Wormholes are a hallmark of science-fiction that allow stranded heroes to jump into a black hole and be spit out the other side of the universe without a scratch. While scientific theories from the likes of Einstein do support the possibility of wormholes, in reality they would likely be extremely deadly. That is, if they even exist at all.
Scientists have spent decades pondering over the existence of such wormholes and now a team of scientists from MIT, Caltech, Harvard, and Google, have reported successfully creating a “holographic” wormhole using Google’s Sycamore quantum computer that allows information to travel through it. These findings were published Wednesday in the journal Nature.
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Maria Spiropulu is a senior author on the paper and a professor of physics at Caltech. In a press statement, she said that this work is an important step for scientists in using quantum computers to better understand an aspect of science concerning wormholes called quantum gravity—such a description of gravity using quantum mechanics could help scientists finally unify the quantum and classical worlds of physics. This computational approach offers insights that complement observations from, for example, MIT and CalTech’s Laser Interferometer Gravitational-Wave Observatory (LIGO) project, which seeks to detect and investigate gravitational waves in the universe.
“It does not substitute direct probes of quantum gravity the way LIGO or other experiments are planning using quantum sensing, but it offers a powerful testbed to exercise ideas of string theory and quantum gravity,” Spiropulu said.
So, did scientists open up dangerous, light-eating black holes in a lab to demonstrate this science? Definitely not. According to Spiropulu, this experiment created “no rupture of spacetime.”
To understand this distinction, it’s important to first understand what Spiropulu and colleagues mean when they say “holographic.” In everyday life, the term might bring to mind a cheap light trick that produces virtual, 3D images. For Spiropulu and colleagues, however, the definition of the term in their work is closer to meaning that one system is a “proxy” for another. In particular, the entanglement of several qubits in the Sycamore computer is a stand-in for a real, physical wormhole in space.
Instead of connecting two blackholes with a wormhole bridge, the researchers created an entangled state (a quantum mechanical phenomena where distant particles can still communicate with each other) between two halves of a quantum computer and sent a message in between. This message was scrambled as it entered the system and, through entanglement, unscrambled on the other side.
Based on the success of this quantum model, the team determined that their holographic wormhole had been traversed.
While this science is fascinating, Spiropulu and authors of a commentary essay also published in Nature admit that it’s not necessarily a ground-breaking finding unto itself. In fact, because this experiment only used nine qubits, Spiropulu said that this experiment also could have been done on a classical computer as well.
Instead, the importance of this work is that it’s a proof-of-principle for how quantum computers can be used to help scientists explore complex ideas like quantum gravity. Today’s quantum computers may not be up to the challenge just yet, but Spiropulu said that continued improvements in their development could play a big role in future discoveries.
“Due to the holographic principle, we expect more ‘gravity experiments’ to be performed by quantum computers in the future,” she said. “Some of these require much larger quantum computers or much deeper circuits, but others are well-suited for near-term experimentation.”
