The first quantum simulation of a wormhole opens a new door to understanding the universe Sciences

Quantum mechanics and relativity theory are like Cain and Abel, two mismatched children of the same nature, but one focused on matter on subatomic scales and the other connected to the macroscopic world. Both theories are not identical, so finding a point of reconciliation is essential to understanding physical reality. A step in this direction has been taken with the first quantum simulation of a wormhole performed using the Google Sycamore processor, as published on Wednesday. nature. Through this experiment, it was observed, according to Maria Spiropoulou, a physicist at the California Institute of Technology (Caltech) and one of the authors of the work, “that the properties of a quantum system match what would be expected in a gravitational system.”, a discovery that allows progress in the study of black holes and the hypothesis Quantum gravity in the laboratory using computers based on these mechanics. A new way to understand the universe.

A wormhole, also known as the Einstein-Rosen Bridge, is a shortcut through space and time, as if there were a short path between two galaxies light years away. As shown in theory, this shortcut could be created when two entangled black holes are created. A wormhole would be similar to two tears associated with smaller mouths and black holes at the more open ends.

However, unlike what is reflected in science fiction films, this abbreviation in space cannot be used on its own to transmit information. The problem is that if anything or a message is thrown through it, it will never reach the other end, as the hole expands and narrows. In fact, the body ends up destroyed in a central singularity, as is typical when it enters a black hole, which does not even allow light to pass through. However, if a conventional interaction (traveling at the speed of light) is established between two observers located at the ends of the wormhole, the wormhole opens in a traversable way.

This phenomenon cannot be observed experimentally, because it is not possible to create two entangled black holes in the laboratory. However, it is possible to study the “holographic equivalent” of this process, which is one of the achievements of the study published today.

Alberto Casas, CSIC Research Professor at the Institute for Theoretical Physics (CSIC-UAM) and author of a book Quantum revolution (Versions B, 2022), simplifies it to make it understandable. “It’s like a cylindrical box. There are three dimensions inside, but the ends are two-dimensional and flat. Whatever happens inside, with gravity, has a reflection or can be seen on the eyelid, where there is no gravity.” It is the so-called holographic principle, which is suspected to be realized in a consistent quantum theory of gravity and in which, as Casas explains, “what happens in a theory of gravity has an equivalent in a theory without it and in one dimension less.” Specifically, the wormhole in the theory of gravity can Consider it an entangled quantum system in theory without it.Transportation of information through a wormhole would be seen as a similar phenomenon to quantum teleportation in theory without gravity.

This is the work published on Wednesday. The authors have created an entangled system between two parts of a quantum computer, the three-dimensional equivalent of a wormhole. And they verified that there is a transmission of information between those parts through this kind of quantum teleportation, simulating exactly what would happen through a parabolic wormhole,” Casas explains.

This phenomenon is very striking, since the letter written by Alice [nombre utilizado en física cuántica para definir a un emisor] It appears to have been irretrievably lost within the first subsystem, but soon reappears entirely in the Bob subsystem [el receptor del mensaje]. As if Alice wrote a message on the surface of the water. Apparently, it will get lost in the movements of trillions of water molecules, making it impossible to retrieve it. However, we can imagine that after a while, the entire message appears at another point on the surface of the liquid. This behavior What is really going on between the two entangled systems created in this experiment is amazing. This amazing phenomenon is somewhat understandable if we think of its holographic equivalent: the message Alice wrote was swallowed up by the wormhole and delivered to the end where Bob is,” adds the author of Quantum revolution.

Casas adds: “What has been achieved is very interesting because it is with a much more powerful computer [en la simulación solo se han utilizado nueve cúbits] Macroscopic systems can be simulated and the effects of quantum gravity on them studied.”

The study was published in nature He admits that the simulation could have been done with traditional computing, but using Google Sycamore adds an essential element. In this sense, the California Institute of Technology highlights that the simulation completed using the Google computer “opens up the possibility of performing quantum gravity experiments on processors based on this physics”, thus multiplying the possibilities of studying this science and this computing.

The same is the opinion of Ignacio Cirac, Director of the Department of Theory at the Max Planck Institute for Quantum Optics in Garching (Germany). Existing quantum computer models or those to be built in the near future may become a key tool for addressing fundamental questions. The experience is still very basic, but it is an important step. This kind of simulation can provide information about how black holes behave, especially when we consider them from the perspective of quantum physics, Cirac explains to the Science Media Center (SMC).

Carlos Sabin, a Ramón y Cajal researcher at the Department of Theoretical Physics at the Autonomous University of Madrid (UAM), considers it also important to understand that no wormhole was created in this experiment. And he qualified: “We are talking about an analogy.” But he stresses that the experiment involves creating “a dictionary that translates into language what happens to a real qubit as to what might happen to a simulated or virtual qubit.” The authors’ Sabin also add to SMC “techniques that show how an experiment can be efficiently extended to a larger number of qubits, so that an experiment can be performed beyond the capabilities of a conventional computer once we have quantum computers with lower error probabilities, which is expected in the coming years.” The physicist concludes: “In any case, this experiment shows that, even with a small number of qubits and existing error probabilities, quantum computers can do really interesting things.”

Adam Brown and Leonard Susskind, researchers at Google and the Department of Theoretical Physics at Stanford University (California) stand out in nature The importance of simulating the hologram principle “as evidence for the combination of quantum mechanics and general relativity”, an aspect that has sought for decades to find a theory that allows us to understand nature. They also highlight the importance of information transmission: “In the non-gravity description, the appearance of the unencrypted message elsewhere is an obvious prediction of quantum mechanics, but it is somewhat vague. The surprise was not that the message arrived somehow, but that it arrived undecoded.” However, this can be easily understood from the description of gravity: the message arrives unencrypted on the other side as it passed through the wormhole.

They concluded that “we may expect, in the future, to invent quantum communication techniques that are difficult to analyze by conventional means, but which use the hologram binary as a powerful analysis and discovery tool.”

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