A group of researchers recently announced that they had simulated a pair of black holes in a quantum computer and sent a message between them through a shortcut in space-time called a wormhole. The physicists described the achievement as another small step in trying to understand the relationship between gravity, which shapes the universe, and quantum mechanics, which governs the subatomic realm of particles.
“This is important because what we have here in its shape and structure is a baby wormhole,” said Maria Spiropulu, leader of the Quantum Communication Channels for Fundamental Physics consortium, which conducted the research. “And we hope to be able to do small wormholes and adult wormholes step by step.”
In their report, published in the journal Nature, the researchers described the result in measured words: “This work is a successful attempt to observe the dynamics of a traversable wormhole in an experimental setting.”
The wormhole that the researchers created and exploited is not a tunnel through actual physical space, but an “emergent” two-dimensional space. The “black holes” were not real, but lines of code in a quantum computer. Strictly speaking, the results apply only to a simplified “toy model” of a universe—particularly one that resembles a hologram.
The results do not offer the prospect of a cosmic subway system through which to roam the galaxy anytime soon, and perhaps never.
Physicists have reacted with interest and caution, expressing concern that people mistakenly think that real wormholes have been created.
“If this experiment has brought a wormhole into actual physical existence, then it could be argued that you, too, bring a wormhole into actual physical existence every time you draw one with pen and paper,” wrote Scott Aaronson, an expert. in quantum computing at the University of Texas at Austin via email.
Quantum computers work with qubits, which can be 0 or 1 or anywhere in between until they are measured or observed. The experiment was carried out on a version of Google’s Sycamore 2 computer, which has 72 qubits. Of these, the team only used nine to limit the amount of interference and noise in the system. Two were reference qubits, performing the input and output functions.
The other seven qubits contained the two copies of the code describing a “sparse” version of an already simple model of a holographic universe called SYK. Both SYK models were packed into the same seven qubits. These SYK systems played the role of two black holes, one encoding a message into nonsense—the quantum equivalent of swallowing it—and then the other ejecting it back.
“To this we add a qubit,” said Joseph Lykken, an author on the paper; he was referring to the input message—a quantum analog of a series of ones and zeros. This qubit interacted with the first copy of the SYK qubit; its meaning was scrambled into random noise and disappeared.
Then, in a tick of the quantum clock, the two SYK systems connected and a shock of negative energy passed from the first system to the second, briefly opening the latter.
The signal then reappeared in its original, unencoded form—at the ninth and final qubit, attached to the second SYK frame, which represented the other end of the wormhole.
One clue that the researchers were recording “wormhole-like” behavior, Lykken said, was that the signals emerged from the other end of the wormhole in the order in which they entered.
In a Nature paper accompanying Jafferis’s study, Leonard Susskind and Adam Brown, physicists at Stanford University in California, noted that the results could shed light on some mysterious aspects of quantum mechanics.
“The surprise is not that the message got through somehow, but rather that it did so unencrypted,” the two authors wrote.
The easiest explanation, they added, is that the message went through a wormhole, albeit a “really short one,” Lykken said. In quantum mechanics, the shortest length conceivable in nature is 10³³ centimeters, the so-called Planck length. Lykken calculated that his wormhole was perhaps only three Planck lengths.
“It’s mini-wormhole crap,” he said. “But that’s really cool because now we’re clearly doing quantum gravity.”
By: DENNIS OVERBYE
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/6491454, IMPORTING DATE: 2022-12-13 06:00:08
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