Scientists Uncover the “Entropy” of Quantum Entanglement

Scientists from RIKEN and the University of Amsterdam have found a rule of “entropy” for quantum entanglement, a key resource in quantum computing. This finding could help us better understand and harness the power of entanglement, which has been a mystery for decades.

The Second Law of Thermodynamics and Quantum Entanglement

The second law of thermodynamics is one of the most important laws of nature. It says that a system can never become more ordered on its own. This law creates the “arrow of time” and explains how even very complex things like gases and black holes behave using a single idea called “entropy.”

But there’s a problem. While the second law works for all classical systems, we’re now exploring the quantum world more and more. Quantum entanglement, which allows for big advantages in communication, computation, and cryptography, is very important but also very complex. Figuring out how to efficiently use and understand entanglement has been a huge challenge.

A Reversible Framework for Entanglement

The difficulty is that a “second law” for quantum entanglement would require showing that entanglement transformations can be reversed, just like work and heat can be converted back and forth in thermodynamics. Previous attempts to establish a reversible theory of entanglement have failed, and some even thought it might be impossible.

But in their new work, published in Nature Communications, Bartosz Regula from RIKEN and Ludovico Lami from the University of Amsterdam solved this long-standing problem. By using “probabilistic” entanglement transformations, which only work some of the time but provide more power, they showed that a reversible framework for entanglement is possible. This identifies a unique “entropy of entanglement” that governs all entanglement transformations.

“Our findings mark significant progress in understanding the basic properties of entanglement, revealing fundamental connections between entanglement and thermodynamics,” said Regula. “This not only has immediate applications in the foundations of quantum theory but will also help with understanding the ultimate limitations on our ability to efficiently manipulate entanglement in practice.”

Looking to the future, Regula noted that their work is the first evidence that reversibility is achievable in entanglement theory, but even stronger forms may be possible without relying on probabilistic transformations. “Understanding the precise requirements for reversibility to hold thus remains a fascinating open problem,” he said.

Keyword/Phrase: Quantum Entanglement Entropy

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