The Thin Edge of Entanglement Wedges and Progress in Quantum Gravity

Although quantum mechanics is a very powerful model of reality, it offers no widely accepted explanation for one of the fundamental forces of the universe: gravity. Fortunately, theoretical physicists have made remarkable progress over the past few years to explain the mysterious microscopic origin of this force.

As part of this effort, many recent studies are pointing towards a surprising equivalence between gravitational theories and quantum systems called holography. Holography predicts that quantum entanglement has a direct correspondence with the geometry of gravitational spacetime.

Similarly, entanglement wedge reconstruction is a conjecture about the duality of a given region in an entangled quantum system and a specific portion, or ‘wedge’, of spacetime. However, this duality is almost always tackled by assuming a mysterious geometry called the anti-de Sitter space.

In a recent study published in the Physical Society of Japan’s Progress of Theoretical and Experimental Physics, physicists from Kyoto University demonstrate how the shapes of entanglement wedges can be derived directly from the other side of the duality, known as conformal field theories, or CFT.

In their method, they employ special metrics, inspired by the quantum information theory, to calculate the distinguishability between different excited quantum states. They show that these states are distinguishable only when they are within a holographic CFT wedge, which in turn corresponds to a ‘shadow’ of the actual entanglement wedge.

This new approach will enable physicists to analyze complex quantum systems in much simpler geometries in gravitational spacetime through entanglement wedges, which in turn could be useful in designing and developing quantum computers.

This study also adds another piece to the puzzle of the quantum origin of gravity, which has been gatekeeping a formulation of the ultimate Laws of Nature.