Bereits im Februar 2020 haben Wissenschaftler des Argonne National Laboratory des US-Energieministeriums und der University of Chicago herausgefunden , dass sie eine Quantenverschränkung erreicht haben, bei der das Verhalten eines Paares zweier winziger Teilchen miteinander verknüpft wird, so dass ihre Zustände identisch sind ein 83,7 Kilometer langes Quantenschleifennetz in den Vororten von Chicago.
Sie fragen sich vielleicht, worum es in der ganzen Aufregung geht, wenn Sie kein Wissenschaftler sind, der mit der Quantenmechanik vertraut ist - das heißt, das Verhalten von Materie und Energie auf der kleinsten Ebene der Realität, das sich besonders von der Welt unterscheidet, die wir sehen können uns.
But the researchers' feat could be an important step in the development of a new, vastly more powerful version of the internet in the next few decades. Instead of the bits that today's network uses, which can only express a value of either 0 or 1, the future quantum internet would utilize qubits of quantum information, which can take on an infinite number of values. (A quibit is the unit of information for a quantum computer; it's like a bit in an ordinary computer).
That would give the quantum internet way more bandwidth, which would make it possible to connect super-powerful quantum computers and other devices and run massive applications that simply aren't possible with the internet we have now.
"A quantum internet will be the platform of a quantum ecosystem, where computers, networks, and sensors exchange information in a fundamentally new manner where sensing, communication, and computing literally work together as one entity, " explains David Awschalom via email. He's a spintronics and quantum information professor in the Pritzker School of Molecular Engineering at the University of Chicago and a senior scientist at Argonne, who led the quantum-loop project.
Explaining the Quantum Internet
Warum brauchen wir das und was macht es? Für den Anfang ist das Quanten-Internet kein Ersatz für das reguläre Internet, das wir jetzt haben. Es wäre eher eine Ergänzung oder ein Zweig davon. Es wäre in der Lage, einige der Probleme zu lösen, die das aktuelle Internet plagen. Zum Beispiel würde ein Quanten-Internet einen viel größeren Schutz vor Hackern und Cyberkriminellen bieten . Wenn Alice in New York über das Internet eine Nachricht an Bob in Kalifornien sendet, verläuft diese Nachricht derzeit mehr oder weniger geradlinig von einer Küste zur anderen. Unterwegs verschlechtern sich die Signale, die die Nachricht senden. Repeater lesen die Signale, verstärken und korrigieren die Fehler. Dieser Prozess ermöglicht es Hackern jedoch, "einzubrechen" und die Nachricht abzufangen.
However, a quantum message wouldn't have that problem. Quantum networks use particles of light photons to send messages which are not vulnerable to cyberattacks. Instead of encrypting a message using mathematical complexity, says Ray Newell, a researcher at Los Alamos National Laboratory, we would rely upon the peculiar rules of quantum physics. With quantum information, "you can't copy it or cut it in half, and you can't even look at it without changing it." In fact, just trying to intercept a message destroys the message, as Wired magazine noted. That would enable encryption that would be vastly more secure than anything available today.
"The easiest way to understand the concept of the quantum internet is through the concept of quantum teleportation," Sumeet Khatri, a researcher at Louisiana State University in Baton Rouge, says in an email. He and colleagues have written a paper about the feasibility of a space-based quantum internet, in which satellites would continually broadcast entangled photons down to Earth's surface, as this Technology Review article describes.
"Quantum teleportation is unlike what a non-scientist's mind might conjure up in terms of what they see in sci-fi movies, " Khatri says. "In quantum teleportation, two people who want to communicate share a pair of quantum particles that are entangled. Then, through a sequence of operations, the sender can send any quantum information to the receiver (although it can't be done faster than light speed, a common misconception). This collection of shared entanglement between pairs of people all over the world essentially constitutes the quantum internet. The central research question is how best to distribute these entangled pairs to people distributed all over the world. "
Once it's possible to do that on a large scale, the quantum internet would be so astonishingly fast that far-flung clocks could be synchronized about a thousand times more precisely than the best atomic clocks available today, as Cosmos magazine details. That would make GPS navigation vastly more precise than it is today, and map Earth's gravitational field in such detail that scientists could spot the ripple of gravitational waves. It also could make it possible to teleport photons from distant visible-light telescopes all over Earth and link them into a giant virtual observatory.
"You could potentially see planets around other stars, " says Nicholas Peters, group leader of the Quantum Information Science Group at Oak Ridge National Laboratory.
Es wäre auch möglich, dass Netzwerke von superstarken Quantencomputern auf der ganzen Welt zusammenarbeiten und unglaublich komplexe Simulationen erstellen. Dies könnte es Forschern ermöglichen, beispielsweise das Verhalten von Molekülen und Proteinen besser zu verstehen und neue Medikamente zu entwickeln und zu testen.
Es könnte auch Physikern helfen, einige der langjährigen Rätsel der Realität zu lösen. "Wir haben kein vollständiges Bild davon, wie das Universum funktioniert", sagt Newell. "Wir haben ein sehr gutes Verständnis für die Funktionsweise der Quantenmechanik, aber kein sehr klares Bild der Auswirkungen. Das Bild ist verschwommen, wo sich die Quantenmechanik mit unserer gelebten Erfahrung überschneidet."
Herausforderungen beim Aufbau des Quanteninternets
But before any of that can happen, researchers have to figure out how to build a quantum internet, and given the weirdness of quantum mechanics, that's not going to be easy. "In the classical world you can encode information and save it and it doesn't decay, " Peters says. "In the quantum world, you encode information and it starts to decay almost immediately. "
Another problem is that because the amount of energy that corresponds to quantum information is really low, it's difficult to keep it from interacting with the outside world. Today, "in many cases, quantum systems only work at very low temperatures," Newell says. "Another alternative is to work in a vacuum and pump all the air out. "
In order to make a quantum internet function, Newell says, we'll need all sorts of hardware that hasn't been developed yet. So it's hard to say at this point exactly when a quantum internet would be up and running, though one Chinese scientist has envisioned that it could happen as soon as 2030.
Now That's Interesting
Albert Einstein, who questioned the validity of quantum mechanics, called quantum entanglement "spooky action at a distance," as Technology Review explains.
Originally Published: Mar 30, 2020
