# Google scientists use quantum computers to study worm holes

BEIJING, Dec. 4 (Xinhua) — Researchers at Google are studying how to explore in the lab some of the strange physical phenomena that exist only in theory, such as wormholes connecting two black holes. Today, a central issue driving the development of theoretical physics is how to use the same theory to explain the rules followed by microscopic particles such as atoms and so on.

A concept schematic of information falling into a black hole

Since gravity is an extremely weak force, it is virtually impossible to detect it on the smallest scale using today’s technology. But theoretical work has suggested that “quantum gravity” may appear in specific quantum systems, or even one day be made in the lab. Google physicists have proposed an experiment that assumes that a quantum state that can be recreated in a physical laboratory could be interpreted as information that travels through a hole between two black holes.

“Thus, experimental studies of this condition provide a way to better understand quantum gravity,” the study authors wrote in a paper published on the preprinted website arXiv. “

Gravity seems to be unable to reconcile with quantum mechanics, and theoretical physicists have been trying to string the two concepts together. But in some places, at some point, these two concepts must exist at the same time, such as on the surface of a black hole or inside a black hole, and at the moment of the Big Bang. String theory is one of the most popular theories that link the two, and it replaces subatomic particles with tiny strings that vibrate in high-dimensional space. String theory exists on a scale far smaller than the particle accelerator detection range, so it is difficult to detect. However, more than 20 years ago, scientists came up with the idea of a “AdS/CFT pair”, which essentially suggests that you can interpret the high-dimensional gravity in this high-dimensional world as a hologram produced by quantum mechanical particles. As a result, a team of physicists at Google, the California Institute of Technology, the University of Maryland and the University of Amsterdam believe that studying extreme quantum behavior may provide more powerful evidence of string theory. Perhaps quantum computers can create behaviorthatthat that detects string theory, or phenomena like wormholes.

One of the most important advances in physics in the last decade has been the development of machines that control and manipulate quantum states, which we call quantum computers and quantum simulators. The smallest objects, such as electrons moving around atoms, can only have specific property values, but when you don’t look at them, they can have different property values at the same time (when you measure them again, they go back to the state of having only one property value). Two or more particles may also be entangled, meaning that they and their properties must be described as a single mathematical object, even if you separate atoms in space.

Google researchers are proposing to create a loop using two sets of connected qubits (the artificial “atoms” of quantum computers) and divide them into groups left and right. The pulse of the input energy is mathematically equivalent to allowing the state of the qubit to evolve backward over time, while another pulse encodes “information” by changing the quantum state of the left-hand atom in a specific way. Thus, this other pulse acts to accelerate quantum bit behavior. This setting is crucial to the analogy of black holes, because mathematically, the disruption of information between quantum bits is similar to that of particles when they enter the black hole, and may be lost. Once the information is disrupted, each qubit on the left is entangled with the mirrored qubit on the right. Finally, after a period of time, the information mysteriously reappears in the qubit on the right without any decoding.

“The way this information is transmitted to the other side of the system is not obvious at all, and the most surprising fact is that the simplest explanation lies in the physics of black holes,” the study authors wrote in the paper. “In essence, the researchers believe, the transmission of information between groups of quantum bits in a system is similar to a piece of information entering a black hole, passing through a wormhole, and then emerging from a second black hole. The researchers then introduced a mathematical framework to illustrate the entire process and how it was compared to a wormhole that would not collapse.

According to the paper’s description, physicists are likely to implement this system in the laboratory. One possible device consists of an array of atoms, which are either in the lowest energy state or in a highly energetic “Rydberg state” state, controlled by a laser pulse. The other device consists of a captured array of charged ions. Maybe one day, one of these devices will be able to do the experiment proposed by Google.

Simply put, scientists think they can mathematically simulate the transmission of information through wormholes between two black holes through quantum computers. Obviously, it’s impossible to produce worm holes on Earth, so it’s just a model, like any other simulation system, just because the mathematical description of the experiment looks like a theory that describes space. Of course, this does not mean that the theory must be correct. These models are just to present stronger mathematical evidence that a theory may be correct.

This work is based on the disruption of quantum information over time, and the connection between this disruption and black holes. Still, it excites physicists. Not long ago, dozens of physicists discussed at the Google X conference how quantum technology could be used by quantum gravity researchers. “It was really exciting to hear about this experiment,” says Guillaume Verdon. “

Christopher Monroe, a physics professor at the University of Maryland who was involved in the study, said the quantum computer described in the paper is coming soon and could create a hot-field dual-state qubit that simulates a wormhole. His own team is working on quantum computers that capture ions, and he hopes to make it a platform soon to create the quantum states needed to test these ideas. “Papers like this inspire us and drive us to build these models in universities, companies, and government laboratories,” he said. “