclear war has moved away. However, its consequences global warming And the scarcity of natural resources, which, with our overpopulated and irrational world, has not entirely ruled it out. The discovery of one or more ET civilizations can give us confidence in a future that seems very dark, if we believe the famous Meadows Forecast Report.

However, the best way to detect and communicate with technologically advanced ET civilizations may not be through the use of radio telescopes. The way would be in the form of projects designed to try to detect emissions from ET civilizationsLaser pulsesWhether they are by-products of propulsion techniques solar sail Interstellar, like the project Breakthrough Starshot, or actual attempts at interstellar communication. The idea that extraterrestrials might prefer to communicate interplanetary, or even interstellar distances, using lasers is outdated. It has already been formulated Schwartz and Towns In 1961, one year after Townes invented the laser, and two years after Coconi and Morrison It proposed the basic concept of the program.

Some pictures of laserset. To get a fairly accurate French translation, click on the white rectangle at the bottom right. English subtitles will then appear. Then click on the nut to the right of the rectangle, then “Subtitle” and finally “Auto Translate”. Select “French”. © That is the institute

We are now almost ready to understand the work of Arjun Berera and Jaime Calderón-Figueroa.

We have already done quantum teleportation between the ground and a satellite in space, the Chinese have achieved remarkable performance in this regard in recent years.. Initially, they use a Laser Diode whose photons were trapped with a nonlinear optics device and sent into space to test the idea of ​​a future planetary quantum internet.

One advantage of sending photons into space is that they travel fasterthe atmosphere Earthly to enter the void of space. However, it appears that, as in the case of computers, the problem of decoherence must be solved by the quantum internet. Indeed, the quantum state carried by photons is fragile and can be decayed by the medium they pass through, limiting the range of information transfer.

The two astrophysicists therefore asked themselves how many intercepted photons were sent from Earth, say Exoplanets around Proxima Centauri, could reliably teleport information. More generally, what would be the probability at greater interstellar distances the milky way.

They are thus taken into accountExploitation light by gas and disturbances from dust, plasma particles and cosmic raysto its effect gravity They are photons Cosmic radiation or the sun.

Remarkably, there will be no real problem and works with photons in this case x-ray We can reach distances of millions of light years, so directly a quantum internet that could be intergalactic.

Specifically, to demonstrate the existence of transfer of information via quantum teleportation of ET sources, it is necessary to simultaneously find a double signal, for example a visible laser beam as one wishes to detect its members. lasersetCoupled with a radio signal that would provide a means of deciphering the quantum state transferred by laser photons.

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