Overview

The Holy Grail of modern physics is the unification of the two theories that explain the Universe: quantum mechanics and Relativity. The former describes the behavior of nature in the subatomic regime, and the latter offers a solid model to understand gravitational phenomena. These two approaches to physical reality have been beneficial for solving problems and predicting things in their corresponding regimes for more than a century. But when physicists want to use both techniques on a phenomenon, the mathematics breaks down. Moreover, both models seem to be irreconcilable. Now, a new study in quantum gravity is revolutionizing physicists worldwide after finding empirical evidence of a remote connection between quantum and Relativity.

The science and other stuff to know

A study published on November 30 in Nature recounts the feat achieved by a collaboration between Caltech, MIT, Google, Harvard, and Fermilab. They managed to reproduce a wormhole in a quantum processor and specify the journey of a q-bit. This development is astonishing, revolutionary, and certainly unexpected for the scientific community that throws up its hands to see new physics on the horizon.

In 1935 Albert Einstein and Nathan Rosen proposed the existence of “gravitational bridges:” a space-time tunnel connecting two black holes. These are currently known as wormholes or ER bridges. The same year these authors, together with Boris Podolski, proposed an effect known as quantum entanglement, which consists of a “spooky action at a distance,” as Einstein called it, between two particles. In an entangled system, both particles store information about the other, and if one changes its state, the other responds immediately, no matter how far apart they are. This phenomenon is known as the EPR paradox.

Until 2013, the only thing these proposals had in common was their authors. It was then when Juan Maldacena and Leonard Susskind established the ER=EPR duality, which suggested that these two phenomena of opposite natures — ER is a gravitational phenomenon and EPR is a quantum one — are not irreconcilable but somewhat equivalent.

In 2019, the team of collaborators revolutionizing the field began to design an experiment to test the duality proposed by Maldacena and colleagues. Using the foundations of the holographic theory proposed in 1999 by Maldacena and neural networks, the experimental physicists made the Sycamore quantum processor reproduce the mathematics of a gravitational wormhole.

In January 2022, they finally found conclusive evidence in the Sycamore data that the thing they longed for had happened: they had created a quantum wormhole in a computer.

Although the details of the phenomenon are highly technical, we can simplify it by using an analogy: Inside the processor, a q-bit — the basic unit of quantum information — “disappeared” from one location and “appeared” in another, just as it would be expected to do in the presence of a wormhole.

So what?

This discovery is relevant because it is the first experimental evidence of the ER=EPR duality, the first evidence of a connection between Relativity and quantum mechanics. Although, until now, there is a fine thread that unites them, we know in which direction to dig to find more connections and eventually a formulation that unifies them.

What’s next?

Implementing quantum processing technologies in experiments of this type is the most effective tool to explore mysterious quantum regimes. Thus it is to be expected that by improving hardware and machine learning models, physicists will design more ambitious and sophisticated experiments that can provide us with empirical evidence for the wildest physical theories.