Long-range quantum entanglement requires three-way interaction

A theoretical study shows that long-range entanglement can actually survive temperatures above absolute zero if the correct conditions are met.

Quantum computing has been hailed as the next revolutionary step in computing. However, current systems are only practically stable at temperatures close to absolute zero. A new theorem from a Japanese research collaboration provides insight into the types of long-range quantum entanglements that survive non-zero temperatures, revealing a fundamental aspect of macroscopic quantum phenomena and paving the way for better understanding of quantum systems and for the design of new spaces. temperature stable quantum devices.

When things get small, down to a thousandth of the width of a human hair, the laws of classical physics are replaced by those of quantum physics. The quantum world is strange and wonderful, and there is much about it that scientists have not yet figured out. Large-scale or “macroscopic” quantum effects play a key role in extraordinary phenomena such as superconductivity, which can be a game-changer in future energy transport, as well as for the continued development of quantum computers.

It is possible to observe and measure “quantity” on this scale in certain systems using long-range quantum entanglement. Quantum entanglement, which Albert Einstein described as “frightening action at a distance”, occurs when a group of particles cannot be described independently of each other. This means that their properties are related: if you can completely describe a particle, you will also know everything about the particles it is wrapped with.

Long-range entanglement is at the heart of quantum information theory, and its better understanding could lead to a breakthrough in quantum computer technologies. However, long-range quantum entanglement is stable under specific conditions, such as between three or more parties and at temperatures close to absolute zero (-273 ° C). What happens to two-part entangled systems at non-zero temperatures? To answer this question, researchers from the RIKEN Center for Advanced Intelligence Project, Tokyo, and Keio University, Yokohama, recently presented a theoretical study on Physical examination X describes long-range entanglement at temperatures above absolute zero in two-part systems.

“The aim of our study was to identify a limitation of the structure of long-range entanglement at arbitrary non-zero temperatures,” explains Tomotaka Kuwahara, head of the RIKEN Hakubi team, one of the study’s authors who conducted the study. research while at the RIKEN Center for Advanced Intelligence Project. “We provide simple prohibition theorems that show the types of long-range intricacies that can survive non-zero temperatures. At temperatures above absolute zero, particles of a material vibrate and move due to thermal energy, which counteracts quantum entanglement. At arbitrary temperatures , which is not zero, there can be no long range entanglement between just two subsystems. “

The researchers’ results are consistent with previous observations that long-range entanglement only survives at non-zero temperature when more than three subsystems are involved. The results suggest that this is a fundamental aspect of macroscopic quantum phenomena at room temperature and that quantum devices should be designed to have multipartite entangled states.

“This result has opened the door to a better understanding of quantum entanglement over long distances, so this is just the beginning,” said Professor Keijo Saito of Keio University, co-author of the study. “We aim to deepen our understanding of the relationship between quantum entanglement and temperature in the future. This knowledge will trigger and stimulate the development of future quantum units that operate at room temperature, making them practical.”

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Materials supplied by RIKEN. Note: The content can be edited for style and length.

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